The enhancement of photodegradation efficiency using Pt-TiO₂catalyst

Abstract

This study investigates the mechanism of photosensitization and the recombination of excited electron–hole pairs affected by depositing platinum (Pt) on the surface of titanium dioxide (TiO₂). A new catalyst of Pt–TiO₂was prepared by a photoreduction process. Being model reactions, the photocatalytic oxidation of methylene blue (MB) and methyl orange (MO) in aqueous solutions using the Pt–TiO₂catalyst was carried out under either UV or visible light irradiation. The experimental results indicate that an optimal content of 0.75%Pt–TiO₂achieves the best photocatalytic performance of MB and MO degradation and that the Pt–TiO₂catalyst can be sensitized by visible light. The interaction of Pt and TiO₂was investigated by means of UV–Vis absorption spectra, photoluminescence emission spectra, and X-ray photoelectron emission spectroscopy. The Pt⁰, Pt²⁺ and Pt⁴⁺species existing on the surface of Pt–TiO₂, and the Ti³⁺ species existing in its lattice may form a defect energy level. The Pt impurities, including Pt, Pt(OH)₂, and PtO₂, and the defect energy level absorb visible light more efficiently in comparison with the pure TiO₂and hinder the recombination rate of excited electron–hole pairs.