Morphology control of 3D hierarchical urchin-like hollow SiO2@TiO2 spheres for photocatalytic degradation: Influence of calcination temperature

A novel 3D hierarchical urchin-like SiO2@TiO2 sphere with hollow structure and anatase-rutile biphase (3D-UHST) was synthesized via solvothermal process, followed by calcination at various temperatures. The morphology and structure of the synthesized 3D-UHSTs were characterized by SEM, TEM and XRD. A series of SEM characterization results showed that the solvothermal reaction time and the presence of glycerol had significant effects on the construction of 3D urchin-like structures, and its growth mechanism was also obtained. Furthermore, the effects of calcination temperature on the crystal structure and photocatalytic degradation of RhB were systematically studied. It was found that the 3D-UHSTs prepared at a calcination temperature of 700 °C had higher photocatalytic activity, which was due to the electron transfer caused by the SiO2@TiO2 core@shell structure and the anatase-rutile biphase. Aggregation of photo-generated electrons occurred in the rutile phase and the SiO2 shell, which reduced the possibility of electron/hole recombination. When irradiated with ultraviolet light for 35 min, the degradation rate of UHSTs-700 was up to 82.2%. The photocatalytic degradation reaction was well accorded with the first-order reaction kinetics, with a rate constant of 0.04654 min−1. •A novel 3D hierarchical urchin-like SiO2@TiO2 sphere with hollow structure and anatase-rutile biphase was synthesized.•The Ti-Gly transition played a decisive role in the formation of 3D urchin-like structures.•The spheres exhibited the enhanced photocatalytic performance with a rate constant of 0.04654 min−1.