C vacancy and F decorated g-C3N4 for boosting photocatalytic ozonation of sodium p-perfluorinated nonoxybenzenesulfonate

Photocatalytic ozonation (PCO) was a novel water treatment method, but the low photo-generated electron ( e - ) utilization and ambiguous ROS formation mechanism restrained its performance. Herein, C vacancy and F co-decorated g-C 3 N 4 (FCN_Cv) was designed to accelerate the PCO performance with sodium p -perfluorinated nonoxybenzenesulfonate (OBS) acting as model pollutant. Comparative characterizations revealed that FCN_Cv remained the inherent structure of g-C 3 N 4 (BCN), and had an enhanced conduction band potential, narrower band gap and longer e - lifetime. FCN_Cv exhibited the greater activity over BCN, with 99.3 % OBS removal in 30 min but only 78.3 % for BCN during PCO process. •OH was the main ROS for degrading OBS. The greater •OH yield was obtained by FCN_Cv PCO process because of the increase of e - utilization. On one hand, the two electrons reduction of O 2 into H 2 O 2 on FCN_Cv was accelerated, which triggered the peroxone reaction between photogenerated-H 2 O 2 and O 3 . On the other hand, the direct one electron reduction of O 3 by e - also accounted for •OH generation. 17 kinds of intermediates were detected and the OBS degradation routes were inferred, which was involved with hydroxylation, C-O cleavage and aromatic ring opening reactions. Overall, this study demonstrated the feasibility of decorating F element and C vacancy on g-C 3 N 4 in enhancing e - utilization and •OH generation during PCO process as well as deepened the understanding of fate of OBS in PCO process.