Surface hydroxylation of TiO2/g-C3N4 photocatalyst for photo-Fenton degradation of tetracycline

Abstract The photocatalytic degradation of tetracycline in aqueous solution is a typical heterogeneous reaction, and thus the design of efficient photocatalysts for tetracycline degradation should revolve the process features of heterogeneous reaction closely. In the present work, TiO2-P/g-C3N4 composites with abundant surface hydroxyls were prepared by coupled g-C3N4 nanosheets with plasma treated TiO2 (TiO2-P) nanoparticles. The resultant TiO2-P/g-C3N4 as photocatalysts showed higher activity for the degradation of tetracycline in aqueous solution than g-C3N4, TiO2, TiO2-P and TiO2/g-C3N4 under visible light irradiation. The better activity of TiO2-P/g-C3N4 photocatalysts for tetracycline degradation could be ascribed to the good synergy between TiO2-P and g-C3N4. Specifically, due to the presence of surface hydroxyls on TiO2-P, the tetracycline adsorption activity, electrons-holes separation property as well as H2O2 activating activity of TiO2-P/g-C3N4 during tetracycline degradation were improved. By integrating the property of g-C3N4 photocatalyst in H2O2 production, as well as the property of TiO2-P in activating H2O2 into •OH and •O2-, efficient photo-Fenton degradation of tetracycline was achieved in the TiO2-P/g-C3N4 photocatalytic system. Our study on TiO2/g-C3N4 composite photocatalyst provides helpful inspiration to design photocatalysts with high-activity for the photo-Fenton degradation of organic pollutants.