Modular calcination strategy to construct defect-rich nitrogen-doped Nb2O5 for boosting photocatalytic oxidation of cyclohexane to cyclohexanone in solvent-free conditions

作者：Kuan Wang, Dan Wang, Xiaoyong Zhang, Junlei Wang, Shengli Lv, Zhen‐Hong He, Huan Wang, Weitao Wang, Yang Yang, Zhao‐Tie Liu · 发表于：Applied Surface Science · 年份：2023 · DOI：10.1016/j.apsusc.2023.156600 · 被引用次数：22 · 研究领域：Advanced Photocatalysis Techniques、TiO2 Photocatalysis and Solar Cells、Transition Metal Oxide Nanomaterials

The partial oxidation of cyclohexane (CHA) with oxygen to cyclohexanone (CHA-one) is one of the most transformation in the chemical industry in view that CHA-one is an irreplaceable raw material in the production of nylon. Herein, hydrogen, vacuum and air modules combined with ammonia module, respectively, were used to construct defect-rich nitrogen-doped Nb 2 O 5 . And, the calcination order and temperature were also considered to establish a modular calcination strategy. A series of modified N-doped Nb 2 O 5 were prepared by the proposed strategy, which were used to catalyze the photo-oxidation of CHA in solvent-free and room temperature conditions. Among these modified N-doped Nb 2 O 5 samples, the HN-Nb 2 O 5 possessed abundant chemical defects of oxygen vacancies and Nb 4+ , and achieved the best photocatalytic performance. Surprisingly, HN-Nb 2 O 5 achieved an amount of 130.35 μmol for CHA-one, which was approximately 2.2 and 26 times that of the pure Nb 2 O 5 and commercial Nb 2 O 5 , respectively, with up to 96.68% selectivity to CHA-one. The outstanding photocatalytic performance of the HN-Nb 2 O 5 can be ascribed to the presence of chemical defect-rich and the NO x species, enhanced light absorption and effective electron-hole separation. DFT calculations explained the promotion of the chemical defects and N doping on Nb 2 O 5 photocatalytic activity in terms of the band electron and band-gap level. The results of EPR analysis and scavenger tests found that e − is t...