K2TiO(C2O4)2-mediated synthesis of rutile TiO2 mesocrystals and their ability to assist photodegradation of sulfosalicylic acid in water

Abstract

Flower-like rutile TiO₂ mesocrystals were fabricated by a K₂TiO(C₂O₄)₂-mediated Ti–H₂O₂ interaction at 80 °C and under atmospheric pressure. Both thin films precipitated on the metallic Ti substrates and powders collected from the solutions were subjected to detailed characterizations of the nanostructures and photocatalytic performances. The Ti–H₂O₂ interaction at 80 °C resulted in arrays of hydrogen titanate nanowires on Ti substrates and the corresponding nanowires in the solution as well. With the additive of K₂TiO(C₂O₄)₂, flower-like rutile TiO₂ mesocrystals appeared via an oriented attachment self-assembly approach. The hydrogen titanate nanowires decomposed to anatase TiO₂ nanowires when heated in air at 450 °C; whilst the rutile TiO₂ mesocrystals remained unchanged upon the subsequent calcination. The photocatalytic activity of both thin films and powders after the calcination was evaluated by photodegradation of sulfosalicylic acid (SSA) in water under the UV light illumination. It was found that anatase favored the degradation of SSA rather than rutile; however, the larger specific surface area of mesocrystals, as well as the high charge separation rate inherent from their single crystal nature, compensated effectively the photocatalytic performance for the flower-like rutile TiO₂ mesocrystals.