Atomic-level insight into engineering interfacial hydrogen microenvironments of metal-based catalysts for alkaline hydrogen electrocatalysis

Abstract

Alkaline hydrogen oxidation reaction (HOR) and hydrogen evolution reaction (HER) are cornerstones for hydrogen utilization in anion exchange membrane fuel cells (AEMFCs) and hydrogen production in anion exchange membrane water electrolyzers (AEMWEs), respectively, with the advantages of using economic catalysts. Nevertheless, even with state-of-the-art Pt, the reaction kinetics of HOR/HER in base are still two orders of magnitude lower than those in acidic systems. For these heterogeneous electrocatalytic processes, the interfacial hydrogen microenvironments have been recently found to be pivotal to the reaction kinetics. Accordingly, it is highly attractive to develop high-performance catalysts with well-unveiled interfacial hydrogen microenvironments towards alkaline HOR/HER. Here, the interfacial hydrogen microenvironments in alkaline HOR/HER are briefly elucidated as a prerequisite for developing catalysts. Meanwhile, the roles of atomic arrangement asymmetry, atomic stacking configuration and atomic boundary structure of metal-based catalysts in tailoring the interfacial hydrogen delivery, interfacial hydrogen accumulation and interfacial hydrogen spillover during alkaline HOR/HER are discussed, respectively. Subsequently, feasible synthesis strategies of metal-based catalysts to achieve confined interfacial hydrogen microenvironments are presented. Furthermore, major challenges and promising directions for designing efficient catalysts with well-engineered interfacial hydrogen microenvironments towards alkaline HOR/HER are highlighted for future studies.