Conversion of Layered WS2 Crystals into Mixed‐Domain Electrochemical Catalysts by Plasma‐Assisted Surface Reconstruction

Abstract

AbstractElectrocatalytic water splitting is crucial to generate clean hydrogen fuel, but implementation at an industrial scale remains limited due to dependence on expensive platinum (Pt)‐based electrocatalysts. Here, an all‐dry process to transform electrochemically inert bulk WS2 into a multidomain electrochemical catalyst that enables scalable and cost‐effective implementation of the hydrogen evolution reaction (HER) in water electrolysis is reported. Direct dry transfer of WS2 flakes to a gold thin film deposited on a silicon substrate provides a general platform to produce the working electrodes for HER with tunable charge transfer resistance. By treating the mechanically exfoliated WS2 with sequential Ar‐O2 plasma, mixed domains of WS2, WO3, and tungsten oxysulfide form on the surfaces of the flakes, which gives rise to a superior HER with much greater long‐term stability and steady‐state activity compared to Pt. Using density functional theory, ultraefficient atomic sites formed on the constituent nanodomains are identified, and the quantification of atomic‐scale reactivities and resulting HER activities fully support the experimental observations.