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Proton exchange membrane fuel cells (PEMFCs) are an attractive type of fuel cell that have received successful commercialization, benefitted from its unique advantages (including an all solid-state structure, a low operating temperature and low environmental impact). In general, the structure of PEMFCs can be regarded as a sequential stacking of functional layers, among which the gas diffusion layer (GDL) plays an important role in connecting bipolar plates and catalyst layers both physically and electrically, offering a route for gas diffusion and drainage and providing mechanical support to the membrane electrode assemblies. The GDL commonly contains two layers; one is a thick and rigid macroporous substrate (MPS) and the other is a thin microporous layer (MPL), both with special functions. This work provides a brief review on the GDL to explain its structure and functions, summarize recent progress and outline future perspectives.

Three-dimensional printing (3DP) is a technology useful for fabricating both structural and energy devices. Of great concern to this review is promising nature of additive manufacturing (AM) for engineering fuel cells (FCs) for clean energy conversion. 3DP technique is useful for the fabrication of fuel cell components, and they offer waste minimization, low-cost, and complex geometric structures. In this review, significance of different 3DP techniques toward revolutionizing fuel cell fabrication is given. The aim is to unravel the importance and status of 3D-printed fuel cells and hence provides researchers and scientists with extensive opportunities of 3DP techniques for fuel cell engineering. After careful selection of state-of-the-art literatures, different kinds of 3DP techniques of relevance to electrolytes, electrodes, and other key components (e.g., gas diffusion layers (GDLs), bipolar plates (BPs), and membrane electrode assembly (MEA)) fabrication are explicitly discussed. Among the techniques, the best approaches are recommended for further studies. Advantages associated with these techniques are indicated for the benefit of those whose interests matter most on clean energy production. The challenges researchers are facing in the use of 3DP for fuel cell fabrications are identified. Possible solutions to the identified challenges are suggested as way forward to further development in this research area. It is expected that this review article will benefit engineers and scientists who have interest on clean energy conversion devices.

In this paper, we report the preparation of a gas diffusion layer (GDL) with different gradient pore size structures. The pore structure of microporous layers (MPL) was controlled by the amount of pore-making agent sodium bicarbonate (NaHCO3). We investigated the effects of the two-stage MPL and the different pore size structures in the two-stage MPL on the performance of proton exchange membrane fuel cells (PEMFC). The conductivity and water contact angle tests showed that the GDL had outstanding conductivity and good hydrophobicity. The results of the pore size distribution test indicated that introducing a pore-making agent altered the pore size distribution of the GDL and increased the capillary pressure difference within the GDL. Specifically, there was an increase in pore size within the 7–20 μm and 20–50 μm ranges, which improved the stability of water and gas transmission within the fuel cell. The maximum power density of the GDL03 was increased by 37.1% at 40% humidity, 38.9% at 60% humidity, and 36.5% at 100% humidity when compared to the commercial GDL29BC in a hydrogen-air environment. The design of gradient MPL ensured that the pore size between carbon paper and MPL changed from an initially abrupt state to a smooth transition state, which significantly improved the water and gas management capabilities of PEMFC.

Hydrogen is considered to be the fuel of the future and with the advancement of fuel cell technology, there is a renewed interest in hydrogen production by the electrolysis of water. Among low-temperature water electrolysis options, polymer electrolyte membrane (PEM) electrolyzer is the preferred choice due to its compact size, intermittent use, and connectivity with renewable energy. In addition, it is possible to generate compressed hydrogen directly in the PEM electrolyzer, thereby reducing the additional pressurization cost for hydrogen storage. The development of electrocatalysts for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is a major focus of electrolysis research. Other components, such as PEMs, gas diffusion layers (GDL), and bipolar plates (BPs) have also received significant attention to enhance the overall efficiency of PEM electrolyzers. Improvements in each component or process of the PEM electrolyzer have a significant impact on increasing the energy efficiency of the electrolyzer. This work discusses various synthesis techniques to improve the dispersion of OER electrocatalyst and reducing catalyst loading for the PEM electrolyzer. Various techniques are discussed for the development of electrocatalysts, including nanostructured, core shell, and electrodeposition to deposit catalysts on GDL. The design and methodology of new and improved GDL are discussed along with the fabrication of gas diffusion electrodes and passivation techniques to reduce the oxidation of GDL. The passivation technique of BPs using Au and Pt is summarized for its effect on electrolysis efficiency. Finally, the optimization of various operating conditions for PEM electrolyzer are reviewed to improve the efficiency of the electrolyzer.

At present, the proton exchange membrane fuel cell (PEMFC) is one of the most promising new energy solutions. The structure and material properties of the gas diffusion layer (GDL) are important factors that restrict the efficient water management and structural stability of PEMFCs. The complex mesoscopic fibrous porous structure of the GDL results in complex multiphase flow dynamics problems that have highly nonlinear characteristics. It is difficult to describe the details of mesoscopic multiphase coupled transport dynamics and numerically solve problems in which there is a two-phase flow with a high-density ratio. To solve these problems, a mesoscopic multiphase coupled transport model based on a lattice Boltzmann method and volume-of-fluid (LBM-VOF) model is proposed. Moreover, we also discuss the mechanism of the interaction between the fibrous porous structure and internal multiphase flow. The results obtained illustrate that the proposed method can obtain dynamic details of the flow field for fibrous porous media. The surface wettability of fibres strongly influences both the distribution and stability of liquid water clusters within porous materials. Concurrently, the fibre diameter assumes a pivotal role in governing lateral water diffusion and exclusion efficiency. This work lays a foundation for efficient water and thermal management of PEMFCs.

The consumption of hydrogen could increase by sixfold in 2050 compared to 2020 levels, reaching about 530 Mt. Against this backdrop, the proton exchange membrane fuel cell (PEMFC) has been a major research area in the field of energy engineering. Several reviews have been provided in the existing corpus of literature on PEMFC, but questions related to their evolutionary nuances and research hotspots remain largely unanswered. To fill this gap, the current review uses bibliometric analysis to analyze PEMFC articles indexed in the Scopus database that were published between 2000–2021. It has been revealed that the research field is growing at an annual average growth rate of 19.35%, with publications from 2016 to 2012 alone making up 46% of the total articles available since 2000. As the two most energy-consuming economies in the world, the contributions made towards the progress of PEMFC research have largely been from China and the US. From the research trend found in this investigation, it is clear that the focus of the researchers in the field has largely been to improve the performance and efficiency of PEMFC and its components, which is evident from dominating keywords or phrases such as ‘oxygen reduction reaction’, ‘electrocatalysis’, ‘proton exchange membrane’, ‘gas diffusion layer’, ‘water management’, ‘polybenzimidazole’, ‘durability’, and ‘bipolar plate’. We anticipate that the provision of the research themes that have emerged in the PEMFC field in the last two decades from the scientific mapping technique will guide existing and prospective researchers in the field going forward.

Gas diffusion layer (GDL) plays a very important role in the proton exchange membrane fuel cell (PEMFC), and changing the GDL structure becomes a good way to improve the PEMFC performance. GDL with different perforation diameters and perforation depths are established by the stochastic reconstruction method. The perforation filling amount is introduced to simulate the reservoir effect of the perforated structure, and the lattice Boltzmann method (LBM) is used to computationally study the gas transport performance within the perforated GDL. The results show the perforated structure can significantly improve the gas transport performance, and the influence on each porosity structure varies when containing different perforated filling amounts. When the porosity is larger, the effective diffusion coefficient of perforated structure is lower than that of non-perforated structure with less filling amount. The calculation of anisotropic permeability reveals that the through-plane permeability is greater than the in-plane permeability when the perforation reaches a certain depth, and the optimal perforation diameter and depth in each structure are analyzed from the perspective of maximizing the average permeability in the through-plane direction. Article highlights The complete structure of the gas diffusion layer was stochastic reconstructed and perforated. The effects of different perforation structures on the gas transport properties were mainly investigated by Lattice Boltzmann method, and the presence of a homogeneous filler inside the perforation was considered. The optimal parameters of different perforated structures and GDL porosity structures were compared and analyzed.

When fabricating high-entropy alloy particle-reinforced metal matrix composites via friction stir processing, the relatively low heat input led to insufficient interfacial diffusion between the particles and matrix, thereby compromising the composite properties. To address this issue, this study introduced an electroless copper plating step followed by heat treatment to produce Cu-coated HEA particles with an interfacial diffusion layer. These modified particles were then incorporated into a copper matrix via friction stir processing to form composites with an intentionally designed interfacial diffusion layer. The results indicate that the diffusion layer structure contributed to excellent interfacial bonding. The resulting composite exhibited a simultaneous enhancement in both strength and ductility. The tensile strength and elongation reached 372.5 MPa and 34.2%, respectively, representing increases of 20.4% and 54% compared to pure copper. The wear rate of the composite reduced by 33.7% relative to pure copper. Quantitative analysis indicated that the contribution of fine-grain strengthening, Orowan strengthening, dislocation strengthening, and load transfer strengthening to the overall strength was 41.2 MPa, 0.3 MPa, 12.7 MPa, and 15.7 MPa, respectively.

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.

X-ray computed tomography (CT) is increasingly used to characterize the morphology of water distribution in gas diffusion layers (GDLs) for polymer electrolyte fuel cell (PEFC) applications. The resulting images can provide access to critical performance data for GDLs, including internal water contact angle distributions, water saturation, water cluster size, and pore-size distributions. Given the propensity for unimodal grayscale pixel distributions in X-ray CT images, basic image processing techniques like thresholding, erosion, and dilation are often insufficient. To address this issue, we used machine learning algorithms to segment X-ray CT image stacks of GDLs, comparing the performance of basic image processing with decision tree learning (via Trainable WEKA Segmentation) and convolutional neural networks (CNNs) (via U-Net and MSDNet). The training methods and classification features for each algorithm were varied and evaluated against a GDL sample with a semi-bimodal pixel distribution (SGL 10BA) and a more difficult, unimodal sample (EP40T). The optimal combinations for each algorithm were then applied to segment a GDL sample with a microporous layer (MPL), an SGL 10BC, as MPL-containing GDLs are generally preferred in PEFCs. We found that decision tree learning, aside from being the easiest to use, exhibited the best performance for each of the four phases—pores, water, GDL, and MPL—based on F 1 scores. Based on the wide collection of literature, properly trained CNNs should produce significantly better results. However, obtaining such results may require substantially more investment to determine the optimal algorithm for a particular scenario.