催化学报

催化学报 ›› 2014, Vol. 35 ›› Issue (2): 210-218.DOI: 10.1016/S1872-2067(12)60740-2

• 研究论文 • 上一篇    下一篇

X射线光电子能谱法研究UV254 nm光催化、O3强化UV254 nm光催化和真空紫外光催化降解甲醛中Pt-TiO2薄膜的表面性质

傅平丰a, 张彭义b   

  1. a 北京科技大学土木与环境工程学院, 北京100083;
    b 清华大学环境学院, 北京100084
  • 收稿日期:2013-09-28 修回日期:2013-10-23 出版日期:2014-01-16 发布日期:2014-01-17
  • 通讯作者: 张彭义
  • 基金资助:

    国家自然科学基金（21221004）；国家高技术研究发展计划（863计划，2012AA062701）；环境模拟与污染控制国家重点联合实验室专项基金（12K04ESPCT）.

Characterization of Pt-TiO2 film used in three formaldehyde photocatalytic degradation systems：UV254 nm, O3+UV254 nm and UV254+185 nm via X-ray photoelectron spectroscopy

Pingfeng Fua, Pengyi Zhangb   

  1. a School of Civil and Environment Engineering, University of Science and Technology Beijing, Beijing 100083, China;
    b State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
  • Received:2013-09-28 Revised:2013-10-23 Online:2014-01-16 Published:2014-01-17
  • Contact: Pengyi Zhang
  • Supported by:

    This work was supported by the National Natural Science Foundation of China (21221004), the National High Technology Research and Development Program of China (863 Program, 2012AA062701), and the Special Fund of State Key Joint Laboratory of Environment Simulation and Pollution Control (12K04ESPCT).

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摘要：

以Pt-TiO2为光催化剂，研究了气相甲醛分别在35 h连续UV254 nm光催化、O3强化UV254 nm（O3+UV254 nm）光催化和真空紫外（UV254+185 nm）光催化中的降解效率，考察了副产物O3的去除率，采用X射线光电子能谱（XPS）法分析Pt-TiO2在不同光催化前后Pt的电子态和累积有机产物，研究纳米Pt对甲醛降解和O3去除的强化机理. 连续光催化降解实验表明，以纳米Pt改性TiO2可以同时增强甲醛和O3的去除率，特别是O3的去除率可提高3.1-3.4倍. 对催化剂C 1s和O 1s峰分别经分峰拟合处理后，发现Pt-TiO2上累积的含羰基和羟基的有机物含量按以下顺序减少：UV254 nm光催化 > O3强化UV254 nm光催化 > 真空紫外光催化，而在连续35 h光催化降解过程中，催化剂的失活现象却按相反的方向变得越来越不明显. 负载的金属Pt在O3+UV254 nm和UV254+185nm光催化过程中被氧化成PtOads和Pt4+物种，而在UV254 nm光催化过程中金属Pt未被氧化，所以推测是气相中的O3和羟基自由基参与金属Pt的氧化过程. Pt-TiO2表面高价态的Pt氧化物种可作为光生电子捕获中心，强化光生载流子的分离过程，增强Pt-TiO2的光催化活性. Pt氧化物种可作为O3分解的活化中心，使Pt-TiO2对O3的分解效率远高于纯TiO2. 以XPS对比研究在三种不同光催化环境中Pt-TiO2表面性质，可以解释在UV254+185 nm光催化过程中纳米Pt对甲醛和O3同时去除的强化机理，并说明了催化剂不失活的内在原因.

关键词: 纳米铂, 真空紫外光, 光催化, 臭氧分解, 催化剂失活

Abstract:

Photocatalytic degradation of gaseous formaldehyde for 35 h was performed using Pt-TiO2 film in the following irradiation systems: UV254 nm, O3+UV254 nm, and UV254+185 nm. Concurrent improvements in formaldehyde degradation and O3 removal were achieved by modifying TiO2 with Pt nanoparticles, resulting in a 3.1-3.4-fold O3 elimination increase. X-ray photoelectron spectroscopy (XPS) of the Pt-TiO2 film was carried out to assess the electronic states of the Pt nanoparticles and accumulated organic species. The deconvoluted C 1s and O 1s XPS spectra revealed that the content of carbonyl and carboxyl groups on Pt-TiO2 and degree of catalyst deactivation in the systems studied decreased in the following order: UV254 nm > O3+UV254 nm > UV254+185 nm. Metallic Pt0 was oxidized to a mixture of PtOads and Pt4+ species under O3+UV254 nm and UV254+185 nm irradiation owing to the presence of O3 and hydroxyl radicals, but remained stable under UV254 nm irradiation. Pt species at higher oxidation states can act as electron trapping centers, and improve the photocatalytic activity of Pt-TiO2 and provide reactive sites for O3 decomposition under UV irradiation, resulting in a faster O3 removal rate than that displayed by TiO2. The XPS studies provided valuable information to elucidate the beneficial role of Pt species and the reduction of catalyst deactivation under UV254+185 nm irradiation.

Key words: Platinum nanoparticle, Vacuum ultraviolet, Photocatalysis, Ozone decomposition, Catalyst deactivation