Sustainable colloidal nanostructures for advanced PEMFC coolants: stability, environmental implications, and lifecycle challenges

1 Introduction

Proton Exchange Membrane Fuel Cells (PEMFCs) are increasingly recognized as a pivotal technology in the transition toward sustainable and low-carbon energy systems. Their ability to deliver high power density, operate at relatively low temperatures, and produce minimal environmental emissions makes them suitable for a wide range of applications, including automotive propulsion, portable power generation, and backup energy systems (Chandra Kishore et al., 2023; Zhang Z. et al., 2024; Li et al., 2021) With global interest growing in decarbonizing the transportation and energy sectors, PEMFCs are being actively integrated into commercial and industrial platforms. However, to ensure their widespread adoption and long-term viability, challenges related to performance optimization and durability must be effectively addressed. Among the critical technical limitations hindering the widespread implementation of PEMFCs is thermal management, particularly in stack configurations exceeding 1 kW output. In practical operations, heat generated from electrochemical reactions can accumulate rapidly within the stack, resulting in localized overheating. This thermal imbalance can cause severe performance degradation, non-uniform current density distribution, and irreversible damage to membrane electrode assemblies (Ansari et al., 2021; Zhang and Kandlikar, 2012).

Existing cooling strategies are often insufficient to handle the dynamic thermal loads experienced during transient operating conditions, especially in high-power systems, leading to reduced stack efficiency and service life (Su et al., 2025). One of the key problems in current PEMFC stack design is the inadequate regulation of internal temperatures during prolonged or fluctuating load conditions. Insufficient cooling mechanisms can lead to elevated cell temperatures that exceed the operational limits of the proton exchange membrane, causing drying, delamination, or chemical degradation. These thermal stresses not only impair proton conductivity but also compromise the mechanical stability of other components, such as the gas diffusion layers and bipolar plates (Mitincik and Yazici, 2026). Despite improvements in flow-field design and material selection, effective and consistent coolant management remains an unresolved engineering challenge. The second major issue concerns the correlation between inefficient coolant distribution and accelerated component degradation. Uneven thermal distribution across the stack heightens the risk of hot spots, which in turn worsens catalyst layer deterioration, water management issues, and membrane thinning over time. This degradation directly influences the stack’s electrochemical efficiency and long-term durability, making it less suitable for commercial applications requiring high reliability and extended operational lifetimes (Sofiah et al., 2024a; Wang et al., 2026). Therefore, understanding how the coolant strategy affects individual component longevity is crucial for improving the robustness of PEMFC systems.

Recent advances in PEMFC thermal management have shifted attention from conventional coolant fluids towards advanced coolant systems capable of improving heat transfer while maintaining long-term operational stability. In particular, nanostructured colloidal coolants have emerged as promising alternatives because their thermophysical properties can be tailored through particle composition, concentration, and surface engineering. However, thermal conductivity enhancement alone is insufficient to justify their practical implementation. Colloidal stability, viscosity, electrical conductivity, corrosion behaviour, compatibility with stack materials, and environmental sustainability must also be considered when evaluating advanced coolant formulations. Consequently, there is a growing need to examine coolant development from both engineering and sustainability perspectives rather than solely from the viewpoint of overheating mitigation (Elsaid et al., 2021; Islam et al., 2015).

Figure 1 illustrates the general arrangement of cooling plates within a PEMFC stack, highlighting the central role of coolant circulation in maintaining temperature uniformity and preventing local overheating. Against this engineering background, the present review critically evaluates recent developments in coolant management for PEMFC systems, with particular emphasis on advanced colloidal nanostructures, nanofluid formulations, coolant stability, and their influence on stack performance, durability, and environmental sustainability. Conventional cooling strategies are first reviewed to establish the thermal requirements of PEMFC stacks, followed by a critical assessment of emerging nanostructured coolants, cooling architectures, and unresolved challenges associated with long-term stability, material compatibility, and lifecycle considerations. The review further identifies current research gaps and future directions for developing sustainable coolant technologies for next-generation PEMFC systems. Within the scope of this review, sustainability extends beyond improvements in thermal performance and encompasses environmentally responsible material selection, green synthesis approaches where applicable, long-term colloidal stability, resource efficiency, compatibility with PEMFC components, and responsible end-of-life management. Accordingly, advanced colloidal nanostructures are evaluated using an integrated framework that considers thermal, hydraulic, electrochemical, and environmental performance to support the development of practical and sustainable PEMFC cooling technologies. Unlike previous reviews that primarily focus on individual cooling technologies or general thermal management strategies, this review provides an integrated and sustainability-oriented assessment of advanced PEMFC coolants by jointly evaluating colloidal nanostructure design, thermophysical performance, dispersion stability, material compatibility, environmental implications, and lifecycle considerations within a unified framework.

2 Thermal and operational requirements for advanced PEMFC coolants

2.1 Heat generation in PEMFCs

Proton exchange membrane fuel cells (PEMFCs) inherently generate substantial heat during operation, making thermal management a critical determinant of stack design, performance stability, and long-term durability. Figure 2a, reproduced from Nguyen and Shabani (Nguyen and Shabani, 2020), illustrates the energy flow within a PEMFC based on the experimental investigation reported by (Shabani and Andrews, 2011). In practical operation, only approximately 40%–60% of the chemical energy released during hydrogen oxidation is converted into useful electrical energy, while the remaining fraction is irreversibly dissipated as heat. This unavoidable heat generation arises from multiple interrelated mechanisms, including electrochemical reactions, resistive losses, and mass transport limitations within the cell (Soubeyran et al., 2024). A major contribution to heat generation arises from the exothermic hydrogen–oxygen electrochemical reaction. Although a portion of the reaction enthalpy is transformed into electrical work, the difference between the reversible thermodynamic voltage and the actual operating voltage is released as thermal energy. The magnitude of this reaction-related heat strongly depends on operating current density, cell voltage, and load dynamics, and becomes increasingly pronounced under high-power or transient operating conditions (Xie et al., 2024). In addition to reaction heat, irreversible electrochemical losses significantly contribute to internal heat generation. Ohmic heating results from resistance to proton transport within the polymer electrolyte membrane, electronic resistance in the catalyst layers and gas diffusion layers, and interfacial contact resistance at the electrode-bipolar plate interfaces. These losses increase linearly with current density and represent a dominant heat source during high-load operation. Moreover, activation losses at the anode and cathode catalyst sites, arising from kinetic barriers to electrochemical reactions, also dissipate energy as heat, particularly at lower operating temperatures or under suboptimal reactant availability (Chen Q. et al., 2021; Spiegel, 2011). Mass transport limitations further intensify heat generation, especially at elevated current densities. Insufficient reactant supply, accumulation of product water, and gas diffusion constraints lead to concentration overpotentials, which reduce the effective cell voltage and convert additional chemical energy into heat. These losses are highly sensitive to flow-field architecture, local humidity distribution, and operating pressure, resulting in spatially non-uniform heat generation across the active area. Consequently, heat production within PEMFCs is intrinsically heterogeneous, often giving rise to localized hot spots in regions experiencing high current density, restricted mass transport, or inadequate cooling. Such thermal non-uniformities accelerate membrane dehydration, catalyst degradation, and mechanical stress. In multi-cell stack configurations, disparities in heat removal efficiency among individual cells further amplify temperature gradients across the stack, posing significant challenges for maintaining thermal uniformity and operational stability (Sarjuni et al., 2024). It is widely reported that approximately 90% of the total heat generated within a PEMFC stack must be removed by the cooling system to maintain safe and efficient operation (Zhang et al., 2018). As the stack temperature increases, low-temperature coolant is actively circulated through cooling channels embedded within the bipolar plates. The coolant absorbs the internally generated heat, resulting in a significant temperature rise between the inlet and outlet streams. The heated coolant subsequently flows through a radiator, where forced convection, assisted by a cooling fan, facilitates heat exchange with the surrounding air. After cooling, the fluid is recirculated back into the PEMFC stack, thereby completing the thermal management loop (Song et al., 2025).

The overall heat dissipation process from the PEMFC stack to the ambient environment can be divided into four distinct heat transfer pathways, as illustrated in Figure 2b (Huang et al., 2022). The lower schematic in Figure 2b represents the computational domain and boundary conditions commonly adopted for numerical thermal analysis of PEMFC stacks. The applied heat flux at the lower surface represents the thermal energy generated during the electrochemical reactions within the membrane electrode assembly. The cooling inlet and cooling outlet indicate the coolant flow path through the cooling channels, where heat is absorbed and transported away from the stack. A symmetry boundary condition is applied to reduce computational cost while preserving the thermal and flow characteristics of the complete geometry. These boundary conditions provide the basis for predicting temperature distribution, coolant performance, and heat dissipation within PEMFC cooling systems. The computational domain illustrated in the lower half of Figure 2b further provides a simplified CFD framework for analysing coolant flow behaviour, local heat removal, and temperature uniformity. Such numerical models support the optimisation of cooling-channel design and coolant selection before experimental validation.

In this schematic, red regions represent high-temperature zones, while blue regions indicate cooler areas. Heat conduction dominates internal heat transfer within PEMFCs, making the thermal conductivity of individual components a key parameter governing temperature distribution, thermal gradients, and overall thermal management effectiveness.

2.2 Impact of overheating on stack components

Uncontrolled overheating adversely affects nearly all functional components of proton exchange membrane fuel cell (PEMFC) stacks, with the severity of degradation depending on the thermal sensitivity and material properties of each layer (Huang et al., 2022). Sustained temperature excursions beyond the optimal operating range accelerate both performance losses and irreversible degradation processes, ultimately compromising stack durability and reliability. The polymer electrolyte membrane, typically composed of perfluorosulfonic acid (PFSA) materials such as Nafion, is particularly vulnerable to elevated temperatures. At temperatures exceedingly approximately 80 °C, membrane dehydration becomes pronounced, leading to the collapse of ionic conduction channels and a sharp decline in proton conductivity. This dehydration-induced conductivity loss significantly increases ohmic resistance, resulting in reduced cell voltage and overall performance deterioration (Fernández-Sotillo and Ferreira-Aparicio, 2023). Repeated thermal cycling between hydrated and dehydrated states further induces mechanical stress within the membrane, promoting the formation of microcracks, pinholes, and gas crossover pathways that accelerate chemical degradation and membrane failure. Overheating also severely impacts the catalyst layers. Prolonged exposure to elevated temperatures enhances platinum (Pt) dissolution, migration, and agglomeration, causing a substantial reduction in electrochemically active surface area (ECSA) and a corresponding decline in catalytic activity (Qasem, 2024). In parallel, high thermal stress accelerates carbon support corrosion, weakening catalyst anchoring and exacerbating irreversible performance losses. These effects are particularly pronounced at the cathode, where high potentials and temperature gradients coexist.

The gas diffusion layer (GDL), which plays a critical role in reactant transport and water management, is likewise susceptible to thermal degradation. Excessive temperatures alter the surface wettability and microstructure of the GDL, often reducing its hydrophobicity. This degradation disrupts the delicate balance between water retention and removal, leading to either flooding due to liquid water accumulation or local dry-out caused by excessive evaporation. Both scenarios impede gas diffusion pathways, increase mass transport resistance, and contribute to localized performance losses (Yang et al., 2024; Asanin, 2020). Bipolar plates, commonly fabricated from graphite-based or metallic materials, are also affected by overheating and temperature non-uniformity. Elevated temperatures and steep thermal gradients induce non-uniform thermal expansion, generating mechanical stresses that can cause plate warping, increased interfacial contact resistance, and micro-leakages at sealing interfaces. In metallic bipolar plates, high temperatures further accelerate corrosion processes, leading to surface oxide formation and a progressive increase in electrical resistance, which degrades stack efficiency and operational stability (Qasem, 2024). Collectively, these thermally induced failure mechanisms underscore the critical importance of robust thermal and coolant management in PEMFC stacks. Excessive thermal loads not only impose immediate performance limitations but also accelerate long-term degradation pathways that shorten stack lifetime and increase system-level operational costs (Tang et al., 2021). Therefore, effective overheating mitigation is crucial for achieving durable, high-performance operation of PEMFC stacks.

2.3 Critical temperature ranges for PEMFC operation

Maintaining proton exchange membrane fuel cell (PEMFC) stacks within a well-defined and narrow temperature window is essential for achieving an optimal balance between electrochemical performance, component durability, and operational safety. For conventional low-temperature PEMFCs employing perfluorosulfonic acid (PFSA) membranes such as Nafion, the optimal operating temperature typically lies in the range of 60 °C–80 °C. Within this window, proton conductivity, membrane hydration, and reaction kinetics are simultaneously optimized, resulting in stable voltage output and efficient water management (Zakaria et al., 2020). Operation beyond this optimal range leads to distinct and often irreversible degradation mechanisms. At elevated temperatures above approximately 80 °C, accelerated membrane dehydration occurs, causing a pronounced reduction in proton mobility and a sharp increase in ohmic losses. Prolonged exposure to temperatures exceeding 100 °C can further induce chemical degradation of the polymer backbone, compromising membrane integrity and accelerating gas crossover and failure processes (Chen et al., 2021c). These effects are particularly critical under high-current or transient operating conditions, where localized temperature spikes are more likely to occur.

Conversely, operation at lower temperatures, typically below 50 °C, adversely affects water management within the cell. Reduced evaporation rates promote excessive water condensation in the catalyst layers and gas diffusion layers (GDLs), leading to flooding of porous structures. This flooding obstructs reactant gas transport, particularly oxygen supply at the cathode, resulting in significant concentration overpotentials and voltage losses. Low-temperature operation also slows electrochemical reaction kinetics, further degrading performance efficiency. Beyond absolute temperature limits, spatial and temporal temperature variations within the stack significantly impact PEMFC durability. Thermal gradients and localized hotspot formation arise from non-uniform current density distribution, uneven reactant supply, and insufficient cooling efficiency. These non-uniformities intensify mechanical stress, disrupt electrochemical kinetics, and accelerate localized material fatigue and degradation. In multi-cell stacks, cell-to-cell temperature disparities propagate stack-level non-uniformity, further complicating thermal control (Desai et al., 2024). The interaction between temperature and humidity adds another layer of complexity. Even within the nominally safe operating range of 60 °C–80 °C, under-humidification can induce membrane dehydration effects similar to those observed at elevated temperatures, while over-humidification exacerbates flooding phenomena typically associated with low-temperature operation. This strong coupling highlights the need for integrated thermal and water management strategies, rather than isolated temperature control.

The challenge of maintaining critical temperature limits becomes more pronounced in practical applications such as automotive and portable PEMFC systems, which are frequently subjected to rapid load fluctuations and dynamic operating conditions. Such transient loads can trigger sudden thermal excursions, leading to localized overheating, membrane thinning, and irreversible component damage if not properly managed (Bargal et al., 2021; Bargal et al., 2020). Therefore, strict control of operating temperature, thermal gradients, and transient thermal behavior is indispensable for ensuring high efficiency, long service life, and reliable performance of PEMFC stacks under realistic operating conditions.

3 Evolution from conventional cooling to advanced coolant systems

Thermal management within PEMFC stacks remains a critical challenge, as uneven temperature distributions can lead to reduced performance, material degradation, and diminished longevity. Recent advancements in thermal management techniques have been developed to address these issues, focusing on enhancing thermal uniformity, optimizing heat dissipation, and improving overall efficiency. Elevated or poorly regulated operating temperatures have been strongly associated with key degradation pathways in PEMFCs. For instance, higher coolant temperatures accelerate membrane thinning, increase ionic resistance, and contribute to catalyst sintering and carbon support corrosion, ultimately reducing ECSA and leading to voltage decay. Studies by Niu et al. (2024) have demonstrated that inadequate heat dissipation in conventional low-temperature PEMFC systems can increase local operating temperatures, intensifying thermal gradients, membrane stress, and catalyst degradation. Complementary findings reported by Leader et al. (2022), although obtained using high-temperature PBI-based PEMFCs operating under different thermal conditions, similarly highlight the importance of effective thermal management for fuel cell durability. These findings are cited as supporting evidence for general thermal degradation mechanisms rather than being directly representative of Nafion-based low-temperature PEMFC operation.

A wide range of coolant strategies has been evaluated to mitigate these issues. Air cooling remains attractive due to its simplicity and low cost, yet its effectiveness is limited to low-power stacks (typically <5 kW) due to its low heat capacity and dependence on ambient conditions. Liquid cooling systems, especially those employing nanofluids or dielectric coolants, provide superior thermal control and are more scalable, making them suitable for automotive-scale or stationary systems. For example, Soleymani et al. (2023) reported more than a 20% enhancement in heat transfer using CuO/Al₂O₃ nanofluids in a battery thermal management system compared with conventional water-glycol coolants. Although this study was conducted for battery cooling rather than PEMFC applications, it provides useful adjacent-field evidence demonstrating the potential of nanofluids to enhance heat transfer and reduce thermal resistance, rather than direct quantitative evidence for PEMFC cooling systems. Heat spreaders, including vapor chambers and embedded heat pipes, have also been used to passively distribute heat more uniformly across the stack. Though less effective in high-power applications, these systems are well-suited for compact designs and contribute to hot-spot suppression without additional power draw (Han et al., 2023). On the other hand, integrated heat exchanger systems, such as those coupled with hybrid organic Rankine cycles, allow for advanced thermal recovery but introduce complexity, higher system cost, and increased design constraints (Sarani et al., 2022). Despite these innovations, several gaps persist in the current body of research. Notably, most experimental studies focus on short-term performance gains, with limited data on long-term degradation behavior under varying coolant conditions. There is also a lack of standardized test protocols for comparing coolant strategies across different stack configurations and power outputs. Moreover, scaling challenges remain unresolved, particularly the difficulty of maintaining thermal uniformity across larger active areas without increasing system complexity or parasitic power consumption. Few studies address the coupling between thermal management and dynamic operating conditions such as load cycling, freeze-thaw durability, or altitude variation in UAV applications. Figure 3 illustrates the cooling system in the application stack cooler design and fuel cell electric vehicle.

PEMFC stacks, these insights suggest several practical considerations. First, active coolant temperature regulation, through controlled liquid loops or hybrid cooling systems, should be prioritized to reduce membrane and catalyst degradation. Second, channel geometry and flow field design must be optimized to promote even heat and coolant distribution, particularly in endplate-adjacent regions where edge cooling tends to dominate. Third, material selection plays a crucial role: thermally conductive bipolar plate materials, corrosion-resistant coatings, and advanced MEAs with reinforced membranes are essential for minimizing thermal stress. Finally, lightweight, modular heat spreaders may be employed to balance passive and active cooling, particularly in portable or space-constrained applications. Together, these advancements and design considerations point toward a more integrated, system-level approach to PEMFC thermal management, balancing efficiency, durability, and manufacturability for both low- and mid-power applications. The recent advancements of thermal management techniques in PEMFC stacks are tabulated in Table 1, while the impacts of the cooling techniques on degradation are presented in Table 2. Although a great deal of work has been done on cooling methods for PEMFC stacks, there are still some significant obstacles faced. Most literature studies mainly aimed at short-term thermal performance improvement but rarely covered long-term durability under dynamic operational conditions. In addition, there are still insufficient comparative studies that evaluate hybrid cooling strategies or intelligent thermal management systems. Research moving forward should focus on integrated cooling architectures that couple novel coolants, channel geometry designs, and adaptable control approaches to improve performance and lifetime stability. Figure 4 below shows the conceptual framework of integrated thermal management strategies in PEMFC for this study.

TABLE 1. Recent advanced thermal management methods.

TABLE 2. The key advances in coolant technologies and their implications for the performance and degradation of PEMFC systems.

4 Coolant technologies and the emergence of colloidal nanostructures

Effective cooling plays a critical role in maintaining thermal stability during proton exchange membrane fuel cell (PEMFC) operation. Among the various thermal management approaches, cooling techniques have emerged as one of the most important and actively researched strategies due to their direct influence on stack performance, efficiency, and durability. These techniques exploit physical and thermodynamic principles to regulate heat generation and dissipation within the stack. Cooling management in PEMFCs has evolved significantly over time, with increasing emphasis on optimizing thermal performance to support higher power densities and longer operational lifetimes. Numerous studies have investigated stack-level thermal management using a variety of cooling strategies tailored to different operating conditions and system requirements. Commonly explored approaches include air cooling, liquid cooling, phase change material (PCM)-based cooling, as well as advanced heat transfer devices such as heat spreaders, heat pipes, radiators, and heat exchangers (Lee et al., 2020). Continuous advancements in materials, system integration, and cooling design have further enhanced the effectiveness of these strategies, transforming them into promising solutions for managing heat at the PEMFC stack level. Computational fluid dynamics has also been extensively employed to optimise compact heat exchanger configurations for enhanced thermal performance and coolant flow distribution, providing useful design methodologies applicable to PEMFC thermal management (Agarwal et al., 2021a). The following sections discuss these cooling techniques in detail and evaluate their role in improving stack thermal uniformity and overall performance.

4.1 Conventional coolants and transition towards nanostructured fluids

Cooling techniques at the stack level have undergone substantial development as proton exchange membrane fuel cell (PEMFC) systems continue to operate at higher power densities and under more demanding conditions. Early PEMFC stacks primarily relied on air cooling due to its structural simplicity, low cost, and ease of implementation. However, air cooling exhibits limited heat removal capability and poor temperature uniformity, particularly under high current densities, which restricts its applicability to low-power and portable systems (Romeo et al., 2012). These limitations motivated the transition toward more efficient cooling solutions. Liquid cooling subsequently emerged as the dominant thermal management strategy for medium- and high-power PEMFC stacks (Soupremanien et al., 2012). By employing coolants such as water or glycol-based mixtures, liquid cooling systems offer significantly higher heat transfer coefficients and improved temperature control compared to air cooling (Hamdan et al., 2021). Despite these advantages, early liquid cooling designs often suffered from non-uniform coolant distribution, leading to localized overheating and uneven stack degradation. To address these challenges, advanced concepts such as microchannel cooling, heat pipes, and enhanced cooling plate designs were introduced to improve heat removal efficiency and temperature uniformity (Sasiwimonrit and Chang, 2021). In parallel, the integration of thermoelectric generators (TEGs) with cooling plates enabled partial waste heat recovery, contributing to improved overall system efficiency (Lan et al., 2023). Recently, model predictive control (MPC) has been applied to liquid cooling systems, allowing dynamic adjustment of coolant flow and temperature to achieve precise thermal regulation under transient operating conditions (Wang et al., 2023).

There are common coolants that have been used at the stack level regardless of small or big power capacity, it has significant impacts on overall performance. The choice of coolant significantly impacts PEMFC stack performance and longevity. Water, due to its high specific heat capacity and availability, remains a popular choice, although its low thermal conductivity can limit heat transfer efficiency (Zhang et al., 2023). Glycol-based coolants, particularly ethylene glycol–water and propylene glycol–water mixtures, are commonly employed to enhance freezing resistance and thermal stability across a wide operating range (Raguman and Vedagiri, 2024; Bargal et al., 2024; Choi YW. et al., 2024; Sonia et al., 2024; B et al., 2023). However, these solutions exhibit higher viscosity and may introduce corrosion-related concerns, necessitating careful material selection and system design (Idris et al., 2024). To overcome the thermal limitations of conventional coolants, nanofluids have gained considerable attention in recent years. Nanofluids consist of nanoscale particles, such as Al₂O₃, CuO, TiO₂, SiO₂, ZnO, MgO, or their hybrid combinations dispersed in base fluids like water or ethylene glycol (Bhattad et al., 2023; Ind et al., 2025; Gao et al., 2020; Hosseini and Mirzaei, 2020; Sidik et al., 2016). The inclusion of nanoparticles significantly enhances thermal conductivity, resulting in improved convective heat transfer and reduced temperature gradients within the stack (Maniganda Boopathy et al., 2025; Faisal and Mohammed, 2023; Habib et al., 2024; Wani and Ravi, 2017; Khare and Tyagi, 2025; Kumar and Shaik, 2023; Pandey et al., 2024; Pashikanti et al., 2025; Pattnaik et al., 2023; Periannan et al., 2025; Rudrappa et al., 2025; Sun L. et al., 2024; Thorat et al., 2024; Zakaria, 2024). Similar enhancements in convective heat transfer using nanofluids have also been demonstrated in internally enhanced tube flows, where the combined use of helical inserts and nanofluids substantially improved heat transfer performance while maintaining acceptable hydraulic characteristics (Agarwal et al., 2021b). Research has explored various nanoparticle types, concentrations, and base fluids to optimize nanofluid properties for specific PEMFC applications (Yasmin et al., 2023; Johari et al., 2022; Sofiah et al., 2024b; Souby et al., 2025; Zakaria, 2016; Zakaria et al., 2016).

For example, studies have shown that Al₂O₃-water nanofluids can significantly improve heat transfer rates in IC engines, while CuO nanofluids enhance radiator performance (Khare and Tyagi, 2025). The use of hybrid nanofluids, combining different nanoparticles, has also shown promising results in enhancing thermal conductivity and reducing viscosity (Sun L. et al., 2024; Yu et al., 2023). However, challenges remain in ensuring nanofluid stability and addressing potential issues related to nanoparticle aggregation and long-term effects on system components. Furthermore, the selection of the optimal nanofluid depends on factors such as the specific application, operating conditions, and desired performance characteristics (Sahoo et al., 2023). Recent research also focuses on developing generalized correlations for predicting nanofluid properties, such as density and specific heat, to facilitate better design and optimization of cooling systems (Pattnaik et al., 2023). The use of bio-sourced nanofluids, such as those based on Cocos nucifera shell, offers an environmentally friendly alternative with improved heat transfer properties (Raguman and Vedagiri, 2024). Finally, research is continuing to explore the use of novel coolants, including those based on palm oil and other sustainable materials, to further enhance cooling efficiency and reduce environmental impact (Zhao et al., 2020a). The aforementioned cooling methods discussed are tabulated in Table 3, equipped with their important criteria for stack-level PEMFC, including their future potential.

TABLE 3. Various cooling methods for stack-level PEMFC and its important criteria.

Future potential for stack-level PEMFC applications.

A multizone cooling approach has been proposed to improve temperature control in PEMFC stacks by dividing the cooling region into independently managed zones. This arrangement offers better control of the temperature distribution than conventional single-zone cooling. In the study considered here, the multizone configuration improved cell-voltage and current-density uniformity and produced a performance increase of up to 15.98% at higher current densities (Li and Sundén, 2018). The results were obtained under the stack configuration and operating conditions examined in that study and should therefore be interpreted within that experimental scale rather than as a general performance gain for commercial PEMFC stacks. Nevertheless, the findings demonstrate the potential of zonal cooling to reduce temperature gradients and limit localized overheating (Li and Sundén, 2018).

Thermal management also needs to account for the close interaction between heat removal and water management. Previous work has reviewed waste-heat generation, cooling methods, and cold-start behaviour in PEMFC systems (Chen Q. et al., 2021). Excessive cooling may promote water accumulation, whereas insufficient heat removal can contribute to membrane dehydration and large temperature gradients. Cooling strategies therefore need to consider temperature and water balance together, particularly when operating conditions vary with load. Coolant composition and cooling-channel geometry are also important in this respect. A numerical study examining propylene-glycol-based cooling reported favourable thermal performance for a 20% propylene glycol mixture under the conditions investigated (Sahoo et al., 2023). The same work showed that channel design and coolant distribution affect heat removal and pressure drop. These results are specific to the model and operating conditions considered and should not be interpreted as establishing 20% propylene glycol as universally optimal for PEMFC cooling (Sahoo et al., 2023).

Temperature non-uniformity can also occur along the stack, particularly near the endplates. Endplate heating has been investigated as a means of reducing this so-called “Bucket Effect.” The approach improves the temperature distribution at the ends of the stack and can consequently reduce differences in cell performance associated with non-uniform thermal conditions (Yu et al., 2023). The reported benefits, however, depend on the stack design and operating conditions, and further validation at larger system scales is required before the method can be considered broadly applicable (Yu et al., 2023).

Modification of the cooling-channel geometry provides another route for increasing heat removal. Huang et al. investigated cooling channels containing asteroidal obstacles and reported a 20.07% increase in convective heat transfer together with an 8.7% increase in net power output under the conditions considered in their PEMFC study (Huang et al., 2024). These values represent the particular geometry, stack configuration, and operating conditions used in that investigation and should not be taken as universal improvements for PEMFC systems. The study nevertheless shows that introducing suitable flow disturbances can improve heat transfer, although the resulting pressure drop and pumping requirements must also be considered when assessing the overall system benefit (Huang et al., 2024).

Vapor chambers have likewise been investigated as a passive heat-spreading method for air-cooled PEMFCs. In a 10-cell stack, the vapor chamber removed nearly half of the generated heat under the reported operating conditions (Zhao et al., 2020a). By redistributing heat across the stack, the device reduced temperature non-uniformity without requiring a separate liquid-cooling loop. This approach may therefore be useful for compact and low-power systems, although its effectiveness at larger stack scales remains to be established (Zhao et al., 2020a).

Liquid cooling remains a critical approach for maintaining optimal operating temperatures in high-power PEMFC stacks. A recent survey on liquid cooling techniques explored various coolant flow configurations and the potential use of nanofluids as alternative coolants. The study found that nanofluids exhibit superior thermal conductivity compared to conventional coolants, improving heat dissipation while minimizing pumping power requirements. These advancements reinforce the importance of liquid cooling in ensuring the stability and efficiency of PEMFC stacks, particularly in automotive and stationary power applications (Bargal et al., 2020). Cooling plate design significantly influences the thermal performance of PEMFCs. Investigations into non-uniform flow channel designs have shown promising results in improving cooling efficiency, temperature uniformity, and pressure drop reduction. Unlike conventional straight channels, non-uniform designs help distribute coolant more effectively, preventing localized overheating and enhancing the overall cooling performance. These findings suggest that optimizing cooling channel geometry can be a simple yet effective method for enhancing the longevity and efficiency of PEMFC stacks (Sha et al., 2025). Comparative studies between single-phase and boiling flow conditions have demonstrated the advantages of utilizing boiling flow for PEMFC cooling. Boiling flow enhances heat transfer by leveraging latent heat effects, significantly reducing thermal gradients within the stack. This approach prevents excessive temperature variations, which can degrade membrane performance over time. As a result, boiling flow cooling is emerging as a viable alternative to conventional liquid cooling techniques, particularly in high-power applications where efficient thermal management is critical (Rajamony et al., 2026). Inspired by Honda’s Clarity fuel cell vehicle, a novel cooling strategy was developed using a 3D multiphase non-isothermal model. The study revealed that optimizing the heat transfer coefficient between the coolant and the stack can effectively mitigate local overheating issues, enhancing overall cell performance. This approach provides valuable insights into real-world applications of advanced cooling designs, paving the way for future improvements in automotive fuel cell thermal management (Bello et al., 2025). The diagram of the liquid cooling technique is shown below in Figure 5.

4.2 Colloidal stability and interfacial behaviour of nanostructured coolants

The practical performance of a nanostructured coolant depends not only on the intrinsic thermal properties of the dispersed material but also on its ability to remain sufficiently stable during storage and prolonged circulation. Nanoparticles suspended in a base fluid are subjected to competing interactions that can promote either dispersion or aggregation. Particle size, surface chemistry, concentration, pH, temperature, and the physicochemical properties of the base fluid consequently influence the stability and transport behaviour of the resulting colloidal system (AlMuhaysh et al., 2025).

Aggregation and sedimentation remain major limitations in the application of nanofluids to PEMFC cooling circuits. The formation of larger particle clusters can alter the effective thermal conductivity and viscosity of the coolant while increasing the possibility of deposition within narrow flow channels. Progressive deposition may modify local flow resistance, reduce heat-transfer effectiveness, and contribute to non-uniform coolant distribution (Babar et al., 2025). These effects are particularly important in PEMFC stacks because the coolant must circulate repeatedly through channels and manifolds while maintaining predictable thermal, hydraulic, and electrical properties. Surface modification and the use of dispersing agents have therefore been investigated to improve colloidal stability. Appropriate surface functionalisation can reduce attractive interactions between particles and improve compatibility with the selected base fluid. Nevertheless, additives introduced to stabilise a suspension may also alter viscosity, electrical conductivity, chemical compatibility, and environmental behaviour. Stability enhancement should consequently not be evaluated independently of the overall coolant requirements (Sha et al., 2025).

Colloidal stability is primarily governed by the balance between attractive van der Waals forces and electrostatic repulsive forces as described by the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. Stable nanofluids generally exhibit zeta-potential magnitudes exceeding approximately ±30 mV, whereas lower values often indicate increased susceptibility to particle aggregation. Long-term stability may also be affected by sedimentation, Brownian motion, Ostwald ripening, and particle agglomeration during repeated thermal cycling. To enhance dispersion stability, surfactants and dispersants including sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide (CTAB), polyvinylpyrrolidone (PVP), and oleic acid have been widely employed depending on nanoparticle chemistry. Oxide nanoparticles frequently rely on electrostatic stabilization, whereas carbon-based nanomaterials often require steric stabilization because of their hydrophobic surfaces. Hybrid nanofluids typically require optimized combinations of dispersants to maintain long-term colloidal stability without significantly increasing viscosity or reducing thermal conductivity.

Long-term stability represents a particularly significant research gap. Many reported nanofluid investigations evaluate freshly prepared samples or short operating periods, whereas practical PEMFC coolant systems require prolonged circulation under repeated heating and cooling cycles (Rajamony et al., 2026). Changes in particle size distribution, surface chemistry, pH, and state dispersion during ageing may progressively modify coolant performance. Reliable evaluation therefore requires complementary characterisation approaches, including particle-size analysis, sedimentation observation, zeta-potential measurement, rheological assessment, and monitoring of thermophysical properties before and after extended thermal cycling.

The development of practical colloidal coolants consequently requires a transition from the optimisation of initial thermal conductivity towards a broader assessment of dispersion durability. A nano-fluid that provides high heat-transfer enhancement immediately after preparation but undergoes rapid aggregation or deposition cannot be regarded as an effective long-term coolant (Bello et al., 2025). Colloidal stability must therefore be considered together with thermal performance, hydraulic behaviour, material compatibility, and environmental implications when advanced PEMFC coolant formulations are developed.

4.3 Integration of advanced coolants with stack-level thermal management

Optimized cooling strategies play a decisive role in enhancing the performance, durability, and operational stability of proton exchange membrane fuel cell (PEMFC) stacks. The effectiveness of a given cooling technique depends strongly on system scale, operating conditions, and design objectives; nevertheless, all approaches ultimately aim to maintain temperature uniformity, suppress thermal gradients, and mitigate degradation mechanisms that limit stack lifetime (Qianqian et al., 2026). Cooling uniformity has a direct and measurable influence on voltage stability and electrochemical performance. Non-uniform temperature distribution across the stack leads to local variations in reaction kinetics, membrane hydration, and current density, resulting in voltage fluctuations and accelerated component degradation. Air cooling, while structurally simple and lightweight, is mainly suitable for low- to medium-power PEMFC systems.

However, its limited heat removal capacity makes it less effective under high current densities, leading to localized hot spots that accelerate catalyst degradation and membrane thinning. Liquid cooling, by contrast, offers far superior heat dissipation due to the high thermal capacity and convective efficiency of liquid coolants, enabling more uniform temperature distribution across the stack; this directly minimizes membrane dehydration, catalyst layer corrosion, and gas diffusion layer (GDL) structural stress, making it the most effective choice for high-power stacks (e.g., 1 kW and above) despite added design complexity and parasitic pump power (Kumar et al., 2026). Heat spreaders, such as ultra-thin heat pipes or vapor chambers, provide a passive means of redistributing heat laterally across cells, thereby reducing temperature gradients and improving durability in compact or portable PEMFC configurations; their significance lies in their ability to enhance thermal uniformity without requiring additional active components, though their cooling capacity remains constrained by latent heat transport limits. Other than that, heat exchangers integrated into the cooling loop or coupled with waste heat recovery systems (e.g., Organic Rankine Cycles) extend the utility of PEMFCs beyond basic thermal regulation by converting excess thermal energy into secondary power or by maintaining stable coolant temperature under varying loads; this not only improves thermal management efficiency but also enhances overall system efficiency and lifetime, especially in stationary or vehicular applications where heat recovery is valuable. Taken together, these advancements underline that each cooling strategy provides targeted benefits, air cooling favors simplicity and lightweight design, liquid cooling ensures robust thermal control for high-power applications, heat spreaders enable passive temperature homogenization, and heat exchangers maximize system-level energy utilization, thereby highlighting the importance of selecting cooling methods in alignment with specific PEMFC stack requirements and operational contexts.

The thermal conductivity of the proton exchange membrane (PEM) and gas diffusion layer (GDL) is crucial for effective heat dissipation. The thermal conductivity of the PEM can be significantly improved by ordering Nafion molecules, which can double the thermal conductivity compared to amorphous membranes (Ren et al., 2024). Additionally, the thermal conductivity of the GDL increases with temperature and water content, showing a linear increase with water content. The in-plane thermal conductivity of the GDL decreases with increasing temperature but increases slightly with PTFE loading and MPL coating (Alhazmi et al., 2013). Besides thermal conductivities, the heat capacity of the coolant also plays a great role in dissipating heat from the stack. The heat capacity of the materials used in PEM fuel cells is not explicitly detailed in the abstracts. However, it is implied that the thermal properties, including heat capacity, are essential for maintaining temperature uniformity and effective thermal management (Li and Sundén, 2018; Atyabi et al., 2022). On the contrary, electrical conductivity is not required to have higher values, because high electrical conductivity in the coolant can cause a short circuit in the stack. Especially when using a metallic bipolar plate, which can conduct electricity easily as coolant flows across the current collector. This risky phenomenon can affect the overall stack efficiency as well as the life span of the stack, possibly to be shortened implicitly. Nevertheless, the electrical conductivity of the PEM and GDL is influenced by temperature and water content. Higher water content in the membrane increases its thermal conductivity, which indirectly affects its electrical conductivity by maintaining optimal hydration levels (Alhazmi et al., 2013).

Besides that, the viscosity of the coolant is also a significant parameter to be considered, as it would influence the stack energy efficiency through parasitic loss. The viscosity of the cooling fluids, particularly in liquid cooling systems, affects the pressure drop and flow characteristics within the cooling channels. Novel flow channel designs can improve cooling performance by optimizing the flow characteristics and reducing pressure drops (Li and Sundén, 2018), (Song et al., 2022). The less viscous of the coolant fluid, the higher the stack efficiency of the PEMFC to run, therefore, parasitic loss could be reduced owing to the decrement of energy needed by the control pump to flow the coolant. The thermal conductivity of the coolant plays a central role in enhancing heat dissipation across the PEMFC stack, ensuring uniform temperature distribution and mitigating localized hotspots. Equally important, the electrical conductivity of the coolant must remain sufficiently low to prevent parasitic current leakage or short-circuit risks, thereby safeguarding the electrochemical stability of the stack. While optimizing these two properties is essential for effective thermal management, the viscosity of the coolant further determines its flow behavior and pumping requirements; excessively high viscosity increases circulation resistance and energy consumption, whereas very low viscosity may compromise stable heat transfer efficiency. Therefore, achieving a balanced relationship between thermal conductivity, electrical conductivity, and viscosity is critical for designing high-performance coolant formulations in PEMFC applications.

Those cooling techniques affect stack performance in many aspects. Active and passive cooling strategies, along with more advanced multizone systems, each apply a distinctive influence on PEMFC stack performance. Liquid cooling, for instance, has been widely adopted in large-scale stacks due to its ability to ensure stability, durability, and improved performance (Qiu et al., 2020). Recent innovations, such as non-uniform flow channel designs in cooling plates, further enhance temperature uniformity and lower pressure drops, thereby advancing thermal management effectiveness (Li and Sundén, 2018). Air cooling, in contrast, simplifies system architecture by integrating oxygen supply with heat removal. Although less effective for high-power applications, its performance can be optimized through careful cathode channel design, where smaller channel widths and curved structures facilitate improved mass transfer and cell output (Qiu et al., 2020). In terms of passive methods, heat pipes represent a highly efficient solution as they provide effective thermal regulation with minimal parasitic load compared to liquid cooling, while simultaneously helping to retain higher membrane water content, which reduces resistance and enhances electrochemical performance (Singh et al., 2022). Similarly, vapor chambers exhibit exceptionally high thermal conductivity and isothermal properties, enabling rapid heat spreading and uniform temperature distribution, which makes them particularly attractive for low-power PEMFC configurations (Zhao et al., 2020b).

Beyond conventional active and passive approaches, multizone cooling systems offer an advanced pathway for superior stack performance. By dividing the stack into separate thermal zones and more precisely controlling the temperature distribution, these systems markedly improve current-density uniformity and mitigate reverse current generation, factors that directly translate into enhanced output stability and durability (Liu et al., 2024). Taken together, these studies indicate that maintaining uniform temperature distribution across the stack is the key determinant of performance, as it prevents localized hot spots, mitigates membrane dehydration, and slows down degradation mechanisms such as catalyst deterioration or membrane thinning (Liu et al., 2024; Li and Sundén, 2018; Atyabi et al., 2022). Cooling strategies that minimize thermal gradients, whether through liquid cooling, heat-spreading devices, or multizone designs, consistently improve both efficiency and long-term durability. Notably, multizone cooling has demonstrated particularly strong effects in enhancing voltage and current density uniformity (Liu et al., 2024). In summary, the selection and optimization of cooling techniques, alongside the careful balancing of thermal conductivity, heat capacity, viscosity, and electrical conductivity of the coolant, are central to designing high-performance PEMFC stacks across a wide range of power ratings. Advanced approaches such as liquid cooling, heat pipes, vapor chambers, and tailored flow field designs collectively highlight the critical role of thermal management in sustaining PEMFC performance. Figure 6a shows the most common cooling methods categories based on the literature. There are four primary cooling approaches in the field of PEMFCs: air cooling, passive cooling, liquid cooling, and phase change cooling. The cooling approach of a PEMFC stack is mainly selected based on its generated power (Figure 6b) (Choi et al., 2019). It should be noted that Figure 6b presents the power-based classification proposed in Ref. (Xing et al., 2022), whereas Table 1 provides the authors’ synthesized comparison of cooling technologies by integrating thermal performance, operational suitability, and representative application domains. Consequently, the stack power ranges presented in Table 1 should be interpreted as generalized engineering guidance rather than a direct reproduction of the classification shown in Figure 6b, and the two presentations are complementary rather than identical.

However, it is not the unique criteria, and the actual system requirements should also be considered. Generally speaking, the heat transfer coefficients with liquid cooling are much higher than those of air cooling for the same pumping power.

5 Composition, performance, and sustainability of colloidal coolants

Historically, various coolant strategies have been employed, with recent studies in PEMFC stack cooling showing that nanofluids, such as Al2O3, improve heat transfer by up to 12.7% compared with water (Zhang et al., 2019). Common coolants, including propylene glycol mixtures, have been analyzed for their thermal properties, revealing that higher concentrations can lead to dehydration of the membrane at elevated temperatures, thus impacting performance (Sahoo et al., 2023). The temperature of the coolant plays a critical role in component degradation, particularly affecting the membrane, catalyst layer, and bipolar plates, where uniform temperature distribution is essential to mitigate mechanical stress and corrosion (Choi JH. et al., 2024; Rajendran et al., 2024). Key performance metrics, such as voltage decay rate and power density, are directly influenced by coolant temperature, necessitating advanced temperature control strategies like variable flow rates and innovative cooling channel designs (Sun Q. et al., 2024). Furthermore, the interaction of coolant management with other operating conditions, including pressure and humidity, underscores the complexity of maintaining optimal performance in PEMFC stacks.

To keep system performance and to avoid component damage, proper coolant management is necessary in PEMFCs. Heat transfer and temperature are also affected by other media, such as water and types of refrigerant, which can serve as a medium, which is not an insoluble medium for a body (Yakubu et al., 2024). High working temperature of coolant results in increased mechanical stress and/or chemical attack on the membrane, catalyst layer, and bipolar plates (Zhang et al., 2025). There is an interdependence between the coolant temperature and fundamental performance parameters, including voltage decay rate and power density, and therefore there is a need for sound coolant management strategies (Chakraborty et al., 2024). Modern approaches in cooling management such as variation of coolant flow rates and geometry of cooling channels, have been examined to enhance performance in 1 kW PEMFC stacks (Li and Sundén, 2018; Wang et al., 2025). Also, combining the coolant regulation dynamics with other operating parameters, namely, pressure and humidity, highlights the complexity of achieving the desired output when changing the load (Liang et al., 2022).

Early strategies relied on air and water-based cooling systems, with water emerging as the dominant choice due to its superior thermal conductivity and heat capacity. However, water suffers from freezing and corrosion risks, which limit its application in harsh environments. To overcome these drawbacks, recent studies have explored advanced coolant formulations, including nanofluids and PCMs. Nanofluids, consisting of thermally conductive nanoparticles such as graphene, Al₂O₃, or SiO₂ dispersed in a base fluid, provide enhanced thermal conductivity, improved convective heat transfer, and better stability under variable loads. Meanwhile, PCMs can absorb and store excess heat through latent heat mechanisms, offering a passive means of temperature stabilization during transient operation. Apart from thermal conductivity, other properties such as viscosity, specific heat capacity, and chemical compatibility with PEMFC materials play a crucial role. High viscosity, for instance, may increase pumping power demand, while corrosive tendencies could shorten the stack lifetime. Thus, an ideal coolant must balance high heat transfer capability with low viscosity, stability against agglomeration, and compatibility with metallic bipolar plates (Kazemi-Varnamkhasti et al., 2023).

The operating temperature of the coolant strongly influences the performance and durability of PEMFC stacks. Elevated coolant temperatures can accelerate membrane dehydration, leading to higher ohmic resistance and reduced proton conductivity, while excessively low temperatures may cause electrode flooding, hinder gas diffusion, and slow electrochemical kinetics. Beyond immediate effects, long-term degradation mechanisms are also tied to coolant temperatures. Studies have reported that temperature fluctuations promote microcrack formation in catalyst layers, increase corrosion of metallic bipolar plates, and accelerate oxidation processes, all of which lower stack durability. Furthermore, voltage decay, a key indicator of fuel cell degradation, has been directly linked to poor thermal management. Maintaining a narrow and stable coolant temperature range has thus been identified as essential for ensuring high power density, stable voltage output, and extended stack lifespan (Sabawa and Bandarenka, 2021; Zhao et al., 2021; Liu Q. et al., 2023).

Apart from coolant selection, flow distribution plays a decisive role in thermal management. Conventional fixed flow rates may either undercool or overcool the stack, leading to inefficiencies. Adaptive flow control, where the coolant flow rate dynamically adjusts to the real-time thermal load, has emerged as a more efficient strategy, improving temperature uniformity while reducing parasitic pumping losses. Additionally, coolant channel design significantly influences thermal distribution. Serpentine channels offer good cooling efficiency but may suffer from higher pressure drops, while pin-fin and multi-zone configurations improve localized cooling and reduce hotspots. Computational fluid dynamics (CFD) simulations combined with experimental validation have consistently shown that optimized flow fields lead to better thermal homogeneity, enhanced reactant distribution, and improved durability. This highlights that coolant flow design must be treated as an integrated thermal optimization strategy rather than an afterthought (Li et al., 2023; Shetty et al., 2022; Chen et al., 2020). Thus, although geometric optimization and adaptive flow control offer tangible improvements in thermal uniformity, they must be complemented by system-level coolant management approaches that address the interlinked challenges of humidity balance, pressure stability, and load fluctuations. This shift from purely structural solutions toward intelligent, predictive cooling strategies represents the next step in achieving robust PEMFC performance.

Coolant management does not function in isolation; it must operate synergistically with other PEMFC parameters such as pressure, humidity, and load variation. For instance, humidity control is directly tied to coolant temperature, as excessive drying reduces membrane conductivity while condensation risks flooding the electrodes. Similarly, optimized pressure conditions can complement temperature control by minimizing gas crossover and stabilizing cell voltage. Load variations present an additional challenge, as they cause sudden changes in heat generation that can strain cooling systems. To address these dynamic conditions, researchers have proposed intelligent coolant management strategies, such as predictive thermal control algorithms and machine learning-based adaptive cooling. These approaches allow proactive adjustment of coolant flow and temperature in response to expected load changes, improving both efficiency and long-term durability. The integration of such smart cooling systems is increasingly recognized as a crucial step for advancing PEMFC stacks toward commercial viability in both stationary and mobile applications (Yu et al., 2022; Chen et al., 2022). As the quest for enhanced thermal management continues, the integration of advanced materials and technologies offers promising avenues for improving PEMFC performance. For instance, the application of smart materials that respond to temperature fluctuations could provide a dynamic response mechanism, adjusting their properties in real-time to optimize heat transfer efficiency. Additionally, the exploration of hybrid cooling systems that combine active and passive cooling strategies could further mitigate temperature extremes, leveraging both the high thermal conductivity of nanofluids and the latent heat storage capabilities of PCMs to create a more resilient system. Such innovations not only aim to enhance the operational stability of PEMFCs but also contribute to their commercial viability by addressing the challenges posed by environmental conditions and load variations, thereby ensuring a robust performance in diverse applications (Ghasemi et al., 2017; Raguman and Vedagiri, 2022). Among these strategies, nanofluids have emerged as particularly promising candidates, offering unique thermal and physical properties that directly address the limitations of conventional liquid coolants.

Nanofluids are engineered by dispersing nanoparticles into base fluids such as water, ethylene glycol, or propylene glycol, creating a suspension with significantly enhanced thermal conductivity and heat absorption capacity. These nanoscale modifications allow superior heat transfer efficiency compared to traditional coolants, thereby improving temperature regulation, reducing hotspots, and ultimately enhancing the durability of PEMFC stacks. Furthermore, the ability to tune nanofluid composition through particle type, concentration, and surface treatment provides flexibility in balancing thermal performance with viscosity and pumping requirements, making them a versatile solution for next-generation coolant systems. The inclusion of nanoparticles such as aluminum oxide (Al₂O₃) and silicon dioxide (SiO₂) significantly improves the thermal conductivity and heat absorption capacity of the base fluids. In the context of PEMFCs, the application of nanofluids has been explored to enhance heat dissipation efficiency. For instance, a study investigated the characteristics of hybrid Al₂O₃:SiO₂ nanofluids in the cooling plates of PEMFCs (Yu et al., 2022), revealing that these nanofluids exhibit superior thermal performance compared to single-component nanofluids, thereby offering improved cooling efficiency.

Furthermore, a comprehensive review highlighted that nanofluids effectively enhance the heat dissipation capacity in fuel cell vehicles (Kazemi-Varnamkhasti et al., 2023), suggesting their potential as advanced coolants in PEMFC thermal management systems. While nanofluids primarily enhance the active cooling capacity of PEMFC systems, PCMs represent a complementary approach by enabling effective passive cooling. Unlike nanofluids that improve heat transfer through enhanced thermal conductivity, PCMs regulate stack temperature by leveraging latent heat storage, thereby offering stability under fluctuating operating conditions. PCMs have garnered attention for their ability to absorb and release substantial amounts of latent heat during phase transitions, thereby maintaining thermal stability. In PEMFC applications, integrating PCMs facilitates passive cooling by absorbing excess heat during operation and releasing it during periods of lower thermal demand. This mechanism ensures a more uniform temperature distribution within the fuel cell stack, mitigating the risks associated with thermal hotspots. A review on the use of PCMs for thermal management in PEMFCs emphasized their potential to enhance passive cooling and maintain thermal stability (Chen et al., 2020), thereby improving the overall efficiency and lifespan of the fuel cells. Additionally, advancements in nano-enhanced PCMs have been explored to further optimize thermal response times and cycling stability (Huang et al., 2022), offering promising avenues for improved thermal management in PEMFCs. In addition to the choice of advanced coolants such as nanofluids and PCMs, the temperature of the coolant itself is a decisive factor in determining PEMFC efficiency and durability. Regardless of the coolant medium, improper temperature regulation can accelerate component degradation or hinder ionic conductivity, underscoring the importance of precise thermal control. The temperature of the coolant plays a pivotal role in determining the efficiency, durability, and power output stability of PEMFC stacks. Maintaining the coolant within an optimal temperature range is essential to ensure efficient electrochemical reactions and to prevent component degradation. Elevated coolant temperatures can lead to membrane dehydration and catalyst layer degradation, adversely affecting the performance and lifespan of the fuel cell. Conversely, excessively low coolant temperatures may result in reduced ionic conductivity and increased activation losses. Therefore, precise control of coolant temperature is imperative to balance these factors and maintain optimal PEMFC operation. A study on the characteristics of temperature rise and coolant flow rate control during PEMFC malfunctions highlighted the significance of coolant temperature management in preventing performance degradation and ensuring stable power output (Zhao et al., 2021).

Beyond coolant selection and temperature regulation, effective control of coolant flow is equally critical for ensuring uniform thermal distribution within PEMFC stacks. Optimizing flow rate and pressure drop not only enhances heat dissipation efficiency but also prevents localized overheating, complementing the benefits offered by advanced coolant formulations. Effective coolant flow control is vital for uniform heat dissipation and the prevention of overheating in PEMFC stacks. Optimizing the flow rate and managing pressure drops within the cooling system are crucial to achieving efficient thermal management. Strategies such as designing flow channels to minimize pressure losses and employing variable flow rate controls have been investigated to enhance cooling efficiency. For instance, research on the characteristics of temperature rise and coolant flow rate control during PEMFC malfunctions demonstrated that adjusting the coolant flow rate in response to temperature fluctuations effectively maintains uniform cooling and prevents overheating (Ghasemi et al., 2017). Additionally, a study on the thermal management of PEMFCs using hybrid Al₂O₃:SiO₂ nanofluids in cooling plates indicated that optimizing coolant flow parameters significantly enhances heat dissipation efficiency (Li et al., 2023), thereby improving the overall performance of the fuel cell system. Comparable CFD investigations on plate heat exchangers have likewise demonstrated that appropriate channel design and flow distribution significantly improve cooling effectiveness and temperature uniformity, highlighting the importance of heat exchanger optimisation in thermal management applications (Agarwal, 2021).

Building on conventional flow management approaches, recent research has advanced towards adaptive cooling strategies that dynamically respond to real-time operating conditions. By integrating intelligent control systems with variable flow rates, these adaptive methods elevate PEMFC thermal management to a more reliable and efficient level, particularly under fluctuating load demands. Adaptive cooling strategies, incorporating variable coolant flow rates and intelligent control systems, have been developed to respond dynamically to real-time heat generation within PEMFC stacks. By monitoring operating conditions and adjusting coolant flow rates accordingly, these systems ensure optimal thermal management under varying loads. The integration of sensors and control algorithms enables precise regulation of coolant distribution, enhancing both efficiency and reliability. For example, a study on hydrogen PEMFC systems for automotive applications implemented a proportional-integral-derivative (PID) control scheme for the fan cooling system (Raguman and Vedagiri, 2022), maintaining the stack temperature within desired limits under varying load conditions. This adaptive approach not only prevents overheating but also contributes to the overall efficiency and longevity of the PEMFC system. Taken together, the progressive developments in coolant formulation, temperature regulation, flow control, and adaptive strategies highlight a multifaceted approach to PEMFC thermal management. Each technique addresses different aspects of heat dissipation, and their integration offers a pathway toward achieving higher efficiency, durability, and commercial viability of PEMFC systems. In conclusion, advancements in coolant composition and flow optimization have significantly enhanced the thermal management of PEMFCs. The utilization of nanofluids as advanced coolants, the integration of PCMs for passive cooling, meticulous control of coolant temperature and flow parameters, and the adoption of adaptive cooling strategies collectively contribute to improved heat dissipation, thermal stability, and overall performance of PEMFC stacks. These innovations play a crucial role in addressing overheating challenges and promoting the widespread adoption of PEMFC technology in various applications. The performance of the PEMFC stack is not just affected by properties of the coolant but also impacted by the coolant flow configurations.

There are two types of configurations, which are U-type and Z-type configurations. For U-type, it exhibits superior single-cell consistency and improves temperature uniformity. At high current densities, it shows a lower maximum voltage difference (38.12 mV) compared to the Z-type configuration (117.52 mV), indicating better performance and consistency, as proven by (Deng et al., 2024) and (Zhang L. et al., 2024). For Z-type, in contrast, Deng et al. found that there were significant dead zones near the outlet side of each cell’s flow field, leading to concentration polarization and higher voltage differences. The illustration of these configurations, U-type and Z-type are shown in Figure 7. There were also differences in performance between counter-flow and co-flow configurations. Counter-flow configuration could enhance electrochemical reaction rates and improve water distribution in the membrane, leading to better performance (Zhang Y. et al., 2024). Meanwhile, the co-flow configuration is beneficial for raising the temperature along the cathode gas flow direction and reducing the risk of flooding near the cathode outlet (Liu X. et al., 2023). Apart from that, the stack performance can also be improved by increasing the coolant flow rate and coolant velocity. A higher coolant flow rate can reduce stack temperature and improve the temperature uniformity, similar to how higher coolant velocity would improve temperature consistency, especially in a U-type configuration (Deng et al., 2024).

However, these advantages come with some risks, such as flooding might happen near the cathode outlet when the coolant flow rate is high, and the concentration polarization might worsen at higher coolant velocity (Zhang L. et al., 2024; Liu X. et al., 2023). There were some innovative cooling strategies, like the mixed-cooling pathway and serial cooling concept. For the mixed-cooling pathway, it achieves higher load capacity, enhanced power generation performance, and superior thermal performance compared to conventional air-cooled and split-cooling stacks. It also results in lower additional power consumption and more uniform voltage distribution (Yang et al., 2025). Meanwhile, the serial cooling concept allows for a significant reduction in coolant mass by increasing the total temperature difference over the coolant, although it may result in slightly less efficient and heavier fuel cell units (Link et al., 2022). The stack performance also considers the designs of the cooling plates placement and the cooling channel as well. (Sasmito et al., 2011) prove a strong correlation between stack performance and the placement of coolant plates. Optimal performance is achieved with one coolant plate between each unit cell, while performance drops as more cells are placed between coolant plates. Song et al. discovered novel non-uniform flow channel designs significantly enhance cooling performance, temperature uniformity, and heat transfer capacity (Li and Sundén, 2018; Song et al., 2022). Above all, temperature management is the most essential aspect to control to achieve optimal stack performance and lifespan. It was reported that multi-spiral flow fields and honeycomb structures improve temperature uniformity (Song et al., 2022). Without uniform temperature, the PEMFC stack would be negatively impacted by the high uncontrolled temperatures, thus requiring a reasonable distribution of cooling channels to mitigate this effect (Song et al., 2022; Zhang L. et al., 2024).

Different coolant flow configurations, including U-type, Z-type, counter-flow, and co-flow, along with innovative cooling strategies and optimal placement of cooling plates, play a crucial role in enhancing the performance, consistency, and thermal management of PEMFC stacks. Adjusting coolant flow rates and velocities, and employing novel cooling channel designs, can further optimize the cooling efficiency and overall stack performance. While flow field design and cooling channel configurations largely determine the distribution of heat within the stack, the effectiveness of these strategies ultimately depends on the choice and management of the coolant itself. The selection of an appropriate coolant therefore requires consideration of multiple interrelated thermophysical and operational parameters. Although advanced coolants substantially improve heat dissipation, thermal enhancement should not be considered independently of hydraulic performance. Increasing nanoparticle concentration generally improves thermal conductivity but also increases viscosity, resulting in higher pressure drop and pumping power requirements. Similarly, highly conductive nanoparticles may enhance heat transfer but require careful consideration of corrosion behaviour, electrical conductivity, and compatibility with stack materials. Consequently, practical coolant selection requires balancing thermal performance with hydraulic efficiency, electrochemical stability, and long-term durability rather than maximising any single thermophysical property. Thus, coolant management has become a central aspect of PEMFC thermal regulation, complementing innovations in flow pathways and cooling plate arrangements. Coolant management has long been recognized as a critical factor in the thermal regulation of PEMFC stacks. Early strategies primarily relied on air- and water-based cooling systems, with water emerging as the dominant choice due to its superior thermal conductivity and heat capacity. However, recent advancements have explored alternative coolants such as nanofluids and PCMs, which exhibit enhanced thermal properties and improved heat dissipation efficiency. Comparative studies conducted between 2021 and 2024 have analyzed various coolants, focusing on their ability to maintain optimal stack temperatures while minimizing energy losses (Cornet et al., 2025). Moreover, research has emphasized that coolant fluids must not only enhance heat transfer but also prevent operational issues such as freezing, corrosion, or contamination within the fuel cell system (Yakubu et al., 2024). The impact of coolant temperature on PEMFC component degradation has been extensively studied, particularly concerning membrane integrity, catalyst stability, and bipolar plate corrosion. Elevated coolant temperatures accelerate membrane dehydration, which increases ohmic resistance and reduces proton conductivity (Mitincik and Yazici, 2026). Conversely, excessively low temperatures may induce electrode flooding, hinder gas diffusion, and reduce reaction kinetics. Studies indicate that maintaining an optimal coolant temperature range is therefore crucial in preventing mechanical stress, chemical degradation, and material corrosion (Chen et al., 2023). Additionally, long-term experiments have shown that fluctuating coolant temperatures contribute to microcrack formation in catalyst layers and exacerbate bipolar plate oxidation, further reducing fuel cell efficiency and durability (Seo et al., 2020).

Coolant temperature directly influences several key performance metrics in PEMFC stacks, including voltage decay rate, power density, and overall system efficiency. Voltage decay is often used as a diagnostic indicator of degradation, and studies demonstrate that improper thermal management accelerates the loss of electrochemical activity in the catalyst layer (Yousfi-Steiner et al., 2008). Furthermore, experiments conducted on a 1 kW PEMFC stack revealed that stable coolant temperature significantly enhances power density by ensuring uniform reactant distribution and reducing energy losses (Nguyen et al., 2024). Computational fluid dynamics (CFD) simulations reinforce these findings, demonstrating that optimized cooling strategies improve thermal distribution and extend fuel cell lifespan (Gößling et al., 2021). Recent research has proposed advanced temperature control techniques for PEMFC stacks across laboratory-scale and practical operating conditions, including demonstrations using 1 kW systems (Chen et al., 2024). One effective strategy involves variable coolant flow rate adjustments, where dynamic cooling control is applied in response to real-time thermal load variations. Studies have shown that adaptive flow regulation enhances temperature uniformity while minimizing parasitic power losses associated with excessive coolant circulation (Bargal et al., 2020). Additionally, novel cooling channel design such as serpentine, pin-fin and multi-zone configurations have demonstrated substantial improvements in heat dissipation efficiency and pressure drop reduction (Wang et al., 2026). The use of advanced coolant materials has also gained attention. For instance, nanofluids containing thermally conductive nanoparticles suspended in conventional coolants enhance thermal conductivity and convective heat transfer (Madheswaran et al., 2023), while PCMs integrated within cooling systems absorb excess heat via latent heat storage, thereby stabilizing stack temperatures during peak loads (Li and Sundén, 2018). Comparative studies suggest that these techniques provide superior thermal regulation compared to traditional water-based cooling, positioning them as promising solutions for next-generation PEMFC systems (Zhou et al., 2022). Figure 8 shows the diagram chart of coolant strategies that researchers may take into consideration.

Importantly, coolant management does not function in isolation but interacts dynamically with other operating conditions such as pressure, humidity, and electrical load variations. Studies highlight that synergistic control of temperature and pressure reduces degradation rates and improves voltage stability (Cigolotti et al., 2021). Likewise, humidity regulation plays a pivotal role in maintaining membrane hydration, as both excessive drying and condensation adversely affect performance. Integrating temperature and humidity control strategies has been shown to improve long-term stability and system efficiency (Zhang Y. et al., 2024). Moreover, fluctuating electrical loads introduce additional challenges for thermal management. Rapid changes in heat generation require adaptive cooling systems to prevent thermal stress-induced degradation. To address this, predictive algorithms combined with real-time temperature monitoring have been proposed (Yu et al., 2022). Looking forward, machine-learning-based thermal control systems may further enhance adaptability and reliability in dynamic PEMFC operating environments. As a summary, Table 4 tabulates the important criteria for selecting coolants comparable to different mixtures and types.

TABLE 4. Comparative comparison of coolant types for PEMFC thermal management systems.

Representative ranges for nanofluids are adapted from recent experimental and review studies on PEMFC, and heat-transfer nanofluids. Actual values vary with nanoparticle material, particle size, concentration, base fluid, temperature, and dispersion stability (Madheswaran et al., 2023; Bhattad et al., 2023; Ind et al., 2025; Sun L. et al., 2024; Tao et al., 2023).

Dynamic viscosity values are representative values at approximately 25 °C. Actual coolant properties depend on coolant formulation, operating temperature, nanoparticle loading, particle morphology, surfactant type, and measurement conditions.

5.1 Environmental implications and lifecycle challenges

The environmental performance of nanostructured coolants cannot be determined solely from improvements in heat-transfer efficiency. A broader assessment must consider the origin and quantity of raw materials, energy and chemical requirements during nanoparticle production, preparation of the dispersion, operational lifetime, potential release during use and maintenance, and management of the coolant at the end of its service life. These factors are particularly relevant when advanced coolants are proposed as components of sustainable energy technologies.

From a sustainability perspective, the benefits associated with enhanced thermal management should be evaluated alongside the environmental burdens associated with nanoparticle synthesis, coolant preparation, operational use, recovery, recycling, and end-of-life disposal. Consequently, lifecycle assessment has become an important complementary approach for determining whether the thermal advantages of advanced nanofluids outweigh their environmental impacts (Sha et al., 2025; Rajamony et al., 2026; Bello et al., 2025).

Representative life-cycle assessments indicate that the environmental burden associated with nanofluids depends strongly on nanoparticle synthesis routes and concentrations. Conventional production of oxide nanoparticles such as Al₂O₃ and TiO₂ is energy intensive, with reported cradle-to-gate energy demands typically ranging between approximately 50–200 MJ kg^-1 and corresponding greenhouse gas emissions of about 4–15 kg CO₂-eq kg^-1 depending on synthesis method and electricity mix. Carbon nanomaterials, particularly carbon nanotubes (CNTs), generally exhibit substantially higher embodied energy, often exceeding 500 MJ kg^-1 with associated emissions exceeding 20–40 kg CO₂-eq kg^-1 due to high-temperature manufacturing processes. Beyond production impacts, environmental risks arise from nanoparticle release during preparation, operation, maintenance, and end-of-life disposal. Experimental studies have reported nanoparticle concentrations in wastewater ranging from several µg L^-1 to mg L^-1 depending on handling conditions, while ecotoxicological investigations indicate that certain engineered nanoparticles may adversely affect aquatic microorganisms and algae at relatively low exposure concentrations. Consequently, recovery, recycling, and closed-loop coolant management strategies should be incorporated into PEMFC cooling system design to minimize environmental release. Future research should integrate comprehensive life-cycle assessment (LCA), techno-economic analysis (TEA), and environmental risk assessment to evaluate the overall sustainability of nanofluid-based PEMFC thermal management.

Nanoparticle production routes differ considerably in their material and energy requirements. Conventional preparation processes may involve elevated temperatures, multiple chemical reagents, surface-treatment agents, and purification stages. Consequently, the environmental advantages obtained through improved PEMFC thermal regulation may be partially offset when coolant production has a substantial resource or energy requirement. The development of alternative preparation methods, including lower-temperature processes and the use of bio-derived feedstocks, therefore represents an important research direction. However, claims of environmental superiority should be supported by systematic assessment rather than inferred exclusively from the renewable origin of a precursor material.

Operational durability also has direct lifecycle implications. Poorly stable colloidal dispersions may require frequent coolant replacement and generate additional waste streams. Nanoparticle deposition can further reduce cooling-system efficiency or contribute to component degradation, potentially shortening stack or balance-of-plant service life. Conversely, a stable coolant that improves thermal uniformity and reduces thermally induced degradation may provide indirect environmental benefits by extending component lifetime and reducing material replacement. The relationship between coolant stability, system durability, and resource consumption should therefore be incorporated into sustainability assessments.

Potential nanoparticle release represents another unresolved issue. Leakage, maintenance operations, coolant replacement, accidental discharge, and end-of-life handling may introduce nanostructured materials into environmental systems. The behaviour of released particles can differ from that of the original coolant because aggregation, surface transformation, dissolution, and interaction with other substances may occur during use and following environmental exposure. The environmental fate of nanostructured coolant components should consequently be evaluated together with their thermal performance.

Recovery and disposal remain insufficiently addressed in existing literature. Strategies for separating nanoparticles from spent coolant, regenerating base fluids, recovering valuable materials, and preventing uncontrolled release could improve the lifecycle performance of advanced coolant systems. Design for recovery should ideally be considered during coolant formulation rather than after commercial deployment. Such an approach would encourage the selection of materials and additives that provide adequate operational stability without creating unnecessary barriers to subsequent treatment or recycling.

Lifecycle assessment provides a useful framework for comparing conventional and nanostructured coolants because it can identify trade-offs between enhanced operational performance and impacts occurring during material production and end-of-life management. Nevertheless, comprehensive lifecycle datasets for PEMFC nanofluids remain scarce. Future investigations should combine thermal and hydraulic performance measurements with material inventories, coolant lifetime data, energy requirements, replacement frequency, recovery potential, and end-of-life scenarios. Without these considerations, it remains difficult to determine whether improvements observed during laboratory heat-transfer experiments translate into genuine environmental benefits at the system level.

Sustainable development of colloidal PEMFC coolants therefore requires a multidimensional evaluation framework. Thermal conductivity enhancement should be considered alongside viscosity, pumping demand, electrical conductivity, corrosion, dispersion stability, toxicity, environmental fate, service lifetime, and recovery potential. Integrating these criteria will enable more meaningful comparison of candidate coolant formulations and reduce the risk of shifting environmental burdens from PEMFC operation to coolant production or disposal.

6 Conclusion and future recommendations

This review systematically examined recent progress in coolant-based thermal management strategies for PEMFC stacks, with emphasis on laboratory-scale and medium-power systems, and their implications for performance, durability, and operational stability. The analysis confirms that effective thermal control is indispensable for mitigating temperature non-uniformity, preserving membrane hydration, limiting catalyst degradation, and suppressing bipolar plate corrosion, thereby directly influencing stack efficiency and service life. Among the cooling techniques reviewed, air cooling remains suitable for low-power and portable applications due to its simplicity and low parasitic load, though it is limited at elevated current densities. Liquid cooling via deionized water and glycol-based mixtures dominates mid-to-high power implementations given their reliability and material compatibility. PCM cooling offers effective passive thermal buffering through isothermal heat absorption, naturally promoting temperature uniformity and hotspot suppression without additional pumping. Heat spreader configurations integrated within bipolar plate or GDL assemblies further redistribute localized thermal loads and reduce peak temperature gradients across the membrane-electrode assembly. Nanofluid-based coolants, spanning oxide-based, carbon-based, and hybrid formulations, deliver superior heat transfer performance relative to conventional base fluids, particularly within optimized flow-field and multi-zone cooling architectures. Collectively, these strategies enhance tolerance to high current densities and transient loads, directly supporting voltage stability and extended stack lifetime.

Despite encouraging laboratory-scale results, significant challenges remain in translating advanced cooling media into commercially viable PEMFC systems. Nanofluid-based coolants face unresolved issues related to long-term dispersion stability, viscosity-induced pumping losses, corrosion risks, and compatibility with stack materials under realistic electrochemical environments. PCM systems, while thermally advantageous, present challenges in volumetric expansion management, thermal cycling fatigue, and integration with existing stack architectures without compromising gas diffusion layer porosity or membrane compression uniformity. Addressing these limitations is essential before large-scale adoption can be realized. Furthermore, most reported performance improvements have been demonstrated under controlled laboratory conditions using relatively small PEMFC stacks and limited operating durations. Commercial fuel cell systems are subjected to dynamic load variations, repeated thermal cycling, extended service periods, and stricter economic constraints. Accordingly, greater emphasis should be placed on large-scale validation under realistic operating conditions to establish the long-term durability, reliability, and cost-effectiveness of advanced coolant technologies. In parallel, the development of next-generation coolant formulations with balanced thermophysical properties and chemical stability should remain a research priority. Hybrid nanofluids incorporating functionalized nanostructures, such as graphene-based materials, layered silicates, or synergistic multi-component additives, represent a promising direction, provided that durability, manufacturability, and system-level integration are rigorously evaluated. Moreover, coupling advanced coolant materials with intelligent thermal management architectures and predictive control strategies will be critical for ensuring robust operation under dynamic load profiles.

Based on the critical analysis presented in this review, the following research priorities are proposed:

• Improve the long-term stability and durability of advanced coolants through systematic investigation of nanoparticle dispersion stability, corrosion behaviour, fouling mechanisms, and compatibility with PEMFC stack materials under realistic operating conditions.
• Develop standardized evaluation protocols for coolant characterization, including thermophysical properties, electrochemical compatibility, corrosion resistance, and long-duration stack testing, to enable reliable comparison across different studies and accelerate technology transfer.
• Advance hybrid thermal management systems by integrating nanofluids, phase change materials, optimized coolant flow fields, and intelligent cooling architectures to improve temperature uniformity while minimizing parasitic power consumption.
• Validate advanced cooling technologies under practical operating conditions, including dynamic load cycling, transient thermal events, multi-cell and multi-kilowatt stacks, and long-term durability testing to bridge the gap between laboratory investigations and commercial deployment.
• Integrate real-time monitoring with predictive thermal management, combining embedded sensors, data-driven modelling, artificial intelligence, and digital twin technologies to achieve adaptive coolant control, early fault detection, and enhanced operational reliability.

Overall, continued advances in coolant formulation, cooling system integration, and intelligent thermal management will play a pivotal role in improving PEMFC efficiency, durability, and commercial viability. These advances are expected to accelerate the commercialization of reliable, durable, and energy-efficient PEMFC systems. Figure 9 summarises the major research gaps identified in this review and provides a roadmap to guide future investigations.

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Footnotes

Edited by: Daniela Šojić Merkulov, University of Novi Sad, Serbia

Reviewed by: Vishal Gupta, Thapar Institute of Engineering and Technology (Deemed to be University), India

Dedi Rohendi, Universitas Sriwijaya Jurusan Kimia, Indonesia