物理化学学报 >> 2014, Vol. 30 >> Issue (5): 965-972.doi: 10.3866/PKU.WHXB201403171

催化和表面科学 上一篇    下一篇

低温静电自组装法制备贵金属修饰TiO2纳米结构薄膜及其增强的光催化性能

傅平丰1, 张彭义2   

  1. 1 北京科技大学土木与环境工程学院, 北京100083;
    2 清华大学环境学院, 环境模拟与污染控制国家重点联合实验室, 北京100084
  • 收稿日期:2014-02-10 修回日期:2014-03-17 发布日期:2014-04-25
  • 通讯作者: 张彭义 E-mail:zpy@tsinghua.edu.cn
  • 基金资助:

    国家高技术研究发展计划(863)(2012AA062701)和区域环境质量协同创新中心资助项目

Low-Temperature Electrostatic Self-Assembly of Noble Metals on TiO2 Nanostructured Films with Enhanced Photocatalytic Activity

FU Ping-Feng1, ZHANG Peng-Yi2   

  1. 1 School of Civil and Environment Engineering, University of Science and Technology Beijing, Beijing 100083, P. R. China;
    2 State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, P. R. China
  • Received:2014-02-10 Revised:2014-03-17 Published:2014-04-25
  • Contact: ZHANG Peng-Yi E-mail:zpy@tsinghua.edu.cn
  • Supported by:

    The project was supported by the National High Technology Research and Development Program of China (863) (2012AA062701) and Collaborative Innovation Center for Regional Environmental Quality, China.

摘要:

以碱-水热法在金属Ti 片上原位生长了TiO2纳米结构(纳米花和纳米线)薄膜,并采用低温静电自组装方法将超细贵金属(金、铂、钯)纳米颗粒均匀沉积于多孔TiO2薄膜上. 负载于Ti片上的贵金属/TiO2纳米结构薄膜具有一体化结构、多孔架构和高光催化活性. 超高分辨率场发射扫描电子显微镜(FESEM)直接观察表明贵金属纳米颗粒在TiO2表面分布均匀,且颗粒之间相互分离,金、铂、钯纳米颗粒的平均粒径分别约为4.0、2.0和10.0nm. 俄歇电子能谱(AES)纵深成分分析表明贵金属不仅沉积于薄膜表面,且大量分布于TiO2纳米结构薄膜内部,其深度超过580 nm. X射线光电子能谱(XPS)分析表明,经300 ℃下在空气中热处理后,纳米金仍保持金属态,纳米铂部分被氧化成PtOabs,而钯粒子则完全被氧化成氧化钯(PdO). 以低温静电自组装法沉积贵金属,贵金属负载量可通过调节组装时间与溶胶pH值来控制. 光催化降解甲基橙的结果表明,沉积的纳米金和铂能显著增加TiO2纳米结构薄膜的光催化活性,说明金和铂粒子可促进光生载流子的分离;但负载的PdO对TiO2薄膜的光催化性能增强几乎无作用.

关键词: 负载催化剂, 静电自组装, 贵金属纳米颗粒, TiO2纳米结构薄膜, 光催化活性

Abstract:

Photoactive TiO2 nanostructured films (i.e., nanoflowers and nanowires) have been directly synthesized on Ti sheets using an alkali-hydrothermal route. Ultrafine noble metals (i.e., Au, Pt, Pd) nanoparticles (NPs) were homogenously dispersed onto the TiO2 nanostructures using a facile low temperature electrostatic self-assembly approach. The resulting noble-metal/TiO2-nanostructured films supported on Ti sheets had an all-in-one structure with all of the virtues of a porous framework and enhanced photocatalytic activity. Ultra highresolution field-emission scanning electron microscopy (FESEM) revealed that the noble metal NPs were uniformly dispersed on the TiO2 surface with good physical separation properties. The average sizes of the loaded Au, Pt, and Pd NPs were approximately 4.0, 2.0, and 10.0 nm, respectively. Noble metal NPs were deposited not only on the film surface but also in the interior framework of the TiO2 films with a depth of more than 580 nm, as revealed by Auger electron spectroscopic (AES) in-depth profiling analysis. X-ray photoelectron spectroscopy (XPS) analysis revealed that the Pt and Pd NPs had been partially oxidized to PtOabs and immobicompletely oxidized to PdO, respectively, whereas the Au NPs remained in a metallic state after being annealed in air at 300 ℃. During the electrostatic self-assembly process, the loading of the noble metal can be adjusted by controlling the assembly time and the colloidal pH value. The degradation of aqueous methyl orange showed that the Au/TiO2 (or Pt/TiO2)-nanostructured films possessed remarkably enhanced photocatalytic activity compared with pure TiO2 films, and revealed that the metal NPs played a positive role in separating photogenerated hole-electron pairs. However, the deposited PdO species had no discernible impact on the activity of the TiO2 nanostructures.

Key words: Supported catalyst, Electrostatic self-assembly, Noble metal nanoparticle, TiO2 nanostructured film, Photocatalytic activity

MSC2000: 

  • O643