BiVO ₄ /BiOCl heterostructure photoanodes for highly selective photoelectrochemical oxidation of benzylic C(sp ³ )–H bonds

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 oxidation of benzylic C(sp³)-H bonds. 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 <i>in situ</i> FTIR spectroscopy. Additionally, a scalable flow cell integrating the BiVO₄/BiOCl photoanode with a Pt/C-GDE 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.