Preparation of a composite photocatalyst with enhanced photocatalytic activity: Smaller TiO2 carried on SiO2 microsphere

In order to improve the photocatalytic activity of nano-TiO₂ and achieve its recovery, TiO₂/MS-SiO₂ photocatalyst is prepared when TiO₂ nanoparticles are distributed on the surface of amorphous SiO₂ microspheres (MS-SiO₂) through sol-gel method, and its composition and morphology structure are characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and transmission electron microscopy (TEM). Besides, the photocatalytic properties are tested and evaluated by degradation efficiency of methyl orange under ultraviolet light. The results show that TiO₂ nanoparticles uniformly dispersed on the surface of MS-SiO₂ and combined with MS-SiO₂ strongly by Ti-O-Si bond, whereas TiO₂ is anatase crystal and grain size is about 5 nm. Under ultraviolet light for 90 min, the degradation rate of TiO₂/MS-SiO₂ for methyl orange reached 100%, which is better than pure TiO₂ and P25. In addition, photocatalytic performance remains unchanged in a cyclic experiment. Transmission and separation efficiency of nano-TiO₂ photo-generated charge carriers is improved by loading on the surface of MS-SiO₂ so that MS-SiO₂ can enhance the photocatalytic performance of pure TiO₂. Moreover, this fact is illustrated by electron paramagnetic resonance intuitively.