Synergistic effect between sulfur vacancies and S-scheme heterojunctions in WO3/VS-Zn3In2S6 for enhanced photocatalytic CO2 reduction in H2O vapor
Xiaoyan Zhang, Wenkang Ni, Xuanyu Yue, Zhijie Wang, Zizhong Zhang, Ke Wang, Wenxin Dai, Xianzhi Fu
Abstract
Converting CO 2 into CO, CH 4 , and other hydrocarbons using solar energy presents a viable approach for addressing energy shortages. In this study, photocatalysts with S-deficient WO 3 /Zn 3 In 2 S 6 (WO 3 /V S -ZIS) S-scheme heterojunctions have been successfully synthesized. Under UV–vis light irradiation, 20 %WO 3 /V S -ZIS demonstrated significantly improved CO 2 reduction activity and CH 4 selectivity. Detailed characterization and density functional theory (DFT) calculations reveal that the enhanced performance is due to the synergistic optimization of the S-scheme heterojunction and sulfur vacancies (V S ) for CO 2 reduction. The presence of V S aids in the adsorption and activation of CO 2 and enhances the separation of charge carriers. The 2D/2D S-scheme heterostructure assembled with WO 3 nanosheets not only accelerates the migration and separation of photoexcited charge carriers but also improves the adsorption of H 2 O and the formation of V S , thereby increasing the adsorption and activation of CO 2 and facilitating the protonation of CO* to produce CH 4 . This study clarifies the synergistic effect of V S and S-scheme heterostructures in improving photocatalytic performance, offering valuable insights into the photoactivation process of CO 2 at V S in S-scheme heterojunctions.