Effects of amount of Si addition and annealing treatment on the photocatalytic activities of N- and Si-codoped titanias under visible-light irradiation

Silicon-modified titanias prepared by thermal reactions of mixtures of titanium tetraisopropoxide and tetraethyl orthosilicate with various ratios in 1,4-butanediol at 300 °C (glycothermal reaction) were calcined at 500 °C in air, treated in an NH3 flow at 600 °C for 1 h, and then annealed in air at different temperatures. The properties of the thus-obtained nitrified Si-modified titanias were characterized by UV−vis diffuse reflectance spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, nitrogen adsorption, and electron spin resonance. The products had absorptions in the visible-light region and exhibited photocatalytic activities for decomposition of acetaldehyde under visible-light irradiation. It was found that the amount of Si modification significantly affected the amount of doped nitrogen and the visible-light-induced photocatalytic activity. Higher annealing temperature (500 °C) decreased the population of oxygen vacancies and increased photocatalytic activity in spite of the fact t...