Improved photocatalytic activity of ZnO via the modification of In2O3 and MoS2 surface species for the photoreduction of CO2

Highlights: • ZnO–In₂O₃X%/MoS₂Y% has a higher photocatalytic activity for CO₂ photoreduction. • The In₂O₃ and MoS₂ species form photo-generated charge carriers' transport channels. • The surface species promote a better match between the energy level and redox potential. • It is an efficient method to prepare high catalytic activity materials by surface modification. Herein, a series of In₂O₃ and MoS₂ surface-bound active species co-modified using ZnO nanorods (ZnO–In₂O₃X%/MoS₂Y%) were synthesized via a hydrothermal method. X-ray diffraction (XRD), High–resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), UV–Vis absorption, and fluorescence spectroscopy, as well as time-resolved photoluminescence decay curves, have shown that In₂O₃ and MoS₂ were the active species co-modified on the surface of ZnO. The band structure of the resulting photocatalysts was determined via characterization experiments combined with theoretical calculations, and the behavior of the photo-generated electrons and holes were investigated. We noted that the In₂O₃ and MoS₂ surface-bound active species generated transfer channels for the holes and electrons, respectively. For the CO₂ photoreduction reaction, the ZnO–In₂O₃X%/MoS₂Y% photocatalysts exhibited improved performance due to the contribution of the surface species during the efficient separation of the photo-generated electrons and holes; this enhanced the visible light absorption capacity and, thus, the catalyst's band structure matching with the redox potential of CO₂ photoreduction. This paper provides a new strategy for designing and preparing novel photocatalysts with surface-bound active sites and high photocatalytic performance.