N-TiO2 synthesized by reflux method in H2O2-urea solution: point of zero charge, adsorption propertives, and photocatalytic activities under visible light

Abstract

Nitrogen-doped TiO₂ has been attractive because it showed photocatalytic activities under visible light. In this study, N-TiO₂ was synthesized by refluxing gel TiO₂ in the solutions of H₂O₂-urea. The influences of the concentration of urea and H₂O₂ solutions on photocatalytic activities of N-TiO₂ were investigated. Samples were characterized by XRD, IR, pH_PZC, BET, DRS. Adsorption and photocatalytic properties were studied by the degradation of methylene blue (MB) under visible light. The samples showed anatase phase with low crystalline, but high surface area. They had low pH_PZC of 1-1.5, and adsorbed well cation dyes such as MB. When the concentration of urea increased from 1 M to 2 M, and 3 M, the adsorption capacity increased, but the photocatalysis decreased. Sample with the highest photocatalytic activity was obtained when refluxing in the solution containing 10 mL H₂O₂.