BiVO4/BiOCl Heterostructure Photoanodes for Highly Selective Photoelectrochemical Oxidation of Benzylic C(sp3)-H Bonds

Abstract

Photoelectrochemical (PEC) activation of benzylic C(sp3)-H bonds offers a sustainable and eco-friendly approach to synthesizing high-value chemicals. However, achieving high selectivity for desired products remains a significant challenge. In this study, we developed a BiOCl-modified BiVO4 (BiVO4/BiOCl) heterostructure photoanode for the PEC benzylic C(sp3)-H bonds oxidation. The p-n heterojunction formed between BiOCl and BiVO4 enhances charge carrier separation and transport, while the BiOCl surface layer facilitates the desorption of benzaldehyde. As a result, the optimized BiVO4/BiOCl photoanode demonstrated nearly 100% selectivity for benzaldehyde production and had similar applicability to a range of benzylic C(sp3)-H bond compounds. The reaction mechanism was further elucidated through in-situ FTIR spectroscopy. Additionally, a scalable flow cell integrating the BiVO4/BiOCl photoanode with a Pt/C-GDE electrode achieved a 77% selectivity in continuous toluene-to-benzaldehyde conversion, and the ability to activate the C(sp3)-H bonds using sunlight without bias was demonstrated. This work highlights a promising strategy for solar-driven organic synthesis, advancing the integration of renewable energy into chemical manufacturing.