Preparation Of Rb Doped TiO₂ And Study Of Its Photocatalytic Mechanism

TiO₂ has a promising future in solving environmental pollution.Sol-gel technology has become one of the most widely-used methods to prepare TiO₂.However,it is reported that the industrialized application of this material prepared though sol-gel method have been limited due to some disadvantages.For example,the high recombination rate of photogenerated electrons and holes in titanium dioxide often leads to a low quantum yield;the morphology of material is not easy to control and it is difficult to manufacture TiO₂ on a large scale.In order to solve these problems,firstly,RbNO3 was added to improve the collosol and Rb doped TiO₂ has been synthesized.Then the spray drying technology has been adopted to optimize the sol-gel process.After that,the effect of calcination temperature and Rb doping on the properties of TiO₂ have been studied.TiO₂ doped with different concentration?0.1%?8%?of Rb were prepared by the sol-gel method.The relationship between the pH value,Rb doping concentration and the photocatalytic properties of TiO₂ has been explored.The result of photocatalytic experiments illustrate that the photocatalytic activity was greatly enhanced after doping Rb.When the doping concentration is 0.20%and pH value is 1.8,sample exhibits the best photcatalytic performance..The photocatalytic properties of spray-drying Rb-TiO₂ and normal Rb-TiO₂ has been compared.The results of photocatalytic experiments implied that spray drying technology can further improve the photocatalytic properties of TiO₂ by 30%.Besides,the optimum calcination temperature has been studied.The result of photocatalytic experiments show that the optimum calcination temperatures of sol-gel process and modified sol-gel process are 550? and 650?,relatively.The photocatalytic performance of TiO₂ has been greatly improved by multiple optimization,The sample which exhibits the best photocatalytic performance could degrade methylene blue with the fastest rate?90%within 25 min?.Finally,in order to explore the effect of Rb doping,Rb doped samples were characterized by X-ray diffraction?XRD?,transmission electron microscopy?TEM?,X-ray photoelectron spectroscopy?XPS?,Photoluminescence Spectroscopy?PL?and Ultraviolet-visible spectroscopy?UV-Vis?.It was confirmed by XRD and TEM that Rb doping could decrease the crystal size of TiO₂.The PL result of samples indicated that Rb doping could suppression the recombination of electron and hole.The result of XPS and UV-vis implied that Rb doping could shorten the band gap as well as extend the optical absorption of TiO₂ into the visible-light region.