Controllable synthesis of uniformly distributed hollow rutile TiO2 hierarchical microspheres and their improved photocatalysis

We reported the controllable synthesis of uniformly distributed hierarchical hollow microspheres composed of rutile TiO2 nanorods as building blocks, prepared by a hydrothermal method without employing any templates/substrates or surfactants. The homogenous hollow microspheres were obtained by optimizing the experimental conditions including hydrothermal temperatures and tetrabutyl titanate (TBOT) concentrations. A detailed formation mechanism was also proposed. The samples were analyzed by Brunauer–Emmett–Teller (BET) specific surface area analysis and ultraviolet–visible (UV–Vis) diffuse reflectance spectra (DRS). The photocatalytic results for methylene orange (MO) degradation showed that the hollow hierarchical microspheres exhibited the best photocatalytic activity among the as-synthesized products. Further optimum photocatalytic conditions were determined to study the degradation rate, decolorization and TOC (total organic carbon) removal efficiencies, and reaction kinetics in detail. Under optimum conditions, the contrastive photocatalytic experiments indicated that the photocatalytic activity was enhanced markedly when assembling the single-crystal rutile TiO2 nanorods into hollow hierarchical microstructures.