二氧化钛可控晶面制备光催化剂的理论及实验研究
发布时间：2018-08-05 09:25
【摘要】：近年来,二氧化钛(TiO_2)以其成本低廉、无二次污染、极强氧化还原能力、耐光学和化学腐蚀性及性质稳定,成为整个半导体光催化研究领域的热点。尽管,TiO_2在光催化研究领域已取得了较多理论和实验研究成果,但TiO_2光催化方法依然未能取得大规模应用,制约其应用主要瓶颈在于:①TiO_2光催化量子效率不够高;②TiO_2对可见光的利用率低,需要外加能耗。目前传统合成方法对锐钛矿TiO_2晶面的暴露比例和生长趋势可控性不强,同时,生成的晶体排布无序,粒径大小不一,随机性大,不能充分利用TiO_2(001)晶面的光催化性能。原因在于TiO_2各个晶面暴露的选择性生长机理尚不清楚。外加,传统合成工艺自身参数的不可控性,以至于对TiO_2晶面的暴露比例及生长趋势得不到充分的控制,也就限制了 TiO_2光催化性能的最优化利用。因此,探明TiO_2晶面生长机理,探索可控、可调的晶面暴露的制备技术与方法,对于提高TiO_2光催化性能有较大的研究意义。本文首先采用理论计算对TiO_2光催化面进行理论研究,通过表面能、吸附能、态密度和能带等数据获得Tio2晶面生长的理论机理;再结合实验,采用原子层沉积技术制备TiO_2光催化剂,并通过控制反应前驱体脉冲的循环周期数和温度来控制TiO_2成膜结构和形貌;利用XRD、SEM、TEM对TiO_2薄膜进行表征,以期获得制备可控、高效的光降解催化剂的机理。通过理论计算发现:在TiO_2(001)、(010)和(101)三个晶面中,(001)晶面表面能为1.09 J/m2具有最好的光催化活性;再以钛酸钡(BTO)晶体作为基底,构建TiO_2-BTO生长模型,诱导TiO_2不同晶面生长,(001)晶面以结合能为-1.27eV,键长分别为1.916A和1.932A,成为生长最为稳定的模型。同时发现TiO_2(001)晶面不同层数的生长对催化降解有一定影响利用原子层沉积方法制备TiO_2光催化剂,通过对设备参数的不断调试得出最佳参数,并在以钛酸钡为基体的石英玻璃片上镀TiO_2薄膜,制备TiO_2光催化剂。采用XRD、SEM、TEM对制备的样品进行表征分析,结果证明利用原子层沉积技术成功的将TiO_2以膜的形式镀在基体表面,镀膜厚度随沉积圈数的增加而增加。将制备的TiO_2光催化剂,对一定浓度的甲基橙进行光催化降解实验,结果证明利用ALD技术制备的TiO_2光催化剂,能够对有机物污染物进行更好的催化降解。
[Abstract]:In recent years, titanium dioxide (TiO_2) has become a hotspot in the field of semiconductor photocatalysis because of its low cost, no secondary pollution, strong redox ability, optical and chemical corrosion resistance and stable properties. Although TiO2 has made many theoretical and experimental achievements in the field of photocatalytic research, the TiO_2 photocatalytic method has not been applied on a large scale, and the main bottleneck of its application is that the quantum efficiency of photocatalysis is not high enough. The utilization rate of visible light by 2TiO_2 is low, which requires additional energy consumption. At present, the exposure ratio and growth trend of anatase TiO_2 crystal surface are not controlled by traditional synthesis methods. At the same time, the resulting crystals are disordered, with different particle size and large randomness, which can not make full use of the photocatalytic performance of TiO_2 (001) crystal plane. The reason is that the selective growth mechanism of TiO_2 exposed to various crystal faces is not clear. In addition, the uncontrollability of the parameters of the traditional synthesis process makes it impossible to control the exposure ratio and growth trend of the TiO_2 crystal plane, which limits the optimum utilization of the photocatalytic properties of TiO_2. Therefore, it is of great significance to investigate the growth mechanism of TiO_2 crystal plane and to explore the preparation techniques and methods of controllable and adjustable exposure of crystal plane for improving the photocatalytic performance of TiO_2. In this paper, the theoretical mechanism of the growth of TiO_2 photocatalytic surface is obtained by using the data of surface energy, adsorption energy, density of state and energy band. TiO_2 photocatalyst was prepared by atomic layer deposition technique, and the structure and morphology of TiO_2 film were controlled by controlling the cycle period and temperature of the reaction precursor pulse, and the structure and morphology of TiO_2 film were characterized by XRDX SEMTEM in order to obtain controllable preparation of TiO_2 film. Mechanism of highly efficient photodegradation catalysts. The theoretical calculation shows that the surface energy of (001) crystal surface is 1.09 J/m2 with the best photocatalytic activity in the TiO_2 (001), (010) and (101) faces, and the TiO_2-BTO growth model is constructed by using barium titanate (BTO) crystal as the substrate. (001) the binding energy of (001) faces is -1.27 EV, and the bond lengths are 1.916A and 1.932A, respectively, which are the most stable growth models. At the same time, it was found that the growth of different layers of TiO_2 (001) crystal plane had a certain influence on the catalytic degradation. The TiO_2 photocatalyst was prepared by atomic layer deposition, and the optimum parameters were obtained by adjusting the parameters of the equipment. TiO_2 films were deposited on quartz glass substrates of barium titanate to prepare TiO_2 photocatalyst. The TiO_2 was successfully deposited on the substrate by atomic layer deposition, and the thickness of the film increased with the increase of the number of coils. The photocatalytic degradation experiments of methyl orange with certain concentration of TiO_2 photocatalyst were carried out. The results showed that the TiO_2 photocatalyst prepared by ALD technology could better catalyze the degradation of organic pollutants.
【学位授予单位】：重庆三峡学院
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36
本文编号：2165359
[Abstract]:In recent years, titanium dioxide (TiO_2) has become a hotspot in the field of semiconductor photocatalysis because of its low cost, no secondary pollution, strong redox ability, optical and chemical corrosion resistance and stable properties. Although TiO2 has made many theoretical and experimental achievements in the field of photocatalytic research, the TiO_2 photocatalytic method has not been applied on a large scale, and the main bottleneck of its application is that the quantum efficiency of photocatalysis is not high enough. The utilization rate of visible light by 2TiO_2 is low, which requires additional energy consumption. At present, the exposure ratio and growth trend of anatase TiO_2 crystal surface are not controlled by traditional synthesis methods. At the same time, the resulting crystals are disordered, with different particle size and large randomness, which can not make full use of the photocatalytic performance of TiO_2 (001) crystal plane. The reason is that the selective growth mechanism of TiO_2 exposed to various crystal faces is not clear. In addition, the uncontrollability of the parameters of the traditional synthesis process makes it impossible to control the exposure ratio and growth trend of the TiO_2 crystal plane, which limits the optimum utilization of the photocatalytic properties of TiO_2. Therefore, it is of great significance to investigate the growth mechanism of TiO_2 crystal plane and to explore the preparation techniques and methods of controllable and adjustable exposure of crystal plane for improving the photocatalytic performance of TiO_2. In this paper, the theoretical mechanism of the growth of TiO_2 photocatalytic surface is obtained by using the data of surface energy, adsorption energy, density of state and energy band. TiO_2 photocatalyst was prepared by atomic layer deposition technique, and the structure and morphology of TiO_2 film were controlled by controlling the cycle period and temperature of the reaction precursor pulse, and the structure and morphology of TiO_2 film were characterized by XRDX SEMTEM in order to obtain controllable preparation of TiO_2 film. Mechanism of highly efficient photodegradation catalysts. The theoretical calculation shows that the surface energy of (001) crystal surface is 1.09 J/m2 with the best photocatalytic activity in the TiO_2 (001), (010) and (101) faces, and the TiO_2-BTO growth model is constructed by using barium titanate (BTO) crystal as the substrate. (001) the binding energy of (001) faces is -1.27 EV, and the bond lengths are 1.916A and 1.932A, respectively, which are the most stable growth models. At the same time, it was found that the growth of different layers of TiO_2 (001) crystal plane had a certain influence on the catalytic degradation. The TiO_2 photocatalyst was prepared by atomic layer deposition, and the optimum parameters were obtained by adjusting the parameters of the equipment. TiO_2 films were deposited on quartz glass substrates of barium titanate to prepare TiO_2 photocatalyst. The TiO_2 was successfully deposited on the substrate by atomic layer deposition, and the thickness of the film increased with the increase of the number of coils. The photocatalytic degradation experiments of methyl orange with certain concentration of TiO_2 photocatalyst were carried out. The results showed that the TiO_2 photocatalyst prepared by ALD technology could better catalyze the degradation of organic pollutants.
【学位授予单位】：重庆三峡学院
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36
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