A p-n heterojunction NiS-sensitized TiO2 photocatalytic system for efficient photoreduction of carbon dioxide to methane

Nanoparticles of the p-type semiconductor nickel sulfide are grown on a highly aligned n-type TiO2 film. Using XRD, XPS, EDS, UV-Vis diffuse reflectance spectroscopy, photoluminescence, photocurrent density, and CO2-TPD, the physicochemical characteristics of the p-n heterojunction NiS-sensitized TiO2 films are investigated. The highest photocurrent is obtained for the optimized 0.10 M NiS-sensitized TiO2 film, which resulted in eventually decreasing the electron-hole recombination during CO2 photoreduction. The NiS-sensitized TiO2 film exhibits superior photocatalytic behavior compared to that of a pure TiO2 film. A model for investigating the catalytic activity of the NiS-sensitized TiO2 film for CO2 photoreduction is proposed.