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/Mo₂ C 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 Mo₂ C through the formed "Co─C─Mo" bond at the interface of CoO/Mo₂ C, 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/Mo₂ C 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/Mo₂ C 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.