High Photo-electrochemical and Hydrogen Evolution Reaction Activities from 0D/2D ZnSe/(001)CuSe Heterojunction Catalysts Constructed by ZnSe Nanoparticles and {001} Facets-Exposed CuSe Nanosheets

ZnSe nanoparticles were loaded on {001} facets-exposed CuSe nanosheets to construct a 0D/2D ZnSe/(001)CuSe heterojunction catalyst. This ZnSe/(001)CuSe catalyst exhibits high photoelectrochemical (PEC) and hydrogen evolution reaction (HER) properties. The photocurrent of the heterojunction catalyst displays 600% enhancement, whereas in the HER the heterojunction catalyst shows a Tafel slope as low as 57 mV/dec that decreases 367% compared with CuSe. Hydroxyl has been confirmed to be the active group, which confirms the heterojunction catalyst remains the high valence band (VB) potential of ZnSe. It is considered that the exposed {001} facets of CuSe are crucial. Double heterojunctions are formed between the ZnSe/(001)CuSe: a crystal facets heterojunction between the {101} and {001} facets of CuSe will separate the carriers in CuSe, then a semiconductor heterojunction between ZnSe and CuSe can cause a photoinduced electron flow from the conduction band (CB) of ZnSe to that of CuSe. Most importantly, the photoinduced holes in the VB of ZnSe can hardly flow into that of CuSe due to the crystal facets' heterojunction to prevent carriers' recombination in CuSe. This double heterojunctions structure can sharply reduce the internal resistance and improve the carrier separation efficiency in order to improve the PEC and HER performances.