Study Of SnO₂ Preparation And Its Photocatalytic Ability

In recent years, environmental pollution has become one serious problem that needs to be solved urgently. Due to its unique properties, semiconductor materials injecte new vitality for the degradation of pollutants. Especially in water pollution treatment, semiconductor materials can absorb sunlight to act as catalyst with high catalytic efficiency and can degrade almost all organic pollutants in high safety level. Thus, looking for a suitable photocatalysts with large surface area, high photocatalytic activity, wide range of response region to light, and a related suitable wastewater treatment technology which is economic, efficient and environmentally friendly have become very important.The purpose of this paper is to synthesis SnO₂ materials and composite materials which are modified by zinc oxide with high purity, small particle size, uniform morphology and good optical property by a simple strategy, and finally provide a theory for the practical application of SnO₂ materials in wastewater treatment field by the photocatalytic experiment. The research and results are following:?1? SnO₂ materials are prepared through sol-gel method at different conditions such as various precursor concentrations, calcination temperatures, surfactants and ethanol/water volume ratios.In the reaction, SnCl₄·5H₂O is used as precursor and ammonia solution is used as the source of precipitation. Besides, SnO₂/ZnO composite semiconductor materials are synthesized with different Sn⁴⁺ and Zn²⁺ precursor mole ratios by adding Zn?NO₃?₂·6H₂O.?2? The as-prepared samples are characterized by X-ray Diffraction ?XRD?, Scanning and Transmission Electron Microscopy ?SEM, TEM? and other optical characterization. The results illustrate that average sizes of the samples are between 5 nm and 17 nmn and SnO₂ particles have clear outline and show good distribution. SnO₂/ZnO composite photocatalysts exhibit a unique morphology by the addition of ZnO. The results of XRD illustrate that the characteristic diffraction peaks of composite materials are the most obvious when Sn ?4+? and Zn²⁺precursor mole ratios are 1:1. Then we analyze the particle nucleation and growth mechanism under different control parameters.?3? We investigate the degradability of SnO₂ and SnO₂/ZnO composite photocatalysts to organic dye molecules which methyl orange as the main target degradation, methylene blue and rhodamine B as the comparisons. When the ethanol/water volume ratio is 1:0, SnO₂ samples show the highest efficiency in the degradation of methyl orange. In the SDS surfactant reaction, SnO₂ samples'degradability is good. And SnO₂/ZnO composite materials exhibit good stability in reused experiments.?4? By fitting the experiment data, we discuss the dynamics of photocatalytic reaction and find out all photodegradation processes can be described as first-order kinetics. Finally, we study the mechanism of photocatalytic reaction which illustrate that SnO₂ and SnO₂/ZnO composite photocatalysts are kind of good photocatalysts for UV response.