Degradation of Methylene Blue by Sol-Gel One-Step Method with B-W Co-doped TiO 2

In this work, B-W co-doped TiO2 photocatalysts were synthesized by a sol-gel method using ammonium metatungstate and boric acid as W and B sources, respectively. The effects of W/Ti and B/Ti ratios on the photocatalytic activities were investigated. When W/Ti = 3.5/100 and B/Ti = 5/100, the degradation rate of a 40 mg/L methylene blue solution reached 82.45% within 120 min and the quasi-first-order kinetic constants were 12.39 times and 1.89 times of the quasi-first-order kinetic constants of pure TiO2 and 3.5%W-TiO2, respectively. The characterization results showed that the modified TiO2 crystal type obtained by W and B co-doping was anatase, and the gel was calcined to produce substituted W doping and interstitial B doping (Ti-O-B-Ti). W and B doping can form impurity energy levels below the conduction band and above the valence band, respectively; under their synergistic effect, the bandgap of 5%B-3.5%W-TiO2 was reduced to 2.65 eV, which lowered the the compounding efficiency of the hole-electron pairs and improved the photocatalytic performance.