Construction of oxygen-deficient In2O3/ZnIn2S4 with hollow tubular heterostructure for photocatalytic CO2 reduction to syngas and benzyl alcohol oxidation

Abstract

To reduce the recombination of the photogenerated charge carriers (PCCs), increase the utilization of the PCCs may be an effective method. In this work, the heterojunction catalysts of MIL-68 derived In2O3 (IO) microtube and ZnIn2S4 (ZIS) nanosheets were prepared by self-template and in-situ growth strategy. By growing ZnIn2S4 nanosheets on the surface of oxygen-deficient IO microtube, these two distinct semiconductors are integrated into hierarchical tubular hybrids with heterogeneous interfacial contacts. To improve the utilization rate of PCCs, the photocatalytic CO2 reduction is proceeded on IO/ZIS composite coupling with benzyl alcohol (PhCH2OH) oxidation. With the mass ratio of IO and ZIS adjusted, 30% IO/ZIS performs the best photocatalytic activity of CO2 reduction, which is 64.19 times higher than that of pure ZIS. The largely enhanced photocatalytic activity of IO/ZIS is attributed to the intimate interfacial contacts between IO and ZIS, which accelerates the separation and migration of PCCs via the Z-scheme model. The separated electrons and holes are respectively participated in the CO2 reduction and the PhCH2OH oxidation, as the reduction and oxidation products are close to 1: 1. This work not only provides the guideline for the design and construction of complex semiconductor-based photocatalysts, but an effective way to increase the utilization of PCCs.