Optimized preparation of Co-Pi decorated g-C3N4@ZnO shell-core nanorod array for its improved photoelectrochemical performance and stability

Abstract

The cobalt-phosphate (Co-Pi) decorated g-C3N4@ZnO shell-core nanorod array (Co-Pi/g-C3N4@ZnO NRA) photoanode with broadened spectral response and optimized photoelectrochemical (PEC) performance was prepared. The g-C3N4@ZnO NRA was prepared via improved urea impregnation and calcination methods in semi enclosed environment. The g-C3N4 flexible slice shell was uniformly wrapped on ZnO nanorods core and the intimately contacted heterojunction was formed between the interface of g-C3N4 and ZnO. The g-C3N4@ZnO NRA promotes the separation and transfer of the photogenerated electron-hole pairs on g-C3N4 and ZnO under either visible light or white light illumination. The prepared g-C3N4@ZnO NRA was further electrodeposited with Co-Pi nanoparticles (NPs). The Co-Pi NPs can assist in the consumption of the photoinduced holes as well as pull the Fermi level potential of g-C3N4@ZnO NRAs towards the positive direction, resulting in the upward band bending at the band-edge position for Co-Pi/g-C3N4@ZnO NRAs and promoting the separation efficiency of the photogenerated electron-hole pairs. Consequently, the Co-Pi/g-C3N4@ZnO NRA exhibits an improved PEC performance under both visible light and white light illumination. In addition, g-C3N4 flexible slice shell decorated with Co-Pi NPs covered on the surface of ZnO NRAs core improved the stability of the ZnO NRA photoanode.