Search Results (1,635)

The cathodic oxygen reduction reaction (ORR) remains a major kinetic barrier to high-efficiency proton exchange membrane fuel cells (PEMFCs), motivating the search for electrocatalysts that combine high activity, low metal usage, and long-term durability. This review examines single-atom catalysts (SACs) as an emerging platform for fuel-cell cathodes with particular emphasis on how atomic-level design, ORR mechanism, and practical deployment barriers are interrelated. The review discusses the key ORR pathways, intermediate binding principles, and scaling constraints that govern cathodic performance, and examines how metal-center selection, coordination-environment engineering, support regulation, synergistic multi-site construction, and morphology-controlled synthesis can be used to tune intrinsic activity and stabilize isolated active sites. It further highlights mechanistic insights from theoretical and operando studies, with emphasis on structure–activity relationships, dynamic active-site evolution, and approaches to mitigate scaling limitations. Major barriers to practical deployment, including carbon corrosion, demetalization, agglomeration, peroxide/reactive oxygen species attack, and the persistent gap between half-cell metrics and membrane electrode assembly performance, are also critically assessed. Rather than treating these topics separately, this review discusses them as connected factors that together determine the viability of SAC-based fuel-cell cathodes. Full article

This study investigates the enhancement of hydrogen production efficiency in water electrolysis through the application of external magnetic fields. A series of controlled experiments were conducted using four distinct electrode materials—stainless steel (SS), low-carbon steel (LCS), titanium (Ti), and platinum-plated titanium (Ti/Pt)—to identify the optimal configuration for maximizing gas output. The research evaluated the influence of electrolyte concentration (KOH), current density, and magnetic field intensity ranging from 0 to 1800 G. Our findings indicate that the application of a 200 G magnetic field leads to a notable 6% increase in the rate of gas production compared to non-magnetized conditions. Specifically, a magnetic field oriented parallel to the electrode plates outperformed a perpendicular orientation by approximately 5%, a phenomenon attributed to the Lorentz force facilitating ionic mass transfer and gas bubble detachment. Furthermore, the integration of ion-exchange and proton-exchange membranes (MC-3470 and N-117) effectively isolated the anodic and cathodic products, elevating hydrogen purity from 67.4% to approaching 100% without compromising electrolysis efficiency. These results demonstrate that the strategic coupling of moderate magnetic fields with optimized electrode configurations provides a promising pathway for improving the efficiency and cleanliness of hydrogen production, which is essential for its role as a sustainable energy carrier. Full article

Due to the high sensitivity of proton exchange membrane fuel cells (PEMFCs) to feed gas contamination through balance of plant (BOP) materials, in situ qualification plays a crucial role to secure performance, durability, and economic viability. To be able to deliver verified and accurate qualification results it is necessary to analyze the test method in detail and to perform repetitions on certain measurements. This work focuses on validation of an in situ material qualification test method in terms of measuring precision on a previously developed test bench and statistical significance of collected data. As a statistical approach t-test was used to calculate confidence intervals based on a sample size of 15 reference measurements with the same parameters and setup but variable membrane electrode assemblies (MEAs). The results show substantial reduction in confidence intervals with growing measurement’s sample size clearly quantifying accuracy of the analyzed methodology. The precision of the test method, as indicated by the calculated confidence intervals of irreversible voltage loss is approximately 1.21 mV, corresponding to a relative deviation of about 0.17% with respect to the calculated mean value across all steady-state phases (SSPs). This approach also provides an insight into the natural degradation behavior of the tested MEAs. The calculated effects can serve as a basis for design of experiments (DOE) in future test series. Full article

The microporous layer (MPL) is a key functional component in proton exchange membrane fuel cells (PEMFCs), and clarifying the quantitative relationship between its microstructure and mass transport properties is essential for improving cell performance. In this study, a three-dimensional MPL model was developed using a stochastic reconstruction method, and, together with a random walk algorithm, was employed to systematically investigate the effects of porosity, carbon sphere radius, maximum overlap ratio, seed ratio, and polytetrafluoroethylene (PTFE) content on permeability, effective diffusivity, and tortuosity. The results reveal that increasing porosity reduces tortuosity from 1.7 to 1.3, while permeability and effective diffusivity increase by factors of approximately 6.5 and 1.8, respectively. As the carbon sphere radius increases, tortuosity decreases from 1.55 to 1.35, accompanied by an increase in permeability from 2 × 10⁻¹⁶ m² to 20 × 10⁻¹⁶ m². Moreover, increasing the PTFE content raises permeability from 5 × 10⁻¹⁶ m² to 22.5 × 10⁻¹⁶ m², corresponding to an enhancement by a factor of approximately 4.5. The high-accuracy fitting equations obtained from the simulation results provide theoretical guidance for the microstructural design and optimization of MPLs, which can enhance oxygen transport and water management, reduce mass transport losses, and thereby benefit high-power-density operation and the overall efficiency of PEM fuel cells. Full article

The hydrophilicity of the porous transport layer (PTL) critically influences the mass transport overpotential and overall efficiency of a proton exchange membrane water electrolyzer (PEMWE). In this study, titanium felts with three distinct levels of hydrophilicity are systematically characterized and evaluated electrochemically. A novel bilayer gradient hydrophilic titanium felt structure is designed, resulting in notable performance improvements: the average cell voltage decreases by 12.92%, and the overpotential is reduced by 9.94–18.03% across a current density range of 0.1–1.6 A·cm⁻². High-speed imaging reveals that the gradient hydrophilic structure effectively regulates bubble dynamics, nearly eliminating annular flow bubbles, reducing the proportion of slug flow bubbles by 40.78%, decreasing the bubble detachment diameter by 28.26%, and enhancing bubble displacement by 51.03% compared to that of untreated titanium felt. These results demonstrate that gradient hydrophilic structures can significantly enhance PEMWE performance, offering a promising strategy and a theoretical foundation for optimizing mass transfer in electrolytic systems. Full article

Proton exchange membrane fuel cell vehicles (PEMFCVs) have attracted widespread attention in recent years. However, there are many challenges existing in the development, such as the durability and economy of the fuel cell system (FCS). In this investigation, a fuzzy energy management strategy based on Grey Bernoulli Prediction (FEMS-GBP) is proposed to mitigate these two issues. Grey Bernoulli Prediction (GBP) is used to predict the FCS short-term future power demand with a low calculation amount, which is suitable for real-time on-board applications in PEMFCVs. Therefore, FEMS-GBP can proactively adjust FCS output power to reduce large load change times during PEMFCV operation, thereby improving FCS durability. Fuzzy control is employed to accomplish the energy management task between the FCS and the battery for better fuel economy. Numerical simulations and experiments under different vehicle driving cycles are carried out to evaluate the performance of FEMS-GBP. By comparing it with two other conventional energy management strategies, FEMS-GBP is demonstrated to be feasible and effective, as it achieves favorable performance in balancing durability and economy, especially under practical driving conditions. Full article

Per- and polyfluoroalkyl substances (PFAS) have found wide application in proton exchange membrane fuel cells (PEMFCs) and water electrolysers (PEMELs), thanks to their exceptional chemical and thermal stability. However, their environmental persistence and growing regulatory pressure—particularly from the European Union—have made the transition to PFAS-free components a priority. This work reviews current advancements in alternative materials that can guarantee the same performance or maybe improve it. Although several non-fluorinated materials have demonstrated initial performance close to PFAS-based benchmarks, significant challenges remain. These include limited long-term stability, difficulties for new materials to fit into existing stack architectures, and the lack of standardized testing protocols. Nevertheless, recent efforts have successfully demonstrated a PFAS-free PEM electrolyser stack at TRL 4, validating the technical feasibility of full PFAS substitution. Achieving commercial readiness will require parallel progress in materials development and industrial scalability. This review highlights the possibility that hydrogen technologies, such as fuel cells and electrolysers, which are called upon to support the energy transition towards a more sustainable future, are themselves truly environmentally friendly, thus making their use as green as possible. Full article

This study addresses the optimal scheduling of a proton exchange membrane fuel cell (PEMFC)-based building combined cooling, heating, and power (CCHP) system, aiming to improve operational efficiency and flexibility under coupled electricity–thermal–cooling demands and load uncertainty. A physics-informed scheduling environment was developed using component models and multi-energy balance constraints, including a PEMFC with waste-heat recovery, a lithium bromide absorption chiller, a reversible heat pump with condenser heat recovery to thermal storage, a battery energy storage system, and a hot-water thermal storage tank. The dispatch problem was formulated as a Markov decision process and solved using deep reinforcement learning with TD3; performance was evaluated on typical summer and winter days, and robustness was tested by generating 100 scenarios with 30% demand perturbations. The results show that TD3 learns coordinated multi-energy dispatch patterns consistent with seasonal operation and reduces hydrogen consumption relative to a rule-based strategy under uncertainty while requiring millisecond-level inference time. Dynamic programming achieved slightly lower hydrogen consumption but incurred orders-of-magnitude higher computation time. Overall, TD3 provides a practical trade-off between near-optimal performance, robustness, and real-time applicability for PEMFC-based building CCHP scheduling. Full article

The use of renewable energy sources instead of conventional ones, together with the development of efficient electricity storage solutions, represents a central objective of the transition to sustainable and resilient energy systems. In this context, two main development directions are the integration of hydrogen in the energy chain (Power-to-Gas) and the use of batteries, each with specific advantages and disadvantages, compared to internal combustion engines. The purpose of this work was to evaluate the dynamic response time of a hydrogen fuel cell model powered by green hydrogen, under conditions of sudden and instantaneous power demand, for its integration into wind-based renewable energy systems. Experimental research was carried out on an autonomous installation designed to operate continuously for an unlimited duration, simulating the integration of hydrogen produced from wind sources. The novelty consists of the application of an instrumental method for automatic measurement of the response time of a proton exchange membrane hydrogen fuel cell, based on the automatic acquisition and processing of measured electrical signals. The response time of the fuel cell was compared with that of an internal combustion engine based on the classic Carnot cycle, using a dedicated oscilloscope. The load connection time, the current and voltage variation as a function of time were recorded simultaneously. The results show that the response time of the fuel cell is relatively short (approximately 0.3 ms), much lower than that of the internal combustion engine (0.7 s), being of the order of about 2333 times smaller. In conclusion, the hydrogen fuel cell can be effectively integrated into renewable energy systems for the role of an uninterruptible power supply, with an exceptionally fast dynamic response, suitable for applications in regulating and supporting wind-powered networks. Full article

Hydrogen is a clean energy carrier with broad application potential. This study focuses on improving hydrogen production efficiency in a proton exchange membrane (PEM) electrolyzer system that integrates a photovoltaic (PV) array, a battery energy storage system, and the electrolyzer. The PV array is interfaced with the electrolyzer through a buck converter using a maximum power point tracking (MPPT) algorithm to ensure maximum energy harvesting. A key contribution of this work is the integration of a battery system through a dual-active-bridge (DAB) converter. The DAB converter employs a multilayer perceptron (MLP) model to dynamically regulate the electrolyzer current and maintain optimal operating efficiency. An adaptive energy management strategy is further proposed to address solar irradiance fluctuations and enhance long-term operational stability. The MLP model is developed in Python and embedded into a PLECS simulation environment. The simulation results verify the effectiveness of the proposed control approach and efficiency optimization scheme. Throughout the simulation period, the PEM electrolyzer sustains an optimal efficiency of 69.9% under maximum PV power output. A limitation of this study is that the efficiency model is derived from the literature and does not yet consider all operational factors, indicating the need for refinement in future work. Full article

To meet aviation decarbonization goals, novel electric energy storage systems are required. A promising approach combines a Li-ion battery with a hydrogen proton exchange membrane fuel cell system (PEMFCS) into an electrochemical energy storage and conversion (EC-ESC) system. Proper power management ensures efficiency, reliability and durability. The study investigates EC-ESC performance for regional hybrid electric aircraft under varying degrees of hybridization. By systematically adjusting the power split between the battery and FCS, we quantify its impacts on system sizing, energy efficiency and battery degradation. The results show that a well-balanced power distribution enhances overall efficiency and energy density while extending system lifetime. Full article

Perfluorosulfonic acid (PFSA) membranes, exemplified by Nafion, suffer dehydration-induced degradation at elevated temperatures, although modifications enhance their conductivity and performance. Sulfonated aromatic polymers (SAPs) exhibit weaker phase separation, yielding narrow, tortuous ion channels and lower conductivity than their PFSA membrane counterparts at equivalent ion exchange capacity; however, excessive sulfonation causes swelling and mechanical instability, offset by cost advantages. Phosphoric acid-doped polybenzimidazole (PBI) offers superior thermal stability and high conductivity, with recent advances in polybenzimidazole derivatives and composites driving medium-to-high temperature proton-exchange membrane fuel cell innovation. This review summarizes progress in three major medium-to-high temperature proton-exchange membrane fuel cell categories—perfluorosulfonic acid, sulfonated polymers, and PBI-based membranes—while addressing challenges and future goals for enhanced performance. Full article

Redox-flow batteries are a promising emerging technology for large-scale storage of renewable energy. However, existing ion-exchange membranes used for separating electrolytes are expensive and often ineffective at preventing crossover of redox-active species, leading to a decrease in battery capacity over time. Herein, we introduce a new class of proton-conducting membranes formed by depositing highly alkylated waxy hydrophobic salts on porous polypropylene supports and demonstrate that they form self-assembled nanostructures which exclusively conduct protons via a unique mechanism of action. These new “ionowax” membranes display comparable proton conductivities to existing commercially available functionalized porous polymer membranes but are cheaper and easier to fabricate. We anticipate that these new membranes will facilitate future development of cheaper and/or longer-lasting aqueous redox-flow batteries. Full article

This study presents an optimized and comparative investigation of four intelligent energy management strategies—Proportional–Integral–Derivative (PID), Fuzzy Logic Control (FLC), Equivalent Consumption Minimization Strategy (ECMS), and Artificial Neural Network (ANN)—applied to a photovoltaic–fuel cell–battery hybrid electric vehicle (PV–FC–HEV). A high-fidelity MATLAB/Simulink model integrates a 6 kW proton-exchange membrane fuel cell (PEMFC), a 500 W photovoltaic subsystem with MPPT, and a lithium-ion battery (LiB) pack. While 1000 W/m² represents Standard Test Conditions (STC), the level of 400 W/m² was specifically selected to simulate average cloudy conditions common in urban driving environments, rather than standard NOCT (800 W/m²), to test the EMS’s robustness under significantly reduced PV support and stressed battery conditions (initial SOC = 30%). While surface contamination and the resulting performance degradation significantly impact real-world results, this study assumes a clean surface to establish an idealized performance baseline for the control algorithms. However, the authors acknowledge that contaminant accumulation is a key factor; future work will incorporate a degradation factor (e.g., a 10–15% efficiency penalty) to evaluate the reliability of these EMS strategies under actual operating conditions. ECMS achieved the lowest hydrogen consumption, saving up to 10 L compared with PID, while ANN maintained the most stable state of charge (SOC > 80%), minimizing deep discharge cycles and improving operational stability. FLC provided balanced operation under fluctuating irradiance. Overall, ANN offered the most harmonized energy flow and dynamic stability, whereas ECMS maximized fuel economy. The findings provide practical guidance for designing sustainable and intelligent control systems in next-generation hybrid electric vehicles. Full article

High-temperature proton exchange membrane fuel cells (HT-PEMFCs) coupled with methanol reforming hold promise for distributed energy systems, yet channel hydrodynamics and geometry optimization remain underexplored. This study develops a 3D multiphysics model to investigate coupled behaviors in HT-PEMFCs fueled by methanol reformate. Results reveal bifurcation-induced Dean vortices have dual effects: they cause flow maldistribution (15–18% velocity deviation) and contribute 50% of inlet pressure loss, while generating a lateral pumping effect that enhances local mass transfer. A continuous parametric sweep of channel widths (0.9–1.9 mm) identifies a voltage-dependent performance crossover—narrower channels (1.3 mm) excel at high voltages by improving electronic conduction, whereas wider channels (1.5 mm) perform better at low voltages by mitigating mass transfer limitations. These findings provide quantitative design criteria for optimizing flow field geometry in HT-PEMFC stacks. Full article