单晶钛基光催化剂的熔盐法制备及其改性研究

发布时间：2018-05-20 21:54

  本文选题：熔盐法 + 光催化　； 参考：《中国地质大学(北京)》2017年硕士论文

【摘要】：钛基光催化剂拥有无毒无污染、稳定的物化性质和低成本等优点,作为高效的半导体光催化剂在光催化方面获得广泛的应用。但钛基光催化剂的宽带隙和较高的电子空穴复合率阻碍了它的发展,近年来对其光催化能力的提高成为人们研究的热点。所以,本论文主要集中于对钛基光催化剂材料性能和制备方法的改进。本论文以钛基光催化剂为主要研究对象,采用熔盐法在煅烧过程中引入硝酸盐制备钛酸盐及氮掺杂、氮氟共掺杂的TiO_2,通过熔盐体系降低制备样品的煅烧温度,提高样品的光催化活性,研究其对样品结构组成、能带宽度、光催化机制的影响。通过对样品的组成分析、形貌结构及光学性能进行分析,结果表明:(1)采用熔盐法制备的N掺杂单晶TiO_2催化剂在可见光照射下对亚甲基蓝(MB)具有很高的光催化降解效果。氮掺杂使TiO_2的能带宽度降低,促进催化剂对光的吸收向可见光范围的拓展;熔盐体系促进TiO_2单晶结构的形成、比表面积的增大以及表面NO物种的增多,有利于提高样品的光催化能力。(2)采用熔盐法制备的氮氟共掺杂的纳米立方形单晶TiO_2催化剂具有较高的(001)面暴露率,有利于光催化性能的提高。氮氟共掺杂TiO_2的禁带宽度较小,使TiO_2对光的吸收向可见光方向迁移,并且其表面吸附了NO和氟离子,有利于提高样品的光催化能力。(3)采用熔盐法制备的钛酸盐催化剂随着煅烧温度的升高,其比表面积呈减小的趋势,而禁带宽度呈先增大后减小的趋势,于600℃下制得样品的禁带宽度最小,700℃的禁带宽度最大。于650℃下制备出具有层状结构的钛酸盐纳米带,其具有较好的光催化效果。
[Abstract]:Titanium based photocatalyst has many advantages, such as non-toxic and pollution-free, stable physicochemical properties and low cost. As a highly effective semiconductor photocatalyst, it has been widely used in photocatalysis. However, the wide band gap and high electron hole recombination rate of titanium-based photocatalyst hinder its development. In recent years, the improvement of its photocatalytic ability has become a hot research topic. Therefore, this paper mainly focuses on the improvement of the properties and preparation methods of titanium based photocatalyst materials. In this thesis, titanium based photocatalyst was used as the main research object. Titanate and nitrogen-doped TiO2 were prepared by introducing nitrate into the calcination process by molten salt method. The calcination temperature of the prepared samples was reduced by melting salt system. The influence of the photocatalytic activity on the structure, band width and photocatalytic mechanism of the samples was studied. The composition, morphology and optical properties of the samples were analyzed. The results show that the N-doped single crystal TiO_2 catalyst prepared by molten salt method has a high photocatalytic degradation effect on methylene blue MBs under visible light irradiation. Nitrogen doping reduced the band width of TiO_2, promoted the light absorption of catalyst to visible light, and promoted the formation of TiO_2 single crystal structure, the increase of specific surface area and the increase of no species on the surface. It is advantageous to improve the photocatalytic ability of the sample. (2) the nitrofluorine-co-doped nano-square single crystal TiO_2 catalyst prepared by molten salt method has a high surface exposure rate, and is beneficial to the improvement of photocatalytic performance. The band gap of nitrofluorine co-doped TiO_2 is small, which makes the absorption of TiO_2 light migrate to visible light, and no and fluoride ions are adsorbed on the surface of TiO_2. The specific surface area of titanate catalyst prepared by molten salt method decreased with the increase of calcination temperature, while the width of forbidden band increased first and then decreased. The band-gap of the sample prepared at 600 鈩，

本文编号：1916368