Highly efficient photocatalytic degradation toward perfluorooctanoic acid by bromine doped BiOI with high exposure of (001) facet

Perfluorooctanoic acid (PFOA) is a highly persistent organic pollutant and being regulated in many countries. The strong chemical stability makes it a big challenge to degrade PFOA in aquatic environment. In this study, a high (001) facet exposed BiOI1-xBrx solid solution was successfully synthesized by doping bromine using solvothermal method. The prepared catalyst doped 5 % molar mass of Br (BiOI0.95Br0.05) displayed extremely high photocatalytic activity to PFOA under UV irradiation: 96 % of PFOA was decomposed within 120 min and similar to 65 % was mineralized within 180 min. The reaction kinetic constant was 4.3 times that of BiOI. The enlarged specific surface area, enhanced UV-light absorption and promoted separation of electron-hole pairs were responsible for the enhanced photocatalytic activity. The photogenerated electrons and holes were the decisive species for PFOA decomposition. Short chain perfluorocarboxylic acids (PFCAs), HCOOH, and - were generated and the possible degradation pathway of PFOA by BiOI0.95Br0.05 was proposed.