Enhancing reactive oxygen species generation and photocatalytic performance via adding oxygen reduction reaction catalysts into the photocatalysts

In this work, a novel Ag 3 PO 4 @CoFe 2 O 4 composite photocatalyst was synthesized via a phosphate salts alkalinity adjustment strategy. Structure, morphology, and chemical component analysis indicated that the magnetic CoFe 2 O 4 nanoparticles (NPs) were evenly decorated on the surface of Ag 3 PO 4 particles, forming a sesame ball like structure. This unique structure ensures that the Ag 3 PO 4 @CoFe 2 O 4 composites could be totally separated by the magnet field. Photocatalytic water disinfection and organic pollutants degradation were employed to evaluate the photocatalytic performance of the as-prepared magnetic photocatalysts. The results showed that the optimum 3% Ag 3 PO 4 @CoFe 2 O 4 composite could completely inactivate 1*10 7 cfu/mL of Escherichia coli within 40 min, much faster than the pristine Ag 3 PO 4 . Meanwhile, the 3% Ag 3 PO 4 @CoFe 2 O 4 composite also showed a dramatic enhancement of photocatalytic activities for the organic pollutants degradation. The reactive oxygen species yield measurements, O 2 control photocurrents experiments, O 2 -TPD tests and photoluminescence spectra analysis indicate that the surface modification of CoFe 2 O 4 NPs could facilitate the O 2 adsorption and O O bond activation/cleavage/oxide removal and accelerate the two-electron oxygen reduction reaction for H 2 O 2 generation on the surface of Ag 3 PO 4 , and thus more ROSs were generated. In addition, due to the acceleration of electrons consumption, more holes will be left for the organic pollutants oxidation, and the photocatalytic activities as well as stability of Ag 3 PO 4 therefore have been greatly improved.