Photocatalytic activation of C-Br bond on facet-dependent BiOCl with oxygen vacancies

As typical persistent organic pollutants, polybrominated diphenyl ethers (PBDEs) have aroused high environmental concern due to their toxicity and recalcitrant degradation. Herein, the photocatalytic decabromodiphenyl ether (BDE209) removal performance was evaluated firstly on facet-dependent BiOCl with oxygen vacancies under irradiation (>360 nm). The results revealed that BDE209 was rapidly debrominated on {0   0   1} BiOCl with a reaction rate 4.4 times greater than that on {0   1   0} BiOCl under oxygen-free environment. Such a degradation order is completely opposite to that of Rhodamine B (RhB) degradation. This enhanced reduction is mainly attributed to the abundant oxygen vacancies on {0   0   1} facet of BiOCl, which act as adsorption sites for BDE209 to achieve C-Br bond activation efficiently. Meanwhile, debrominated products via meta- position have the highest proportion than that via ortho- and para- position in the first step. Therefore, a position-selective multi-electrons reduction mechanism is hypothesized. This study provides a new sight on C-X bond activation of halogenated aromatics by inducing oxygen vacancies on specific facets.