Hydrothermal synthesis of mixed phase blue titanium dioxide from oxalate stabilised sols

Abstract

Blue coloured titanium dioxide nanoparticles were synthesised by the hydrothermal treatment of oxalic acid stabilised titania sols in the presence of NH 4 F as a modifying agent. The NH 4 F concentration determined the phase of titania produced and influenced the shape of the rutile crystallites produced. The blue colour originated from the F-stabilised Ti 3+ centres formed under the reaction conditions. Organic residues in the sol decomposed to generate a hydrogen-rich atmosphere. Photocatalytic activity studies revealed the rutile phase titania produced was extremely active for a given surface area when compared to P-25.