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

- Sesame ball like Ag3PO4@CoFe2O4 nanostructure magnetic photocatalyst was synthesized successfully.
- The Ag3PO4@CoFe2O4 photocatalysts exhibit excellent photocatalytic disinfection and organic pollutants degradation.
- Revealed that modification of CoFe2O4 facilitated the O2 adsorption and OO bond activation/cleavage/oxide removal.
- Demonstrated that the surface catalysis engineering can serve as a versatile approach to refine catalysts.

In this work, a novel Ag3PO4@CoFe2O4 composite photocatalyst was synthesized via a phosphate salts alkalinity adjustment strategy. Structure, morphology, and chemical component analysis indicated that the magnetic CoFe2O4 nanoparticles (NPs) were evenly decorated on the surface of Ag3PO4 particles, forming a sesame ball like structure. This unique structure ensures that the Ag3PO4@CoFe2O4 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% Ag3PO4@CoFe2O4 composite could completely inactivate 1*107 cfu/mL of Escherichia coli within 40 min, much faster than the pristine Ag3PO4. Meanwhile, the 3% Ag3PO4@CoFe2O4 composite also showed a dramatic enhancement of photocatalytic activities for the organic pollutants degradation. The reactive oxygen species yield measurements, O2 control photocurrents experiments, O2-TPD tests and photoluminescence spectra analysis indicate that the surface modification of CoFe2O4 NPs could facilitate the O2 adsorption and OO bond activation/cleavage/oxide removal and accelerate the two-electron oxygen reduction reaction for H2O2 generation on the surface of Ag3PO4, 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 Ag3PO4 therefore have been greatly improved.

The CoFe2O4 NPs possess specific catalyzing properties, which can effectively catalyze the two-electron oxygen reduction reaction for H2O2 generation on the surface of Ag3PO4@CoFe2O4 composites. The photocatalytic water disinfection and organic pollutants degradation efficiency can be greatly improved.80