Tailoring <i>p‐p</i> Orbital Hybridization via Oxygen Vacancy in Bismuth Oxybromide Heterojunctions for Efficient Photocatalytic CO ₂ Reduction

Abstract Oxygen vacancies (Ovs) are considered potentially important in photocatalytic CO 2 reduction, yet effectively activating CO 2 and regulating key intermediates toward the target product by Ovs in heterostructure remains challenging. Herein, an Ov‐engineered BiOBr/In 2 O 3 heterojunction (BOvIN) is constructed under polyvinylpyrrolidone (PVP) regulation, which induces the formation of Ov near Bi─O bonds. Experimental and theoretical results indicate that Ov can modify the Bi‐6 p electronic structure to strengthen the interaction with CO 2 , which further regulates the orbital hybridization between Bi‐6 p and C‐2 p ( * COOH), thereby facilitating the rate‐determining step ( * CO 2 → * COOH). Furthermore, the BOvIN S‐scheme heterojunction, featuring an internal built‐in electric field and Ovs‐induced defect states, not only enables CO 2 reduction on BiOBr and H 2 O oxidation on In 2 O 3 with high redox capacity, but also significantly reduces photoexcited charge recombination. Consequently, the BOvIN exhibits a competitive CO production rate of 341.60 µmol g −1 h −1 with ≈100% selectivity in pure water, achieving a record apparent quantum efficiency of 3.55% at 420 nm. This work offers a new perspective on optimizing intermediate adsorption by tuning electronic structure through advanced photocatalysts for efficient and selective photocatalytic CO 2 conversion.