One-step and large-scale synthesis of anatase TiO2 mesocrystals along [001] orientation with enhanced photocatalytic performance

Abstract

Mesocrystals have attracted considerable attention due to their novel structure and special property, which are different from traditional polycrystals and single crystals. In this work, unique anatase TiO₂ mesocrystals along the [001] orientation were successfully synthesized on a large scale via a facile one-pot solvothermal method due to the synergistic effect of tetraethyl silicate (TEOS) stabilizer and sodium acetate trihydrate (NaAc·3H₂O) additive. Various characterization methods, including transmission electron microscopy (TEM), X-ray diffraction (XRD), N₂ adsorption–desorption isotherms, and X-ray photoelectron spectra (XPS), were applied to investigate the physicochemical properties of the as-prepared samples. The obtained anatase TiO₂ mesocrystals show the uniform and monodisperse spindle shape growing along the [001] direction and exhibit obvious mesoporous structure with a BET specific surface area of 85.3 m² g⁻¹_. The as-synthesized anatase TiO₂ mesocrystals have remarkable crystalline-phase stability and the pure anatase phase can be retained even when the sample is annealed at 1000 °C for 2 h. The formation mechanism and growth process of anatase TiO₂ mesocrystals was investigated with a few controlled experiments. The anatase TiO₂ mesocrystals exhibit high photocatalytic activity in the photodegradation of methylene blue (MB) dye and excellent photocatalytic H₂-evolution performance from water splitting with a Pt co-catalyst as a result of the high crystallinity, large specific surface area and proper crystal facets.