A comprehensive review of the state-of-the-art of proton exchange membrane water electrolysis

Hydrogen has attracted growing research interest due to its exceptionally high energy per mass content and being a clean energy carrier, unlike the widely used hydrocarbon fuels. With the possibility of long-term energy storage and re-electrification, hydrogen promises to promote the effective utilization of renewable and sustainable energy resources. Clean hydrogen can be produced through a renewable-powered water electrolysis process. Although alkaline water electrolysis is currently the mature and commercially available electrolysis technology for hydrogen production, it has several shortcomings that hinder its integration with intermittent and fluctuating renewable energy sources. The proton exchange membrane water electrolysis (PEMWE) technology has been developed to offer high voltage efficiencies at high current densities. Besides, PEMWE cells are characterized by a fast system response to fluctuating renewable power, enabling operations at broader partial power load ranges while consistently delivering high-purity hydrogen with low ohmic losses. Recently, much effort has been devoted to improving the efficiency, performance, durability, and economy of PEMWE cells. The research activities in this context include investigations of different cell component materials, protective coatings, and material characterizations, as well as the synthesis and analysis of new electrocatalysts for enhanced electrochemical activity and stability with minimized use of noble metals. Further, many modeling studies have been reported to analyze cell performance considering cell electrochemistry, overvoltage, and thermodynamics. Thus, it is imperative to review and compile recent research studies covering multiple aspects of PEMWE cells in one literature to present advancements and limitations of this field. This article offers a comprehensive review of the state-of-the-art of PEMWE cells. It compiles recent research on each PEMWE cell component and discusses how the characteristics of these components affect the overall cell performance. In addition, the electrochemical activity and stability of various catalyst materials are reviewed. Further, the thermodynamics and electrochemistry of electrolytic water splitting are described, and inherent cell overvoltage are elucidated. The available literature on PEMWE cell modeling, aimed at analyzing the performance of PEMWE cells, is compiled. Overall, this article provides the advancements in cell components, materials, electrocatalysts, and modeling research for PEMWE to promote the effective utilization of renewable but intermittent and fluctuating energy in the pursuit of a seamless transition to clean energy.