Customized Electronic Modulations of Transition Metal Chalcogenide Electrodes Via Heterointerfacing/High‐Valence Doping Toward High‐Performance Water Electrolysis with Ampere‐Level Current Density

Abstract Electrochemical water splitting offers an advancing approach to producing highly pure hydrogen and oxygen, motivated by the prevalence of a low‐carbon economy and the goal of a sustainable future. The customized modulation of electronic structures enables the electrocatalyst to directionally promote hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), which is a promising shortcut to overall water splitting (OWS). Herein, 3D homologous WSeS/CoSeS heterojunction nanoarrays (WSeS/CoSeS NAs) and W‐doped CoSeS nanoarrays (W‐CoSeS NAs) are investigated. Abundant heterointerfaces within WSeS/CoSeS NAs facilitate HER kinetics, boosting mass diffusivity, and increasing carrier separation and transfer process. High‐valence W6+ doping into CoSeS prevents phase separation and stabilizes Co sites by charge offset effect, leading to enhanced OER. Consequently, the WSeS/CoSe…