Construction of Indium Oxide/N-Doped Titanium Dioxide Hybrid Photocatalysts for Efficient and Selective Oxidation of Cyclohexane to Cyclohexanone
Kuan Wang, Bing Xue, Junlei Wang, Zhen‐Hong He, Songsong Li, Dan Wang, Weitao Wang, Yang Yang, Zhao‐Tie Liu
Abstract
Photocatalytic oxidation of cyclohexane (CHA) to generate cyclohexanone (CHA-one) is one of the most important strategic links for the production of nylon-6 and nylon-66. Herein, an indium oxide/N-doped titanium dioxide (In2O3/N-TiO2) hybrid photocatalyst with a p–n heterointerface was successfully constructed by a two-step strategy of the hydrothermal N-doped method and impregnation method with structural reconstruction. Under green and mild reaction conditions (room temperature, atmospheric pressure, and solvent-free), the In2O3/N-TiO2 hybrid catalyst achieved the desired photocatalytic performance for the production of CHA-one at simulated solar light. Compared with bare TiO2, the 5% In2O3/N-TiO2 composite achieved a 4-fold increase for producing CHA-one in catalytic activity and an increase in selectivity to the CHA-one of approximately 90%. Moreover, the In2O3/N-TiO2 composites exhibited a desirable cycling durability and recoverability. According to the photoelectrochemical tests and density functional theory (DFT) calculations, the enhanced photocatalytic performance of In2O3/N-TiO2 can be attributed to high visible-light absorption derived from N-doping and fast separation of photoformed electron–hole pairs caused by the p–n heterointerface. A possible photo-oxidation mechanism of CHA over the In2O3/N-TiO2 catalyst was proposed and verified by the trapping detection of active species. Thereby, the present approach provides a green and prospective strategy for extending the application of the TiO2-based photocatalyst for selective photo-oxidation.