Low-temperature Preparation And Properties Of TiO₂/SnO₂ Composite Sols And Composite Films

The research of TiO₂ has been attented extensively since Fujishima and Honda published a thesis named "Electrochemical Photolysis of Water at a Semiconductor Electrode" in Nature. At present, TiO₂ has been employed in the photocatalytic decontamination treatment of polluted water and air. However, the fast recombination rate of photogenerated electron/hole pairs hinders the commer-cialization of this technology. Coupling of SnO₂ and TiO₂ as one of the effective method to lower electron/hole pairs recombination has been extensively studied. Traditional sol-gel method to prepare TiO₂/SnO₂ composite materials need heat treatment that makes the preparation process complexity, and limit its utilization on the non-heat-resistant based material and the based materials that hard to be heat-treated. Based on the actuality, the low-temperature preparation and properties of TiO₂/SnO₂ composite sols and composite films were proposed in this paper.Sol-Gel method was applied in the preparation of TiO₂/SnO₂ composite film and composite sol at low temperature in this paper. In the research, the TiO₂ sol was made with Ti(OC₄H₉)₄ as precursor, ethanol as impregnant, HCl as catalyzer; and the SnO₂ sol was prepared with SnCl₄·5H₂O as precursor, ammonia as precipitator, polyethylene glycol as dispersant, then based on the sols, the TiO₂/SnO₂ composite film and composite sol was made . After which , the crystal structure and the photocatalytic efficiency of the samples completed was tested through XRD, SEM, TEM, PL, Volume analyse, UV-Vis. The research results were shown below:Firstly, crystals was found in all the samples, cause of which, all the samples have the ability of photocatalytic decomposition.Secondly, the terrace composite films of TiO₂/SnO₂ showed a better capability than the pure TiO₂ film in Rhodamine B decomposition and when the film of SnO₂ layer reached 3, the apparent decomposition velocity is 3.67 times than the pure TiO₂ film almost reached the peak.Thirdly, the photocatalytic decomposition activity of the mixed sols showed no obvious increase than the pure TiO₂ sol. When the mol ratio value of n(Sn):n(Ti) reached 5%, the photocatalytic decomposition activity began to decrease. The test results showed that: the decomposition capability of mixed composite films wasimproved than the pure TiO₂ film, and it reached the best when the mol ratio value of n(Sn):n(Ti) at 2%.Fourthly, the core-coat TiO₂/SnO₂ composite sol and composite films showed a better decomposition capability than the pure TiO₂ sol and film, and it also showed a good photocatalytic activity after be excitated by the visible light.