Outstanding photo-thermo synergy in aerobic oxidation of cyclohexane by bismuth tungstate-bismuth oxychloride high-low heterojunction

Jia Zheng; Jincheng Liu; Xuyang Feng; Jiarong Liu; Shuang Zong; Lingling Liu; Yanxiong Fang

doi:10.1016/j.jcis.2023.07.172

Outstanding photo-thermo synergy in aerobic oxidation of cyclohexane by bismuth tungstate-bismuth oxychloride high-low heterojunction

J Colloid Interface Sci. 2023 Dec:651:304-318. doi: 10.1016/j.jcis.2023.07.172. Epub 2023 Jul 28.

Authors

Jia Zheng¹, Jincheng Liu², Xuyang Feng¹, Jiarong Liu¹, Shuang Zong¹, Lingling Liu¹, Yanxiong Fang¹

Affiliations

¹ Guangdong University of Technology, School of Light Industry & Chemical Engineering, Guangzhou Key Lab Clean Transport Energy Chemistry, Guangzhou 510006, China; Jieyang Branch of Chemistry and Chemical Engineering Guangdong Laboratory, Jieyang 515200, China.
² Guangdong University of Technology, School of Light Industry & Chemical Engineering, Guangzhou Key Lab Clean Transport Energy Chemistry, Guangzhou 510006, China; Jieyang Branch of Chemistry and Chemical Engineering Guangdong Laboratory, Jieyang 515200, China. Electronic address: jcliu@gdut.edu.cn.

PMID: 37544220
DOI: 10.1016/j.jcis.2023.07.172

Abstract

The difficulty of achieving both high conversion rate and high selectivity is a huge challenge in the catalytic aerobic oxidation of cyclohexane. In this paper, bismuth tungstate-bismuth oxychloride (Bi₂WO₆-BiOCl) nanoflower heterojunctions prepared via a one-step solvothermal process were applied in the photo-thermo synergetic catalytic oxidation of cyclohexane in the dried air. With the addition of little water at different reaction temperature, the ratio of bismuth to tungsten and the mass ratio of Bi₂WO₆ to BiOCl can be precisely tailored in the nanoflower sphere composites with thin nanosheets. Their microscopic morphology, elemental composition, crystal structure, and photoelectrochemical characteristics were explored by different characterization methods. The Bi₂WO₆-BiOCl composites possessed poor photocatalytic and thermal performances with the low conversion rates of 1.43% and 2.68%, respectively. However, through the photo-thermo catalytic oxidation process, an exceptional conversion rate of 13.32% was achieved with excellent selectivity of 99.22% for cyclohexanone and cyclohexanol (KA oil) using the same Bi₂WO₆-BiOCl composites. This superior performance outstrips Bi₂WO₆ flowers, BiOCl nanosheets and Bi₂WO₆-BiOCl composites with other compounding ratios. The creation of a high-low heterojunction in the Bi₂WO₆-BiOCl composite was confirmed by band energy analysis. The opto-electronic analysis, band energy analysis, sacrifice experiments, and active radical analysis were employed to elucidate the mechanism for the exceptional photo-thermo catalytic performance in detail. This work offers an exploratory solution to the challenges of high energy consumption and the difficulty in simultaneously achieving high selectivity and high conversion rates in cyclohexane oxidation, thus holding significant value.

Keywords: Bi(2)WO(6)-BiOCl; Cyclohexane oxidation; High-low heterojunction; KA oil; Photo-thermo catalysis.