Efficient photocatalytic defluorination of perfluorooctanoic acid over BiOCl nanosheets via a hole direct oxidation mechanism

There remains a significant need for developing new photocatalytic system to degrade perfluorooctanoic acid (PFOA), a typical persistent organic pollutant. In this study, highly efficient BiOCl nanosheets were prepared by a simple hydrolytic method and employed to decompose PFOA. The UV irradiation BiOCl system decomposed nearly all the added PFOA after 12   h, yielding a defluorination of 59.3% and a minimization ratio of 52.5%. The photocatalytic defluorination rate constant of PFOA on BiOCl was 16.53   μmol   L −1   h −1 , being 1.7 and 14.6 times higher than that on commercial In 2 O 3 and TiO 2 (P25), respectively. It was demonstrated the photocatalytic degradation of PFOA on BiOCl mainly followed the direct hole-induced oxidative pathway, and the PFOA degradation was positively correlated with the amount of oxygen vacancies in BiOCl. The oxygen vacancies not only acted as the electron scavengers to suppress the charge recombination, but also favored to bind PFOA tightly on the BiOCl surface through a special monodentate coordination, which is beneficial for the hole oxidation of PFOA.