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

Abstract

Alkaline hydrogen oxidation reaction (HOR) and hydrogen evolution reaction (HER) are the cornerstones of hydrogen utilization in anion exchange membrane fuel cells (AEMFCs) and hydrogen production in anion exchange membrane water electrolyzers (AEMWEs), respectively, with the advantage of using economic catalysts. Nevertheless, even with the state-of-the-art Pt catalyst, the reaction kinetics of HOR/HER in basic media are still two orders of magnitude lower than those in acidic systems. In these heterogeneous electrocatalytic processes, the interfacial hydrogen microenvironment is pivotal to the reaction kinetics. Accordingly, it is highly desired to develop high-performance catalysts with well-regulated interfacial hydrogen microenvironments for alkaline HOR/HER. Herein, the interfacial hydrogen microenvironments in alkaline HOR/HER are briefly elucidated as prerequisites for developing efficient 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, respectively, during alkaline HOR/HER are discussed. Subsequently, feasible synthesis strategies for 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 for alkaline HOR/HER are highlighted for future studies.