物理化学学报 >> 2011, Vol. 27 >> Issue (06): 1487-1492.doi: 10.3866/PKU.WHXB20110621

催化和表面科学 上一篇    下一篇

不同pH值制备的TiO2和TiO2/SiO2催化剂结构、表面性质及光催化活性

仇伟, 任成军, 龚茂初, 侯云泽, 陈耀强   

  1. 四川大学化学学院, 教育部绿色化学重点实验室, 成都 610064
  • 收稿日期:2011-02-25 修回日期:2011-04-11 发布日期:2011-05-31
  • 通讯作者: 任成军, 陈耀强 E-mail:renchengjun@scu.edu.cn. nic7501@scu.edu.cn

Structure, Surface Properties and Photocatalytic Activity of TiO2 and TiO2/SiO2 Catalysts Prepared at Different pH Values

QIU Wei, REN Cheng-Jun, GONG Mao-Chu, HOU Yun-Ze, CHEN Yao-Qiang   

  1. Key Laboratory of Green Chemistry & Technology of the Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, P. R. China
  • Received:2011-02-25 Revised:2011-04-11 Published:2011-05-31
  • Contact: REN Cheng-Jun, CHEN Yao-Qiang E-mail:renchengjun@scu.edu.cn. nic7501@scu.edu.cn

摘要:

以TiOSO4和SiO2溶胶为原料, 采用沉淀法用氨水调节pH值制备TiO2和TiO2/SiO2催化剂. 制备的催化剂用X射线衍射(XRD), 扫描电镜(SEM), N2吸附(BET), 紫外-可见(UV-Vis)漫反射光谱, 程序升温脱附(NH3-TPD), 傅里叶变换红外(FT-IR)光谱技术分析. XRD谱图显示纯TiO2中锐钛型和金红石相共存, 且金红石相含量随pH值升高而增加. 但是, TiO2/SiO2催化剂只有锐钛型. 扫描电镜发现制备的催化剂呈类球形, 颗粒间相互交叠, 粒径在10-25 nm之间. TiO2和TiO2/SiO2光催化剂的比表面积随pH值升高略有增大. SiO2的添加会增大催化剂的比表面积. 程序升温脱附实验结果说明催化剂的表面酸量随pH值升高而增加. TiO2/SiO2的表面酸量比相同pH值制备的TiO2大. 红外光谱分析说明Si掺杂和高pH值有利于催化剂表面生成更多的羟基. TiO2和TiO2/SiO2光催化剂的催化活性随pH值升高而明显增强. TiO2/SiO2的光催化活性优于TiO2. TiO2/SiO2催化剂具有较好的耐久性.

关键词: pH, TiO2, SiO2掺杂, 微结构, 表面性质, 光催化

Abstract:

TiO2 and SiO2-doped TiO2 (TiO2/SiO2) catalysts were prepared using aqueous solutions containing a TiOSO4 and/or SiO2 sol in which NH3·H2O was used to adjust the pH value by a precipitation method. The as-synthesized photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), N2 adsorption (BET), UV-Vis diffuse reflectance spectroscopy, NH3 temperature programmed desorption (NH3-TPD), and Fourier transform infrared (FT-IR) spectroscopy. The XRD patterns showed that anatase and rutile coexisted in the as-prepared TiO2 and the rutile phase content increased with the increase in pH value. However, only anatase-TiO2 was observed in the TiO2/SiO2 catalysts. SEM revealed that the surface morphology of the particles was a sub-spherical shape and some agglomeration occurred on the surface while the particle size was mostly between 10 and 25 nm. Surface area measurements showed that the surface areas of the catalysts increased slightly with the increase in pH value. The incorporation of SiO2 increased the surface area. NH3-TPD analysis indicated that the amount of surface acid increased as the pH increased. The amount of surface acid on SiO2-doped TiO2 was higher than that on TiO2 when they were prepared at identical pH values. The addition of silica and the high pH value environment led to more surface hydroxyl groups on the catalysts as determined by FT-IR spectroscopy. The photocatalytic activity of the catalysts improved remarkably with the increase in pH value. The photocatalytic activity of SiO2-doped TiO2 is better than that of TiO2. The TiO2/SiO2 catalyst has better durability.

Key words: pH, TiO2, SiO2-doping, Microstructure, Surface property, Photocatalysis

MSC2000: 

  • O643