Crystal phase dependent solar driven hydrogen evolution catalysis over cobalt diselenide

Abstract

The design of robust metallic transition metal dichalcogenides (TMDs)-based materials for photocatalytic water splitting is desirable but challenging. Here we report the exploration and crystal phase engineering of metallic CoSe2 as cocatalysts for photocatalytic hydrogen evolution. The potential of orthorhombic and cubic CoSe2 (i.e. o-CoSe2, c-CoSe2) as cocatalysts are evaluated by theoretical simulation. Experimentally, o-CoSe2 and c-CoSe2 are rationally anchored to ultrathin g-C3N4 nanosheets, which provides a platform to evaluate the practical photocatalytic activity. The experimental results reveal the crystal phase dependent hydrogen evolution catalysis, i.e., the hydrogen evolution can be proceeded more efficiently on o-CoSe2 surface compared to c-CoSe2. We demonstrate that o-CoSe2 possesses more favorable hydrogen adsorption capacity and can thus tune the rate-determining step, i.e., the surface conversion from H+ to H2, leading to enhanced performance. The presented results provide insights into the role of phase engineering and a strategy for enhanced catalysis.