In-situ homologous bromine vacancies for enhanced C-Br bond activation and rapid debromination of decabromodiphenyl ether

Polybrominated diphenyl ethers (PBDEs) have attracted increasing attention due to their biotoxicity and persistence. Herein, rapid degradation of decabromodiphenyl ether (BDE209) was achieved on bromine vacancies enriched BiOBr (BOB-V_Br) nanosheets, with a degradation rate for BDE209 under visible light irradiation (λ > 400 nm) exceeding 95 % within 6 min. The initial two minutes serve as an induction period, during which the Br vacancies were in-situ introduced into the BiOBr (BOB) nanosheets. By precisely controlling the duration of photoinduction, varying concentrations of Br vacancies were successfully generated on the surface of the BOB nanosheets. Consequently, an enhanced degradation rate of BDE209 was observed in direct correlation with the increased concentration of Br vacancies. BOB-V_Br showed a remarkable selectivity of 74 % for meta-product (BDE207). This selectivity towards BDE207 surpasses that of other anionic vacancies, as oxygen, sulfur, and iodine vacancies. The in-situ generated Br vacancies help to accommodate the Br atom of BDE209 in atomic size and electronic structure, thus facilitating the activation of the C-Br bond and achieving rapid BDE209 debromination. This work provides a new insight for the treatment of organic halogenated pollutants by photocatalysts with homologous halogen vacancies.