Interfacial engineering of ZIF-67 derived CoSe/Co(OH)2 catalysts for efficient overall water splitting

Electrocatalytic water splitting is emerged as a clean method for preparing hydrogen for green fuel development. High-efficient electrocatalysts with robust activity and desirable stability are urgent required. Herein, CoSe/Co(OH)2 carbonous material (CoSe/Co(OH)2-CM (AE)) is constructed via acid etching and in-situ selenization method. Acid etching was employed to expose more Co atoms to increase the active sites and facilitate the selenization process. CoSe/Co(OH)2 carbonous nanoparticles with optimized composition and morphology advantages manifest accelerated catalytic activity. The characterization results combined with theory calculations reveal that the nanointerface interaction between Co(OH)2 and CoSe modifies the electronic structure of Co atoms, thus increasing the intrinsic activity of active sites. The CoSe/Co(OH)2-CM (AE) exhibits superior electrocatalytic performance with a low overpotential of 299 mV for OER and 207 mV for HER at 10 mA cm−2 in 1.0 M KOH electrolyte, respectively. Moreover, the CoSe/Co(OH)2-CM (AE) served as both the cathode and anode only needs a potential of 1.65 V to achieve 10 mA cm−2 for overall water splitting. This work puts forward an in-situ route to construct transition-metal based electrocatalysts with modulated electronic structure towards highly efficient water splitting.