Abstract
As an important energy carrier in terms of carbon neutrality, green hydrogen produced by water electrolysis using renewable electricity has attracted worldwide attention. The polymer electrolyte water electrolyzer (PEWE) has the potential to be a mainstay in the green hydrogen market in the future because of its superior performance. However, the development of PEWE is constrained by the slow progress of the membrane electrode assembly (MEA), which is an essential component of PEWE and largely determines the cost and performance of the system. Therefore, the MEA must be optimized from the aspects of reducing cost and improving performance to promote the development of PEWEs. In this review, we first discuss the recent progress of the materials and design strategies of MEA, including the cost, activity, and stability of catalysts, distribution and thickness of ionomers, and ion transport efficiency of ion exchange membranes (IEMs). Then, the effects of all components and interlayer interfaces on the ions, electrons, and mass transfer in MEA and, consequently, the performance of PEWE are analyzed. Finally, we propose perspectives on developing MEA by optimizing the catalyst activity and stability of IEM, interface contact between adjacent components, and evaluation methods of performance.