Enhanced Photocatalytic Degradation of Methyl Orange by Metal‐Tio ₂ Nanoparticles

Abstract In this study, a series of transition metal‐doped TiO 2 was prepared by a simple sol‐solvothermal method. Mix an ethanol solution of tetrabutyl titanate and metal nitrate solution to obtain a homogeneous sol, which is then subjected to solvothermal treatment. After calcination, the metal‐TiO 2 naoncomposite was obtained. Selected transition metal precursors, including Cu, Fe, Ag, Cr, Co and Zn, were doped into TiO 2 nanocatalysts to assess photocatalytic degradation activities. The results show that 1 mol % Ag−TiO 2 photocatalyst has a larger specific surface area, a stable anatase phase and the narrowest forbidden band energy (3.00 eV). In photocatalytic degradation of methyl orange (MO) tests, 1 mol % Ag−TiO 2 could reach 100 % decolourisation after 70 min and 75.43 % mineralisation after 90 min. ESR analysis confirmed that Ag doping significantly increased the content of ⋅O 2 − and ⋅OH for the TiO 2 catalyst, which are responsible for the oxidation reactions and consequently degradation of pollutants. The photocatalytic degradation mechanism of MO was also proposed. The TOC analyses confirmed the mineralization of MO. The excellent thermal and chemical stability of 1 mol % Ag−TiO 2 has also been demonstrated by thermogravimetric analysis and cycling experiments. Electrochemical tests have also demonstrated the excellent electrochemical properties of 1 mol % Ag−TiO 2 .