Effect of triblock copolymers on crystal growth and the photocatalytic activity of anatase TiO2 single crystals

Abstract

In order to evaluate the effect of a triblock copolymer on the growth of TiO₂ crystals, anatase TiO₂ crystals with different morphologies and structures were synthesized by controlling the content and type of triblock copolymer in the solvothermal route. The resulting samples were characterized by XRD, XPS, SEM, TEM and EDX. The characterization results show that hydrofluoric acid can promote the formation of highly active (001) facets by the formation of a Ti–F bond. The triblock copolymers (P123 and F127) refine the surface structure of polycrystalline spherical TiO₂ and make the crystal surface homogeneous and smooth. Moreover, P123 causes the agglomeration effect and hinders the recrystallization process of anatase TiO₂ single crystals, and this will lead to corrosion of the crystal facets. Meanwhile, F127 destroys crystal formation and hinders crystal growth due to its special micelle structure. In addition, research on the photocatalytic activity proposed that the integrity of the (001) and (101) facets was a critical factor in the photocatalytic reaction. The resultant anatase TiO₂ single crystals could produce more hydroxyl radicals (˙OH) in the photocatalytic system, which exhibited remarkable photocatalytic performance for the degradation of three types of dye.