Solar-driven photoelectron injection effect on MgCo2O4@WO3 core–shell heterostructure for efficient overall water splitting

By integrating the light-absorbing semiconductor materials into the electrocatalytic network, using the photogenerated-carrier-driven strategy, and thus permitting solar energy to operate as the extra driving force, the efficiency of electrocatalytic water splitting (EWS) is expected to be improved. However, the rational plot of such integrated catalytic system remains an enormous challenge due to the spatial disparity between photocatalytic components and electrocatalytic components. Herein, a MgCo2O4@WO3 core–shell heterostructure (MCW CSHS) is constructed by the simple one-step hydrothermal coordination of the spinel oxide MgCo2O4 (as the electron acceptor) and the WO3 semiconductor (as the electron donor). The cogitatively designed MCW CSHS catalyst can effectively eliminate the spatial disparity between the two above functional components and provide significantly increased surface area and roughness, which can enhance light absorption by restraining diffuse reflection and promoting electron transfer in EWS. Under solar illumination, the electrocatalytic activity of MCW CSHS is significantly improved due to the electronic structure regulation, yielding 50 mA·cm−2 at overpotentials of 243 mV for oxygen evolution reactions and 161 mV for hydrogen evolution reactions in 1 M KOH. The solar energy enhanced electrochemical system based on bifunctional materials has a broad application prospect in the efficient H2 production by EWS.