Visible-light-active TiO2 photocatalyst for efficient photodegradation of organic dyes

Abstract

Design and synthesis of low-cost visible-light-active catalysts for photodegradation of organic dyes has been regarded as an efficient way for the utilization of solar energy to address the environmental issues. In this work, visible-light-active TiO2 photocatalyst were synthesized via a simple solvothermal method by reaction of tetrabutyl titanate and oleylamine in the presence of 1, 2-ethanedithiol. The resulting TiO2 (T-S) possesses of a broadband visible light absorption capacity, with the absorption band edge of ~574 nm. UV–vis absorption spectroscopy and Mott-Schottky curve measurements demonstrate that the band gap of T-S can be reduced to ~2.16 eV with the conduction band of −0.58 eV compared to that of typical P25 (~3.21 eV). As a result, the T-S sample exhibits efficient photocatalytic performance for removal of rhodamine B (Rh B) and methylene blue (MB). Under visible light irradiation, the photodegradation efficiency can reach to as high as >95% in 60 min for Rh B and MB (10 mg/L). A probable charge carrier transport path for this photocatalytic process, where the photo-generated e−, h+ and forming oxygen species •O2−, •OH under visible light irradiation cooperatively catalyze the molecules of Rh B and MB in solution. This work put forward a simple strategy for synthesizing visible-light-active photocatalytic materials.