Search Results (148)

In recent years, green hydrogen production via water electrolysis driven by renewable energy sources has garnered increasingly significant attention. Among the various water electrolysis technologies, proton-exchange membrane water electrolysis (PEMWE) distinguishes itself owing to the unique advantages, including the compact architecture, high efficiency, rapid dynamic response, and high purity of the generated hydrogen. The membrane electrode assembly (MEA) serves as the core component of a PEM electrolyzer. And only a high-performance and stable MEA can provide a reliable platform for investigating the mass transport behavior within the porous transport layer (PTL). In this study, the MEA fabrication method was optimized by varying the ionomer-to-carbon (I/C) ratio, coating strategy, and anode Ir mass loading. As a result, the cell voltage was reduced from 1.679 V to 1.645 V at 1.0 A cm⁻², with a small degradation of 1.3% over 70 h of operation. Based on the optimized MEA, the effects of the structure and porosity of PTL on the mass transport behavior were further analyzed. After the PTL parameter optimization, the cell voltage was further reduced to 1.630 V at 1.0 A cm⁻², while a high-speed camera captured bubble dynamics in real time, showing the fast detachment of small oxygen bubbles. The integrated electrochemical and visualization results provide a useful guideline to designing both MEA and PTL for efficient PEMWE. Full article

Green hydrogen production using membrane electrode assembly (MEA) has attracted significant attention due to its remarkable energy conversion efficiency. To further enhance its sustainability, MEA-based water electrolysis can be integrated with renewable solar energy by adopting a photocatalytic MEA (P-MEA) system, incorporating light-transmitting windows into MEA stacks, and employing suitable photocatalytic electrode materials. A critical challenge lies in developing cost-effective and high-performance photocatalytic electrode materials by replacing conventional noble material systems with earth-abundant photocatalytic electrode materials. This review discusses recent advances in P-MEA concepts and fabrication strategies for photoelectrodes tailored to MEA operation. Particular emphasis is placed on elucidating the mechanisms of light-induced charge dynamics that govern the P-MEA-based water electrolysis process. Overall, this review highlights the synergistic potential of integrating photocatalysis with MEA-based water electrolysis to advance sustainable green hydrogen production. Full article

The high efficiency, light weight, and reliability of hydrogen energy electrochemical equipment are among the future development directions. Membrane electrode assemblies (MEAs) and electrolyzers, as key components, have structures and strengths that determine the efficiency of their power generation and the hydrogen production efficiency of electrolyzers. This article summarizes the evolution of membrane electrode and electrolyzer structures, and their power and efficiency in recent years, highlighting the significant role of integrated structures in promoting proton transport and enhancing performance. Finally, it proposes the development direction of integrating electrolyte and electrode manufacturing using phase-change methods. Full article

This study examines the effects of several commercial surfactants on the dispersion of catalyst inks for proton exchange membrane fuel cells (PEMFCs). Catalyst inks containing Pt/C were spray-coated and assembled into membrane electrode assemblies (MEAs) by hot pressing. The structural and electrochemical properties of the resulting catalyst layers were characterized through particle size analysis, zeta potential measurements, contact angle determinations, and single-cell performance tests. Among the formulations evaluated, the ink with non-ionic surfactant Triton X-100 (TX) delivered the best performance, achieving a current density of 1134 mA/cm² at 0.3 V—substantially higher than that of the surfactant-free control. These findings provide practical guidance for selecting appropriate surfactants to optimize catalyst-ink preparation and enhance PEMFC performance. Full article

The advancement of catalytic materials is critical to improving the performance, reducing the cost and enhancing the sustainability of Proton Exchange Membrane (PEM) fuel cells and electrolyzers. Although Platinum Group Metal (PGM)-based electrocatalysts exhibit high electrochemical activity, their limited availability and the environmentally intensive extraction pose significant challenges. This study aims to demonstrate the direct reuse of recycled impure platinum (Pt) precursors for the synthesis of effective Pt/C electrocatalysts as a viable step toward circular hydrogen economy implementation. A low-cost and eco-friendly chlorine-based hydrometallurgical method was successfully employed to recycle over 99% of Pt from End-of-Life (EoL) Membrane Electrode Assemblies (MEAs), with an industrial perspective. Recycled metal precursor was used without purification to synthesize Pt/C electrocatalyst via a scalable and sustainable method. The catalyst was structurally and chemically characterized, and their electrochemical performance towards the Oxygen Reduction Reaction (ORR) was conducted under conditions simulating real operating environments. The recycled-metal-derived catalyst demonstrated comparable activity toward ORR (170 A/gPt) relative to a commercial catalyst, indicating its potential as viable alternative to conventional PGM-based catalysts. By integrating energy-efficient recycling with advanced material design, this work supports the development of cost-effective and green solutions for clean energy technologies aligned with a circular hydrogen economy model. Full article

Fuel cells, as one of the most promising alternatives to lithium-ion batteries for portable power systems, still face significant challenges. A critical issue is their substantial performance degradation under low-humidity conditions. To address this, researchers commonly add silica to components. This study employs a control variable method to systematically investigate the impact of four parameters—gas stoichiometry, temperature, humidity, and silica content—on fuel cell performance. Initially, the effects of gas stoichiometry, temperature, and humidity on performance were examined. Subsequently, hydrophilic silica was incorporated into the membrane electrode assembly (MEA) to assess its potential for improving performance in low-humidity environments. Experimental results reveal that under 100% humidification, silica addition had a minimal impact on performance, particularly at high temperatures where performance improved by only 2.5%. This is attributed to increased water production at elevated temperatures, which—when combined with silica’s water retention properties—exacerbates flooding. However, when humidity was reduced to 50%, silica incorporation significantly enhanced performance. At high temperatures, silica addition resulted in a 126.2% performance improvement, demonstrating its efficacy as a rational strategy under low-humidity conditions. Full article

Nanostructured bimetallic IrSn composites deposited on the natural aluminosilicate montmorillonite were synthesized and evaluated as anode electrocatalysts for polymer electrolyte membrane electrolysis cells (PEMECs). The test series prepared via the sol–gel method consisted of samples with 30 wt. % total metal content and varying Ir:Sn ratio. The performed X-ray diffraction analysis and high-resolution transmission electron icroscopy registered very fine nanostructure of the composites with metal particles size of 2–3 nm homogeneously dispersed on the support surface and also intercalated in the basal space of its layered structure. The electrochemical behavior was investigated by cyclic voltammetry and steady-state polarization techniques. The initial screening was performed in 0.5 M H₂SO₄. Then, the catalysts were integrated as anodes in membrane electrode assemblies (MEAs) and tested in a custom-made PEMEC. The electrochemical tests revealed that the catalysts with Ir:Sn ratio 15:15 and 18:12 wt. % demonstrated high efficiency toward the oxygen evolution reaction during repetitive potential cycling and sustainable performance with current density in the range 140–120 mA cm⁻² at 1.6 V vs. RHE during long-term stability tests. The results obtained give credence to the studied IrSn/MMT nanocomposites to be considered promising, cost-efficient catalysts for the oxygen evolution reaction (OER). Full article

In this study, platinum (Pt) nanocatalysts were synthesized via a sol-gel method over the non-stoichiometric, Magnéli phase titanium oxides (TinO_2n−1) at varying Pt loadings (10–40 wt.%). Their structural and morphological properties were characterized, and after preliminary electrochemical screening, the catalysts were integrated into commercially available gas diffusion electrodes (GDEs) with a three-layer structure to enhance mass transport and catalyst utilization. Membrane electrode assemblies (MEAs) were fabricated using a Nafion^® 117 polymer membrane and tested in a laboratory PEM cell under controlled conditions. The electrochemical activity toward the hydrogen reduction reaction (HRR) was evaluated at room temperature and at elevated temperatures to determine the catalytic efficiency and stability. The optimal Pt loading was determined to be 30 wt.%, achieving a current density of approximately 0.12 A cm⁻² at 0.25 V, demonstrating a balance between catalyst efficiency and material utilization. The chronoamperometry tests showed minimal degradation over prolonged operation, suggesting that the catalysts were durable. These findings highlight the potential of Pt-based catalysts supported on Magnéli phase titanium oxides (TinO_2n−1) for efficient HRRs in electrochemical hydrogen pumps/compressors, offering a promising approach for improving hydrogen compression efficiency and advancing sustainable energy technologies. Full article

The proton exchange membrane water electrolysis (PEMWE) technology is a highly promising method for hydrogen production. The flow field structure is a key factor affecting the electrolyzer’s performance and overall cost. The commonly used flow field designs are typically parallel flow fields or serpentine flow fields. However, parallel flow fields often suffer from an uneven distribution of reactants, which can negatively impact electrolyzer performance. Serpentine flow fields, on the other hand, exhibit higher pressure drops, leading to increased energy consumption. Furthermore, research on circular planar flow field designs in PEMWE has been limited. Therefore, this study proposes a novel annular flow field design based on a circular plane using Murray’s branching law, with comparative analysis against parallel and serpentine flow fields. This design aims to address the aforementioned issues. A three-dimensional numerical model coupling multiple physical fields was developed with the aim of verifying the effectiveness of the annular flow field design in terms of pressure drop, velocity distribution, temperature distribution, hydrogen distribution, and polarization curves. To confirm the model’s reliability, bipolar plates with the novel annular flow field were fabricated and assembled into a single cell for validation. The results show that the novel annular flow field exhibits optimal electrolytic performance and can significantly improve the uniformity of flow and temperature distribution in PEMWE. At a voltage of 2.6 V, the current density increased by 29.99% and 13.84% compared to the parallel and serpentine flow fields, respectively. The velocity distribution was the most uniform, and the average temperature of the Membrane Electrode Assembly (MEA) decreased by approximately 6.08 K and 6.84 K compared to the parallel and serpentine flow fields, respectively. Notably, the pressure drop of the annular flow field was significantly reduced, with reductions of 53.63% and 46.09% compared to the parallel and serpentine flow fields, respectively. This study provides an effective solution for the design of circular plane flow fields in PEMWE. Full article

This study presents the integration and evaluation of commercially available gas diffusion electrodes (GDEs), specifically designed for high-temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) within membrane electrode assemblies (MEA) for electrochemical hydrogen pump/compressor applications (EHP/C). Using Nafion 117 as a solid polymer electrolyte, the MEAs were analyzed for cell efficiency, hydrogen evolution, and hydrogen oxidation reactions (HER and HOR) under differential pressure up to 16 bar and a temperature ranging from 20 °C to 60 °C. Key properties of the GDEs, such as electrode thickness and conductivity, were investigated. The catalytic layer was characterized via XRD and EDX analyses to assess its surface and bulk composition. Additionally, the effects of increasing MEA’s geometric size (from 1 cm² to 5 cm²) and hydrogen crossover phenomena on the efficiency were examined in a single-cell setup. Electrochemical performance tests conducted in a single electrochemical hydrogen pump/compressor cell under hydrogen flow rates from 36.6 Ml·min⁻¹·cm⁻² to 51.3 mL·min⁻¹ cm⁻² at atmospheric pressure provided insights into the optimal operational parameters. For a double-stage application, the MEAs demonstrated enhanced current densities, achieving up to 0.6 A·cm⁻² at room temperature with further increases to 1 A·cm⁻² at elevated temperatures. These results corroborated the single-cell data, highlighting potential improvements in system efficiency and a reduction in adverse effects. The work underscores the potential of HT-PEMFC-based GDEs for the integration of MEAs applicable to advanced hydrogen compression technologies. Full article

Hydrogen leakage in Proton Exchange Membrane (PEM) fuel cells poses critical safety, efficiency, and operational reliability risks. This study introduces an innovative infrared (IR) thermography-based methodology for detecting and quantifying hydrogen leaks towards the outside of PEM fuel cells. The proposed method leverages the catalytic properties of a membrane electrode assembly (MEA) as an active thermal tracer, facilitating real-time visualisation and assessment of hydrogen leaks. Experimental tests were conducted on a single-cell PEM fuel cell equipped with intact and defective gaskets to evaluate the method’s effectiveness. Results indicate that the active tracer generates distinct thermal signatures proportional to the leakage rate, overcoming the limitations of hydrogen’s low IR emissivity. Comparative analysis with passive tracers and baseline configurations highlights the active tracer-based approach’s superior positional accuracy and sensitivity. Additionally, the method aligns detected thermal anomalies with defect locations, validated through pressure distribution maps. This novel, non-invasive technique offers precise, reliable, and scalable solutions for hydrogen leak detection, making it suitable for dynamic operational environments and industrial applications. The findings significantly advance hydrogen’s safety diagnostics, supporting the broader adoption of hydrogen-based energy systems. Full article

The electrochemical reduction from nitrate (NO₃RR) to ammonia (NH₃) provides a decentralized and environmentally friendly route for sustainable ammonia production while addressing the urgent issue of nitrate pollution in water bodies. Recent advancements in NO₃RR research have improved catalyst designs, mechanistic understanding, and electrolyzer technologies, enhancing selectivity, yield, and energy efficiency. This review explores cutting-edge developments, focusing on innovative designs for catalysts and electrolyzers, such as membrane electrode assemblies (MEA) and electrolyzer configurations, understanding the role of membranes in MEA designs, and various types of hybrid and membrane-free reactors. Furthermore, the integration of NO₃RR with anodic oxidation reactions has been demonstrated to improve overall efficiency by generating valuable co-products. However, challenges such as competitive hydrogen evolution, catalyst degradation, and scalability remain critical barriers to large-scale adoption. We provide a comprehensive overview of recent progress, evaluate current limitations, and identify future research directions for realizing the full potential of NO₃RR in sustainable nitrogen cycling and ammonia synthesis. Full article

In this study, mono- and bimetallic platinum (Pt), palladium (Pd) and Pt-Pd nanoparticles were synthesized using the wet sol–gel method, employing a carbon-based XC72R as catalytic carrier. The overall metal content was set at 40 wt.% at varying Pt:Pd ratios. Characterization of the morphology and surface structure was conducted through scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Brunauer–Emmett–Teller (BET) and X-ray diffraction (XRD) analyses. The electrochemical performance and catalytic activity against the hydrogen evolution reaction (HER) were assessed in a three-electrode cell for screening purposes, as well as in a prototype cell of an electrochemical hydrogen pump/compressor (EHP/C) where the catalysts served as cathodes, while the anode was Pt/XC72 40% wt. with 0.38 mg_Pt·cm⁻² within a membrane electrode assembly (MEA) with a 180 µm thick Nafion 117 proton-conductive membrane. The results obtained indicated superior catalytic activity of the bimetallic catalysts in comparison to the pure metal samples. Further electrochemical tests in an EHP/C cell at varying differential pressures in the range of 0–3 bar revealed stable behavior and high current density, reaching approximately 0.7 A cm⁻² at 60 °C. The accelerated durability tests performed demonstrated excellent stability of the synthesized composite catalysts. These findings underscore the potential of Pt-Pd nanoparticles as efficient catalysts with sustainable performance for electrochemical hydrogen pumping/compressing applications. Full article

Proton Exchange Membrane Fuel Cells (PEMFCs) are widely regarded as promising clean energy technologies due to their high energy conversion efficiency, low environmental impact, and versatile application potential in transportation, stationary power, and portable devices. Central to the operation and performance of PEMFCs are advancements in materials and manufacturing processes that directly influence their efficiency, durability, and scalability. This review provides a comprehensive overview of recent progress in these areas, emphasizing the critical role of membrane electrode assembly (MEA) technology and its constituent components, including catalyst layers, membranes, and gas diffusion layers (GDLs). The MEA, as the heart of PEMFCs, has seen significant innovations in its structure and manufacturing methodologies to ensure optimal performance and durability. At the material level, catalyst layer advancements, including the development of platinum-group metal catalysts and cost-effective non-precious alternatives, have focused on improving catalytic activity, durability, and mass transport. Similarly, the evolution of membranes, particularly advancements in perfluorosulfonic acid membranes and alternative hydrocarbon-based or composite materials, has addressed challenges related to proton conductivity, mechanical stability, and operation under harsh conditions such as low humidity or high temperature. Additionally, innovations in gas diffusion layers have optimized their porosity, hydrophobicity, and structural properties, ensuring efficient reactant and product transport within the cell. By examining these interrelated aspects of PEMFC development, this review aims to provide a holistic understanding of the state of the art in PEMFC materials and manufacturing technologies, offering insights for future research and the practical implementation of high-performance fuel cells. Full article

Recently, the recovery of metals extracted from the spent membrane electrode assemblies (MEAs) of fuel cells has attracted significant scientific attention due to its detrimental environmental impacts. Two major approaches, i.e., pyrometallurgical and hydrometallurgical, have been explored to recover platinum group metals (PMGs) from used proton exchange membrane fuel cells (PEMFCs). However, the efficacy of these methods has been limited by the low concentrations of the metals and the high costs involved. Essentially, pyrometallurgical processes result in the evolution of harmful gases. Thus, the hydrometallurgical process is preferred as a suitable alternative. In this review, an overview of the application of pyrometallurgical and hydrometallurgical methods in the recovery of PGMs is presented. The health risks, benefits, and limitations of these processes are highlighted. Finally, the hurdles faced by, opportunities for, and future directions of these approaches are identified. It is envisaged that this review will shed light on the current status of processes for the recovery of spent PGMs and propel their advancement for effective recycling strategies. Full article