Effect of additives on photocatalytic activity of titanium dioxide powders synthesized by thermal plasma

Abstract TiO 2 nanopowder was synthesized from titanium tetrachloride in a thermal plasma reactor. To improve photocatalytic activity, silicon tetrachloride and iron(III) acetylacetonate were added to the plasma reactor. The photocatalytic activity of prepared pure TiO 2 (T-powder), Si-doped TiO 2 (ST) and Fe-doped TiO 2 (FT) powder was evaluated by photodegradation of acetaldehyde. Decomposition efficiency of T-powder under UV-light was increased with the content of anatase. A small amount of Si-dopant improved the photocatalytic activity, while excessive Si-dopant over 2% decreased the photocatalytic activity of ST-powder because of the reduction of active sites on the catalyst. FT-powder was tested for the photocatalytic activity under visible light and UV-light. Decomposition efficiency increased with the addition of Fe-dopant because of suppression of electron–holes recombination. However, excessive Fe-dopant by over 15% inhibited the crystallization of anatase and acted as recombination center, leading to decrease the decomposition efficiency.