Rapid charge transfer via anion bridge strategy for enhanced deep photocatalytic NO oxidation

Abstract

Surface defect engineering and interfacial heterojunction construction can provide a promising strategy to achieving efficient reactant molecular activation and rapid charge transfer. However, traditional surface defect and interfacial heterojunction could often suffer from the potential space barrier, sluggish electron transfer, and weak reactant adsorption/activation, resulting in unsatisfactory pollutant removal effect. Herein, the anions (WO₄²⁻) bridged AgBr/Bi₄O₅Br₂ heterojunction, involves the in situ growth of AgBr onto Bi₄O₅Br₂ with the generation of bromine vacancies (BVs), is designed and synthesized by using a chemical deposition method. By establishing an electron-bridge into the interface of AgBr and Bi₄O₅Br₂, a rapid charge carrier transfer channel is created, efficiently promoting the transport of photogenerated electrons from AgBr to Bi₄O₅Br₂. Importantly, these spatially separated electrons of AgBr-WO₄²⁻-Bi₄O₅Br₂ are captured by the active sites (BVs) in Bi₄O₅Br₂to promote reactant activation, resulting in highly stable photocatalytic NO removal (67.7 %) and efficient inhibition of toxic NO₂ formation (417.9 ppb → 30.6 ppb). The effective removal of NO₂ by other anions, such as PO₄^3-, demonstrates the broad applicability of this approach. This work introduces a synergistic mechanism of electron bridge, built-in electric field and vacancy engineering to create rapid charge carrier transfer channel and molecular activation strategy in designing highly efficient photocatalysts for deep photocatalytic NO oxidation.