超临界流体干燥法制备纳米TiO2-SnO2-SiO2复合光催化剂及其光催化性能研究

半导体多相光催化法作为一种污染治理新技术越来越受到人们的重视,在所使用的半导体光催化剂中,TiO2以无毒,催化活性高,价廉,无污染等特点,成为最具有前途的绿色环保型催化剂之一1],但其自身具有局限性,如禁带宽度大,需在近紫外光下才能激发产生电子空穴对,对太阳光的利用率仅

Photocatalytic Properties of TiO2-SnO2-SiO2 Nano-composite Photocatalyst Prepared by Supercritical Fluid Drying

TiO₂-SnO₂-SiO₂ nanocomposite photocatalysts were prepared with Na₂SiO₃·9H₂O, SnCl₄·5H₂O and TiCl₄ as precursors by chemistry coating processes and supercritical fluid drying (SCFD) method. Characterizations with XRD, TEM, NMR and FTIR showed that in addition to anatase type TiO₂, a new active phase(Ti,Sn)O₂ was also formed in the range of the studied doping concentration, The catalytic activity was evaluated by photocatalytic degradation of phenol as model reaction. SiO₂ remained amphorous at all samples. It could prevent from growth of the size of nanopaticle and transformation from anatase to rutile. Compared with pure TiO₂, or TiO₂-SnO₂ catalyst prepared by Sol-gel method, Nano-composite photo-catalyst showed significant improvement in catalytic activity, the photo-catalytic degradation rate of phenol in 7 h reached 88.7%. Application of the composite catalysts for the photocatalytic decomposition of phenol not only gave the same activity relative to pure ultrafine TiO₂, but also reduced cost. The experimental results also proved that the thermal stability of TiO₂ was greatly enhanced after mixing with small amount of SiO₂. The optimized doping of SiO₂ was 20.3%. The photo-catalyst prepared by SCFD combination technology was characterized with smaller particle size, larger surface area and higher activity.