Mechanism of Ag-enhanced CuBi2O4 inactivation of Escherichia coli in a photocatalytic Fenton system

In this work, Ag/CuBi 2 O 4 composite photocatalyst films with excellent photocatalytic sterilization properties were prepared by photodeposition. The photocatalytic activity of silver-modified CuBi 2 O 4 (Ag/CuBi 2 O 4 ) under the photocatalytic-Fenton coupling system was verified by its inactivation rate of Escherichia coli in seawater. The results showed that the photocatalytic sterilizing performance of CuBi 2 O 4 loaded with Ag in the presence of trace amounts of H 2 O 2 was significantly improved. 15Ag/CuBi 2 O 4 possessed the optimal photocatalytic activity, and its sterilizing rate in 30 min could reach 96.6%. Its sterilization rate in 30 min could reach 96.6%, which is about 70% higher than that of pure CuBi 2 O 4 . Meanwhile, the mechanism of the enhanced sterilization performance of Ag/CuBi 2 O 4 in the photocatalytic-Fenton coupled system was investigated. Firstly, according to the electrochemical results, the loading of Ag can significantly improve the charge separation efficiency of CuBi 2 O 4 . And promotes the conversion of H 2 O 2 to hydroxyl radicals(·OH); Secondly, the valence band potential of 15Ag/CuBi 2 O 4 is more positive than that of CuBi 2 O 4 , which suggests that Ag loading can enhance the oxidation of CuBi 2 O 4 cavities. Comprehensive radical trapping experiments demonstrate that ·OH and holes (h + ) are the main active species for inactivating Escherichia coli (E. coli). In this work, effective conversion of H 2 O 2 to ·OH in a wide spectral range was achieved by loading Ag nanoparticles on the surface of CuBi 2 O 4 , which provides a new idea for the development of photocatalytic-Fenton coupling technology and ballast water treatment. Graphical abstract