Surface Engineered BiVO₄ for Photoelectrochemical Alkene Epoxidation via Bromine Mediation

Selective epoxidation of alkenes is essential in organic synthesis, yet achieving it under mild conditions presents significant challenges. Photoelectrochemical (PEC) alkene epoxidation driven by hypobromite (BrO^–, Br⁺) formation offers a green and sustainable route, and enhancing Br⁺ production is essential for achieving high product selectivity. A synergistic strategy that integrates water oxidation to hydrogen peroxide with bromide oxidation to bromine (Br₂) using a surface engineered BiVO₄ photoanode is presented. In situ generated H₂O₂ and Br₂ yield BrO^–, which serves as an active brominating (Br⁺) agent for alkene epoxidation. Consequently, the surface engineered BiVO₄ photoanode achieves over 98.1 ± 0.79% conversion rate and 91.9 ± 0.99% selectivity across various alkenes. An unbiased PEC tandem device is constructed by coupling a BiVO₄ photoanode for styrene epoxidation with a Cu₂O photocathode for hydrogen production, achieving simultaneous styrene oxide production with 86.4% selectivity and hydrogen production. Our work provides new insights into PEC organic synthesis and hydrogen production.