Influence of TiO ₂ structure on its photocatalytic activity towards acetaldehyde decomposition

Sol-gel method was used for preparation of TiO ₂ having different structure and phase composition. Prepared titania samples were applied for acetaldehyde decomposition under UV light irradiation. The obtained results showed, that TiO ₂ consisted from mixed phases of anatase and brookite, which was prepared at neutral pH and calcined at 450 °C was the most active. Charge separation of free carriers was investigated by measurements of electron traps density. It was proved, that density of electron traps can be enhanced by nitrogen doping or by coexisting of two phases such as anatase and brookite. However nitrogen doping to TiO ₂ did not increase of its photocatalytic activity towards acetaldehyde decomposition. Therefore preparation of TiO ₂ having mixed phases of anatase and brookite appeared to be the most favourable towards elimination of acetaldehyde under UV at ambient conditions. Moreover, temperature of calcination such as 450 °C was the most optimal, because at that temperature total crystallisation of amorphous titnia occurrs and then interparticle contact increases, which facilitates the interfacial charge transfer between titania particles.