氟改性纳米二氧化钛的制备及光催化性能研究

发布时间：2018-05-26 03:15

本文选题：二氧化钛 + 氟改性　；参考：《四川农业大学》2015年硕士论文

【摘要】：环境问题日益严重,寻求一种经济高效的环境治理方法迫在眉睫。作为半导体光催化技术的代表——二氧化钛,常用于降解有机污染物,因为其具有比其他材料更稳定的化学性能、成本更低、更安全、并且无毒害作用。然而,锐钛矿型二氧化钛存在至今也很难完全解决的两个难点：一方面是不能有效利用自然界的太阳能,主要原因是由于二氧化钛光催化剂的有比较宽的禁带宽度,对可见光的利用率极低,通常只能被波长小于387 nm的紫外光激发,才能表现出其独特的光催化性能。众所周知,在自然界中,太阳光中只有微乎其微的紫外光,大概只有3%-4%。若能解决这个问题,那么Ti02光催化技术大规模的应用于实际则指日可待。第二方面主要是材料本身光催化性能的局限性。Ti02虽然能被紫外光高效的激发,但是在光催化过程中产生的光生电子和空穴的复合速率极高,导致能有效提高光催化效率的光量子的产率很低。本论文从提高Ti02在模拟太阳光下的光催化反应效率入手,采用溶胶-凝胶法与有氧、无氧煅烧方式的结合,通过引入氟离子修饰,以及借助碳离子的掺杂,研究了在制备过程中的溶液的pH、抑制剂的选择、反应温度的控制、掺杂氟源含量量、煅烧方式的选择、煅烧温度和煅烧时间的控制上对F-TiO2、CF-TiO2吸附、光催化活性的影响,以此确定各个因素的最优配比。然后通过各种材料表征方法,研究了材料的形貌、结构、元素组成、光学吸收特性等特征,并初步探讨了CF-TiO2各自优越性能的相关机制,通过一系列的实验和表征分析,获得了以下研究成果：(1)采用溶胶-凝胶法+有氧煅烧方式制备F-TiO2,通过对材料进行吸附、光催化性能研究得出制备的F-TiO2最佳条件：调节制备液A液的pH为5,选择无水乙酸作为过程的水解抑制剂,在室温25℃下反应,加入NaF掺杂量为n F/Ti=0.1,煅烧温度选取600℃,煅烧时间1h。(2) F-TiO2复合物中,Ti02纳米粒子分散较均匀,是典型的锐钛矿结构,晶粒尺寸16.89 nm。F原子替换Ti02表面的-OH化学吸附在Ti02表面,促进了Ti3+的产生。在导带下方形成氧空位能级,使禁带宽度变窄为2.75 eV,促进了其对可见光的吸收,并且降低了Ti02光生电子-空穴对的复合率,表现出优异的光催化性能。(3)采用溶胶-凝胶法+无氧煅烧方式制备CF-TiO2,通过对材料进行吸附、光催化性能研究得出制备的F-Ti02最佳条件：NaF掺杂量为n F/Ti=0.1,煅烧温度选取700℃。(4) CF-TiO2复合物中,TiO2纳米粒子呈现不规则的块状结构,颗粒分散性较好；具有混晶结构锐钛矿(97.08%)和金红石(2.92%)。具有多孔结构,比表面积大。C掺入品格,F原子替换表面的-OH化学吸附在TiO2表面,促使Ti3+的产生。C2p和O2p原子轨道杂化产生位于TiO2价带上方的碳杂化能级,氧空位在导带下方形成氧空位能级,这两个杂质能级使CF-TiO2禁带宽度变窄为2.50 eV。氟离子的引入抑制TiO2光生电子-空穴对的复合,CF-TiO2表现出优异的光催化性能。
[Abstract]:As a representative of semiconductor photocatalytic technology, titanium dioxide is often used to degrade organic pollutants, because they have more stable chemical properties than other materials, which are cheaper, safer and less toxic. However, anatase type two oxygen can be used. Titanium dioxide has two difficulties that have been difficult to solve completely. On the one hand, it is not effective to use the solar energy in nature. The main reason is that the titanium dioxide photocatalyst has a wide band gap, the utilization rate of visible light is very low, and it can only be excited by ultraviolet light less than 387 nm, in order to show its unique light. As we all know, in the nature, there is only a small ultraviolet light in the sun, and only 3%-4%. can solve this problem. Then Ti02 photocatalytic technology is applied in a large scale. The second aspect is mainly the limitation of the photocatalytic performance of the material itself, although it can be efficiently stimulated by ultraviolet light. However, the recombination rate of photoelectrons and holes produced in the photocatalytic process is very high, which leads to the low yield of the photons which can effectively improve the photocatalytic efficiency. This paper starts with the improvement of the photocatalytic reaction efficiency of Ti02 in the simulated solar light, by combining the sol-gel method with aerobic and anaerobic calcination, through the introduction of fluorine ions. Modification, and with the aid of carbon ion doping, the pH of the solution, the selection of the inhibitor, the control of the reaction temperature, the content of the doped fluorine source, the selection of the calcining mode, the influence of the calcining temperature and the calcining time on the F-TiO2, the CF-TiO2 adsorption and the photocatalytic activity were studied to determine the optimal ratio of each factor. Through a variety of material characterization methods, the morphology, structure, element composition and optical absorption characteristics of the material are studied, and the relevant mechanisms of CF-TiO2's superior properties are preliminarily discussed. Through a series of experiments and characterization analysis, the following research results are obtained: (1) the preparation of F-TiO2 by the sol-gel method and the oxygen calcination method is used. The best conditions for the preparation of F-TiO2 are obtained by the study of the photocatalytic properties. The pH of the prepared liquid A solution is 5, the hydrolytic inhibitor of the anhydrous acetic acid is selected as the hydrolysis inhibitor, the reaction at room temperature is 25 degrees C, the doping amount of NaF is n F/Ti=0.1, the calcining temperature is 600, and the calcining time 1h. (2) F-TiO2 complex, and the dispersion of the Ti02 nanoparticles is more dispersed. Even, it is a typical anatase structure. The -OH chemically adsorbed on the surface of the Ti02 surface with grain size of 16.89 nm.F atoms adsorbs on the surface of the Ti02 and promotes the production of Ti3+. The oxygen vacancy level is formed under the guide band, and the band gap is narrowed to 2.75 eV, which promotes the absorption of the visible light and reduces the recombination rate of the Ti02 photoelectron hole pair. Excellent photocatalytic properties. (3) CF-TiO2 was prepared by sol-gel and anaerobic calcination. Through the adsorption of materials, the best conditions for the preparation of F-Ti02 were obtained by the study of photocatalytic properties: the amount of NaF doping was n F/Ti=0.1, the calcination temperature was selected at 700. (4) CF-TiO2 complex, TiO2 nanoparticles presented irregular lump structure, particles The dispersivity is good, with mixed crystal structure of anatase (97.08%) and rutile (2.92%). It has a porous structure, a larger.C than the surface area, and the -OH chemical adsorption on the surface of the F atom is adsorbed on the surface of the TiO2, causing Ti3+ to produce.C2p and O2p atom orbitals to produce the carbon hybrid energy level above the TiO2 valence band, and the oxygen vacancy is formed under the guide band. Oxygen vacancy level, these two impurity levels make the band gap of CF-TiO2 narrow to 2.50 eV. fluorine ions to inhibit the recombination of TiO2 photoelectron hole pair, and CF-TiO2 shows excellent photocatalytic performance.
【学位授予单位】：四川农业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ134.11;O643.36

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