Bromide-Mediated Photoelectrochemical Epoxidation of Alkenes Using Water as an Oxygen Source with Conversion Efficiency and Selectivity up to 100

• Published in: Journal of the American Chemical Society 2022-11, Vol.144 (43), p.19770-19777
• Main Authors: Liu, Xiao, Chen, Zhi, Xu, Suxian, Liu, Guoquan, Zhu, Yong, Yu, Xiaoqiang, Sun, Licheng, Li, Fei
• Format: Article
• Language: English
• Subjects: alkene; Alkenes; Bismuth compounds; bromide; Bromides; Catalyst selectivity; chemical bond; chemical modification; chemical structure; corrosion; electrochemical analysis; Energy conservation; epoxidation; Epoxidation of alkenes; epoxide; Epoxy Compounds; Hydrogen; Hydrogen production; Hydrogen-evolution; liquid chromatography-mass spectrometry; Mesoporous; Oxidation; Oxidation of organic substrates; Oxygen; Oxygen sources; Photo-anodes; Photo-electrochemical oxidations; Photochemical Processes; photochemistry; photodegradation; Photoelectrochemicals; physical chemistry; physical parameters; Precious metals; proton nuclear magnetic resonance; Redox mediators; room temperature; scanning electron microscopy; Sodium compounds; Solar fuels; Solar power generation; Substrates; synthesis; Water; X ray diffraction
• ISSN: 0002-7863; 1520-5126; 1520-5126
• DOI: 10.1021/jacs.2c06273

In a photoelectrochemical (PEC) cell, the production of solar fuels such as hydrogen is often accompanied either by the oxidation of water or by the oxidation of organic substrates. In this study, we report bromide-mediated PEC oxidation of alkenes at a mesoporous BiVO4 photoanode and simultaneous hydrogen evolution at the cathode using water as an oxygen source. NaBr as a redox mediator was demonstrated to play a dual role in the PEC organic synthesis, which facilitates the selective oxidation of alkenes into epoxides and suppresses the photocorrosion of BiVO4 in water. This method enables a near-quantitative yield and 100% selectivity for the conversion of water-soluble alkenes into their epoxides in H2O/CH3CN solution (v/v, 4/1) under simulated sunlight without the use of noble metal-containing catalysts or toxic oxidants. The maximum solar-to-electricity efficiency of 0.58% was obtained at 0.39 V vs Ag/AgCl. The obtained epoxide products such as glycidol are important building blocks of the chemical industry. Our results provide an energy-saving and environment-benign approach for producing value-added chemicals coupled with solar fuel generation.