Effect of calcination temperature on the structure and properties of SiO2 microspheres/nano-TiO2 composites

Abstract

The silica microspheres surface-coated nano-TiO2 composite material (MS-SiO2/TiO2) was prepared by co-grinding the silica microspheres (MS-SiO2) and nano titanium dioxide soliquid (nano-TiO2-sol) in a stirring mill, and then calcining the above grinding products. The photocatalytic performance (methyl orange as the target pollutant) and surface photoinduced hydrophilicity of MS-SiO2/TiO2 calcined at different temperatures were tested, and their structure and morphology were characterized. The calcination temperature has a great effect on the structure and properties of MS-SiO2/TiO2 composites. The composite particles calcined at 300 °C (MS-SiO2/TiO2-300) have low photocatalytic efficiency because they are aggregated seriously and the crystalline phase of TiO2 in MS-SiO2/TiO2-300 has not formed. While, the MS-SiO2/TiO2-500 composite particles showed a good separation state. The TiO2 particles on MS-SiO2 were single anatase phase, and its particle size was about 10–20 nm, exhibiting a well dispersion state. The degradation rate of MS-SiO2/TiO2-500 under 90 min ultraviolet irradiation was 92%, and the water contact angle was 10°, which was better than pure nano-TiO2. In MS-SiO2/TiO2, the reduction of TiO2 particles aggregation, improvement of dispersion and the presence of a single anatase phase were important factors for MS-SiO2 to exert a synergistic effect, which led to the enhancement of nano-TiO2 functional efficiency.