Synthesis, characterization and photocatalytic activity of Bi-doped TiO 2 photocatalysts under simulated solar irradiation

Abstract

A series of Bi 3+-doped TiO 2 catalysts with a doping concentration up to 2 wt% were prepared by a sol–gel hydrothermal method. The prepared photocatalysts were characterized by different techniques to determine their structure, morphology and light absorption properties. The activities were evaluated in the photocatalytic oxidation of phenol in aqueous solution under UV–vis illumination. The experimental results indicate that the presence of Bi 3+ in TiO 2 catalysts enhances the photocatalytic reaction of phenol degradation, although the efficiency of the process markedly depends on the nominal content of the Bi 3+ and on the calcination temperature. It was found that the optimal dosage of 0.5 wt% Bi 3+ in TiO 2 and calcinations at 600 °C 4 h achieved the fastest reaction of phenol degradation under the experimental conditions. From the comparison of the initial rates of the photocatalytic degradation of phenol between home prepared undoped and Bi 3+-doped TiO 2 with commercial TiO 2 Degussa P25, it can be inferred that home prepared TiO 2 calcined at temperatures above 500 °C clearly exceed the photocatalytic performance of P25. When bismuth is incorporated, the reaction rate values are even higher, especially at 600 °C. Even when Bi 3+-doped TiO 2 (0.5 wt% Bi 3+) calcined at 600 °C has almost the same BET surface than P25, its activity is better. In particular, the reaction rate for the sample with a 0.5% mass content of Bi 3+ calcined at 600 °C not only present higher value with respect to the other series but also a degree of mineralization close to 100%.