Construction of an all-solid-state artificial Z-scheme system consisting of BiWO/Au/CdS nanostructure for photocatalytic CO reduction into renewable hydrocarbon fuel.

An all-solid-state BiWO/Au/CdS Z-scheme system was constructed for the photocatalytic reduction of CO into methane in the presence of water vapor. This Z-scheme consists of ultrathin BiWO nanoplates and CdS nanoparticles as photocatalysts, and a Au nanoparticle as a solid electron mediator offering a high speed charge transfer channel and leading to more efficient spatial separation of electron-hole pairs. The photo-generated electrons from the conduction band (CB) of BiWO transfer to the Au, and then release to the valence band (VB) of CdS to recombine with the holes of CdS. It allows the electrons remaining in the CB of CdS and holes in the VB of BiWO to possess strong reduction and oxidation powers, respectively, leading the BiWO/Au/CdS to exhibit high photocatalytic reduction of CO, relative to bare BiWO, BiWO/Au, and BiWO/CdS. The depressed hole density on CdS also enhances the stability of the CdS against photocorrosion.