Constructing CoO/Mo₂C Heterostructures with Interfacial Electron Redistribution Induced by Work Functions for Boosting Overall Water Splitting

Abstract

Space charge transfer of heterostructures driven by the work‐function‐induced built‐in field can regulate the electronic structure of catalysts and boost the catalytic activity. Herein, an epitaxial heterojunction catalyst of CoO/Mo₂C with interfacial electron redistribution induced by work functions (WFs) is constructed for overall water splitting via a novel top‐down strategy. Theoretical simulations and experimental results unveil that the WFs‐induced built‐in field facilitates the electron transfer from CoO to Mo₂C through the formed “Co─C─Mo” bond at the interface of CoO/Mo₂C, achieving interfacial electron redistribution, further optimizing the Gibbs free energy of primitive reaction step and then accelerating kinetics of hydrogen evolution reaction (HER). As expected, the CoO/Mo₂C with interfacial effects exhibits excellent HER catalytic activity with only needing the overpotential of 107 mV to achieve 10 mA cm⁻² and stability for a 60‐h continuous catalyzing. Besides, the assembled CoO/Mo₂C behaves the outstanding performance toward overall water splitting (1.58 V for 10 mA cm⁻²). This work provides a novel possibility of designing materials based on interfacial effects arising from the built‐in field for application in other fields.