Preparation Of SnO₂/TiO₂ Nano-composite Thin Film And Its Photocatalytic Activity To MB

In the past 20 years, semiconductor materials (such as ZnO and TiO₂) applied as photocatalyst to treat the organic pollutants had been widespread Concerned. Many of the early studies show that such semiconductor photocatalytic materials under UV irradiation are able to degrade in almost all stable organic matter, including refractory organics. Due to the high chemical activity, stable chemical and optical properties, good heat and chemical resistance, non-toxic, cheap and a rich source of titanium dioxide, it is considered as the most promising one green catalyst. Compare with titania powder, supported TiO₂ film avoid difficult issues such as recycling, easy aggregation and so on. So solid nano thin film has become the focus of the study.In this thesis, nano-composite thin films SnO₂/TiO₂ were successfully prepared by liquid deposition. First, a smooth, uniform and transparent titania films had been deposited on surface of slides. The particles of TiO₂ are anatase crystal and the size of 4.31nm, film thickness is about 160nm.Various experimental conditions affected the properties of thin films had been investigated, and the optimal conditions for the film had been found out. Then uniform transparent SnO₂ films had been successfully produced on the slide by liquid phase deposition method, using KF·2H2O, SnCl4·5H2O and boric acid as raw materials. The grains of is rutile crystal, the average particle diameter is 2.88nm. The thickness of SnO₂ film is about 120 nm. From above, the SnO₂/TiO₂ composite film had been prepared by LPD. Composite film effectively reduce the size of particles and aggregation of particles and cracking phenomenon arised in heat treatment process. Finally, TiO₂ photocatalysts and SnO₂/TiO₂ composite photocatalysts used nickel screen as carriers had been produced.The experiments of degradation of methylene blue show that the photocatalyst is better than pure TiO₂ photocatalyst. The photocatalytic effect of the composite photocatalyst is improved because of the existence of SnO₂ which can restrain recombining of electron-hole pairs generated from TiO₂ under UV irradiation. The optimum relative content of SnO₂ in composite film is approximately 8%. The photocatalytic effect of photocatalyst used nickel screen as carriers is obviously superior to the slide as the carrier. Finally, the removal of MB is about 90%. The process of degradation accords with first-order reaction kinetics.