Comparisons of visible-light driven photocatalytic CO2 conversion performances over mesoporous CdSxSe1–x with different molecular compositions

Abstract

This study presents a synthesis method for nanowire arrayed mesoporous CdSxSe1-x compounds with different S/Se molar ratios. Both ternary and binary compound semiconductors are synthesized by hard-templating using SBA-15 as a silica template. The synthesized mesoporous materials have high specific surface areas of approximately 65–100 m2 g−1 and remarkable light absorption properties in the UV to visible light region (1.7–2.4 eV), and thus they are appropriate for the photo-conversion of CO2 into CO and CH4. The results show that the compositions of CdSxSe1-x excellently agree with the compositions of the reactants. Moreover, the band gaps of the mesoporous CdSxSe1-x samples could be directly tuned by varying the composition of the reactants. It is concluded that mesoporous CdSe achieves the highest CH4 yield rate, i.e., 0.382 μmol gcat–1 h–1, and CdS0.5Se0.5 achieves the highest CO yield rate (among all the samples synthesized), i.e., 5.633 μmol gcat–1 h–1. Also, it is found that the CO2 photoconversion performance on mesoporous II-VI photocatalyst are highly affected by CO2 adsorption capacities and photo-generated charge separation.