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 mesopomus materials have high specific surface areas of approximately 65-100 m(2) 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 mesopomus 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 mu mol gcat(-1) h(-1), and CdS0.5Se0.5 achieves the highest CO yield rate (among all the samples synthesized), i.e., 5.633 mu mol 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.