Multiscale engineering of anode catalyst layers in proton exchange membrane water electrolyzers

Proton exchange membrane water electrolyzers (PEMWEs) play a key role in promoting the development of the clean hydrogen energy industry and accelerating the achievement of carbon neutrality goals due to their advantages of high efficiency, low energy consumption, ease of integration and fast response. In PEMWEs, the water oxidation reaction in the anode catalytic layer is the core process, and its catalytic efficiency directly determines the performance and stability of the electrolyzers. Therefore, enhancement of reactant transport, electron/proton transfer, and oxygen release by cross-scale optimisation of the anode catalytic layer is crucial for improving the efficiency of PEMWEs. This article highlights recent advances in optimizing the anode catalytic layer of PEMWEs through multi-scale engineering strategies. We first introduce the basic structure of PEMWEs and the importance of the anode catalyst. Subsequently, we discuss in detail the multiscale optimisation strategy of the anode catalyst layer, including the design of active sites at the atomic scale, the morphology regulation at the nano/micro scale, the catalytic layer optimization at the macroscopic scale and the comprehensive synergistic effect of multiscale engineering. Finally, we conclude and look forward to the existing challenges and future research directions for optimising anode catalyst layers by multiscale engineering.