A review of research progress in mass transfer enhancement of water electrolyzer for hydrogen production

Under the background of the global “double carbon” goal and the intermittent problem of renewable energy, water electrolysis for hydrogen production is a key technology bridging renewable energy and various end-use applications. Its mass transfer efficiency directly affects the performance and economy of hydrogen production. Unlike previous reviews that often focus on a single technology, this review systematically compares mass transport enhancement across three mainstream technologies: Alkaline Water Electrolysis (AWE), Proton Exchange Membrane Water Electrolysis (PEMWE), and Anion Exchange Membrane Water Electrolysis (AEMWE). A key novelty of this review lies in its cross-technology comparative analysis, which clarifies the gas–liquid transport mechanisms, mass transfer characteristics in key components, and distinct bottlenecks of each electrolysis system. This cross-technology comparison establishes a unique framework for identifying common bottlenecks and technology-specific optimization strategies. In addition, this review places special emphasis on scale-up-related mass transfer challenges that are often overlooked in the literature, including uneven mass distribution, current shunt, and thermal management issues. Design optimizations of typical flow field configurations and emerging mass transfer enhancement strategies are also summarized. Finally, the paper outlines future development trends for efficient, low-cost, and large-scale green hydrogen production technology. This review aims to provide a theoretical foundation and technical reference for the optimization of mass transport and system design in water electrolysis for hydrogen production.