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1、南京航空航天大学 硕士学位论文 有序介孔TiO2薄膜的制备及其光电化学性能 姓名：吴士超 申请学位级别：硕士 专业：应用化学 指导教师：何建平 2011-03 南京航空航天大学硕士学位论文 I 摘 要 本论文以制备新型的光辅助高效燃料电池催化剂载体为主线，分别对介孔二氧化钛薄膜、 介孔SiO2/TiO2复合薄膜和介孔SiO2-WO3-TiO2三元复合薄膜的制备和作为载体的甲醇光电催化 氧化性能进行了研究。 以TiCl4为钛源、三嵌段共聚物F127为模板剂，无水乙醇和水为混合溶剂，采用旋涂法在导 电玻璃（FTO）表面制备介孔二氧化钛薄膜，系统地研究了热处理温度对其结构、形貌和性能 的影响。XRD
2、、TEM和FE-SEM结果表明，经350和400热处理的二氧化钛薄膜的结构呈现二 维六方有序介孔孔道排列。热处理温度达到450时，由于二氧化钛的结晶颗粒不断长大，破坏 了介孔结构的有序性，薄膜表面杂乱无章。采用脉冲恒电压沉积的方法，将催化剂Pt负载于薄 膜表面，研究了Pt的负载量对其光电催化性能的影响。适量的Pt负载在介孔二氧化钛薄膜的表 面，有效提高了二氧化钛的光效应，表现出较好的甲醇光电催化氧化性能。同时，将介孔二氧 化钛薄膜的甲醇光电催化性能与没有介孔有序结构的二氧化钛薄膜作对比，发现有序介孔结构 对其性能的提升有显著作用。 由于具有较好的有序介孔结构和二氧化钛结晶度， 经过400热处
3、理后的介孔二氧化钛薄膜为Pt催化剂载体时表现出相对较好的甲醇光电催化氧化性能。尝试在 介孔二氧化钛前躯体溶胶中引入氯铂酸，原位制备含Pt的介孔二氧化钛薄膜，当Pt掺杂量为3% 时，薄膜既可以保持较好的有序介孔结构又具有较高的甲醇光电催化氧化性能，尤其是以非均 匀掺杂Pt的方式制备的薄膜。 为了提高薄膜的热稳定性，在介孔二氧化钛前躯体溶胶中引入正硅酸乙酯，制备介孔 SiO2/TiO2复合薄膜。由于二氧化硅骨架的加入，限制了二氧化钛晶粒的增长，经过 450、500 和 550热处理的复合薄膜仍能保持较好的有序介孔结构。实验发现，当二氧化硅掺杂量为 5% 时，较少的二氧化硅掺杂量对二氧化钛颗粒增长限
4、制作用有限，复合薄膜在 450热处理后有 序介孔结构较差。掺杂量达到 7.5%时，复合薄膜即使经过 550的高温热处理也可以保持高度 有序的介孔结构。在二氧化硅掺杂量为 7.5%，经过 500热处理后，介孔 SiO2/TiO2复合薄膜 表现出的甲醇光电催化氧化性能相对于没有掺杂 SiO2的介孔二氧化钛薄膜提高了约 17.4%。 进一步采用半导体复合的方式提高二氧化钛的性能。在介孔二氧化钛前躯体溶胶中添加硅 钨酸，热处理后得到介孔 SiO2-WO3-TiO2三元复合薄膜。研究掺杂含量对复合薄膜结构和性能 的影响。实验发现，硅钨酸的引入降低了二氧化钛的晶相转换温度，400热处理后，部分二氧 化钛转
5、化为金红石相。 硅钨酸掺杂含量为 0.5%时， 介孔三元复合薄膜具有较好的有序介孔结构， 有序介孔 TiO2薄膜的制备及其光电化学性能 II 且金红石相二氧化钛和锐钛矿相二氧化钛的混合比例最佳，对甲醇的光电催化氧化性能最好。 实验过程中发现，由于 WO3的电子存储能力，复合薄膜表现出一定的能量存储效应。当去除光 照条件后，储存在 WO3中的电子会缓慢释放，延续甲醇光电催化氧化的能力。 关键词关键词： 介孔 TiO2薄膜，SiO2/TiO2，SiO2-WO3-TiO2，光电催化氧化 南京航空航天大学硕士学位论文 III ABSTRACT The highly ordered mesoporous
6、 TiO2 film used as the novel photo-assisted catalyst support material of DMFC was prepared on the FTO with TiCl4 as the titanium source, F127 as the template, CH3CH2OH and H2O as the mixed solvent through spin-coating. In order to promote its performance, the SiO2 and H4SiW12O40 were selected to mix
7、 with the mesoporous TiO2 film. Their mesoporous structure and performance of photoelectrochemical catalysis were studied systematically. The TiO2 film with the ordered mesochannols parallel to the substrate was successfully synthesized by a rapid and simple EISA method. XRD, TEM and FE-SEM results
8、showed that, the TiO2 films after heat treatment at 350 and 400 had well-ordered 2D-hexagonal mesostructure of the P6mm space group with high-quality and large-domain regularity. However, the ordered mesostructure was destroyed due to the continuous growth of the TiO2 particle size after heat treatm
9、ent at 450 . Pt was electrodeposited on the mesoporous TiO2 films by potentiostatic pulse electrodeposition method. The TiO2 film with optimal Pt content showed high performance of photoelectrochemical oxide for methanol because of the special interactions between Pt and TiO2. The mesoporous TiO2 fi
10、lm after heat treatment at 400 possessing regular mesostructure and sufficient crystallinity suggested the better performance of photoelectrochemical oxide for methanol compared to the TiO2 film with poor crystallinity after heat treatment at 350 and the TiO2 film with disordered structure after hea
11、t treatment at 450 . The mesoporous Pt/TiO2 film in situ prepared can reach the better catalytic activity by adjusting the Pt content and controlling the film arrange style. In order to increase the thermal stability of the film, the mesoporous SiO2/TiO2 composite film was prepared by adding TEOS to
12、 the as-prepared TiO2 solution. The rigid framework of SiO2 can effectively promote the thermal stability of the film and manage to make the TiO2 film hold the ordered mesostructure even after heat treatment as high as 550 . However, the mesoporous SiO2/TiO2 composite film after heat treatment at 50
13、0 showed the better photoelectrochemical catalytic activity because the electrical conductivity of FTO decreased dramatically after heat treatment as high as 550 . In addition, it was found that, the SiO2 content affected the structure and peroformance of the mesoporous SiO2/TiO2 composite film. Wit
14、h the SiO2 content 7.5%, the mesoporous SiO2/TiO2 composite film exhibited excellent catalytic activity of methanol. Composited semiconductor was further employed to improve the photocatalytic activity of TiO2 by introducing WO3. The mesoporous SiO2-WO3-TiO2 composite films with different WO3 conten
15、ts 有序介孔 TiO2薄膜的制备及其光电化学性能 IV were prepared and studied about their mesostructure and photoelectrochemical activity of methanol. It was found from the experiment that, the introduction of WO3 reduced the titania phase transformation temperature and a part of anatase had transformed into rutile. With
16、the doped WO3 content of 0.5%, the mesoporous composite film had well-ordered mesostructure and the best mixed ratio of anatase and rutile, indicating the optimal performance of photoelectrochemical oxide for methanol. At the same time, due to the electronic storage of WO3, even without the UV illumination, the mesoporous SiO2-WO3-TiO2 composite film still showed photoelectrochemical activity by releasing the stored enectrons in WO3. KeyWords： mesoporous TiO2 film, SiO2/TiO2,
