Progress in porous transport layer for hydrogen production via proton exchange membrane water electrolysis

Hydrogen energy, as one of the cleanest energy sources, has emerged as a leading candidate for replacing nonrenewable energy. However, hydrogen is not directly available from nature. Challenges such as high production costs and the need for efficient large-scale production technologies remain significant obstacles. Among the various hydrogen production methods, water electrolysis stands out due to its environmentally friendly nature and the high purity of hydrogen produced. Proton exchange membrane (PEM) electrolyzers are promising devices for hydrogen production. They exhibit the superiorities in high operational current densities exceeding 2 A cm⁻², greater resistance to fluctuations, and improved electrolysis efficiency. A critical component of PEM water electrolyzers is the porous transport layer (PTL), which serves as an electron conductor between the membrane electrode assembly and the bipolar plate, ensuring efficient mass transport between gas and liquid phases. This review provides a comprehensive examination of PTL materials, structural configurations, surface treatments, and the resulting performance of electrolytic cells. These insights aim to guide researchers in selecting appropriate PTL materials and treatments tailored to specific practical applications. Additionally, this paper analyzes operational conditions—such as compaction pressure, temperature, water flow rate, and oxygen saturation within the electrolyzer—that influence PTL performance. These factors are crucial for researchers to holistically design and optimize PEM electrolyzer systems.

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