【作者】 陈亮；

【导师】 张守臣；

【作者基本信息】 大连理工大学 ， 化学工艺， 2009， 硕士

【摘要】 二氧化钛（TiO₂）以其价格低廉、无毒、化学性质稳定和催化效率高等优点,在光电转化和光催化领域倍受关注。由于TiO₂的禁带宽度较大,只能被紫外光激发,且光生电子和空穴易复合,因此限制了其在光催化领域的广泛应用。因此,通过多种手段对TiO₂催化剂进行改性,提高TiO₂的光催化效率是将这一技术推向实际应用的重要环节。二氧化钛的改性已被证明是提高光催化活性的简单有效的途径。本文使用不同的方法对TiO₂光催化剂进行改性,采用溶胶-凝胶法合成了TiO₂,通过高温锻烧处理的合成路线,找到形成TiO₂锐钛矿相和金红石相混晶的最佳的温度;采用球磨法,以六次甲基四胺（HMT）为氮源掺杂TiO₂;采用光催化还原法制备Ag掺杂TiO₂。本文还选择了不同掺杂金属制成具有钙钛矿结构（ABO₃）的钛酸盐;再通过掺杂其他金属离子,改变其A位和B位离子,并寻找最佳的掺杂量。详细研究了反应条件对产物的晶相,晶化程度,光催化活性等的影响。使用XRD、TG、SEM等手段对催化剂结构和性能进行了表征,并研究了它们对亚甲基兰的光催化降解性能。（1）用溶胶-凝胶法合成TiO₂煅烧温度有一个最佳值550℃,可形成锐钛矿和金红石两种晶相的混晶,煅烧温度过低或过高催化剂的活性都有所下降,不利于光催化反应。（2）在日光和紫外光下,球磨法制备的N掺杂TiO₂光催化剂较未掺杂TiO₂混晶的光催化效率有很大增强,10%的N掺杂量为最佳。（3）在日光下,光催化还原法制备的Ag掺杂TiO₂光催化剂较未掺杂TiO₂混晶的光催化效率提高不大,但在紫外光下,却有很大的提高。（4）用溶胶-凝胶法合成的SrTiO₃、NiTiO₃、Ce₂TiO₅、La₂TiO₅、CoTiO₃、ZnTiO₃六类钙钛矿结构光催化剂,除了CoTiO₃以外都有比较好的光催化性能,尤其以SrTiO₃最佳。（5）用溶胶-凝胶法合成的Zr:SrTiO₃与Ba:SrTiO₃光催化剂中,Zr⁴⁺与Ba²⁺的掺杂可以有效提高催化剂的光催化效率。但它有一个最佳掺杂量,高于或低于这个最佳掺杂量,催化剂的催化性能有所降低。在本实验中,8%Zr:SrTiO₃与6%Ba:SrTiO₃最佳。更多还原

【Abstract】 Titanium dioxide,a photocatalyst,has received a great deal of attention owing to its advantages such as high chemical stability,non-toxicity and low cost etc.But only under UV, TiO₂ can be excited because of its wide band gap.And the electrons from the valence band to the conduction band and the holes in the valence band are easy to recombine,which restricts the application of TiO₂.Thus Photocatalyst with higher activity and efficiency is an essential for its application in large scale.Doped TiO₂ has been proved to be a simple and efficient technic to improve the photoactivity.In this paper,there are different methods to improve the photocatalyst of TiO₂,including high-temperature calcinations based on the sol-gel,and search proper temperature of the formation for TiO₂ mixed crystal.And then,choose HMT to synthesize N:TiO₂ using ball-milling.By the way,the photocatalyst of Ag/TiO₂ is prepared by a simple chemical reduction method.At the same time,synthesize the Titanate by doped various metals.After that modify A-ion and B-ion with other metals,and discover the best amount of dopant.The impact of reaction condition on crystal phase,crystallization degree,and photocatalytic activities of methylene blue degradation are particularly investigated.Finally,the samples were characterized by Differential Thermal Analysis and Thermal Gravimetric analysis（DTA-TG）、X-ray diffraction（XRD） and Scanning Electron Microscopy（SEM）.The conclusions of the paper show:a.550℃is the best calcination temperature of TiO₂ in sol-gel,the mixed crystal of TiO₂ is formed.The experiment also shows that too high or low temperature of the calcinations is harmful to the photocatalytic activity.b.Both in sunlight and UV-light,the photocatalysis of N:TiO₂ using bail-milling method is much better than the mixed crystal of TiO₂ and the best amount of dopant in N: TiO₂ is 10%.c.In UVlight,the photocatalysis of Ag/TiO₂ prepared by a simple chemical reduction method is much better than the mixed crystal of TiO₂,but not good in the sunlight.The best amount of dopant in Ag/TiO₂ is 1%.d.SrTiO₃、NiTiO₃、Ce₂TiO₅、La₂TiO₅、CoTiO₃ and ZnTiO₃ are synthesized by sol-gel under 550℃.Among these catalysts,the photoeatalytic activity of CoTiO₃ is worse than others,and SrTiO₃ is the best. e.Doping Zr⁴⁺ and Ba²⁺ for SrTiO₃ by sol-gel can greatly improve efficiency of photocatalysis.But there is a best amount of dopant.The research indicates that with more dopant,the photoeatalysis is worse.The best amount of dopant in Zr:SrTiO₃ and Ba.SrTiO₃ are 8%and 6%.更多还原