4. In Situ Studies on Photocatalytic Materials, Surface Intermediates, and Reaction Mechanisms

  1. Karen Wilson4 and
  2. Adam F. Lee5,6
  1. Hendrik Kosslick1,
  2. Vu Anh Tuan2 and
  3. Detlef W. Bahnemann3

Published Online: 13 SEP 2013

DOI: 10.1002/9783527658985.ch4

Heterogeneous Catalysts for Clean Technology: Spectroscopy, Design, and Monitoring

Heterogeneous Catalysts for Clean Technology: Spectroscopy, Design, and Monitoring

How to Cite

Kosslick, H., Tuan, V. A. and Bahnemann, D. W. (2013) In Situ Studies on Photocatalytic Materials, Surface Intermediates, and Reaction Mechanisms, in Heterogeneous Catalysts for Clean Technology: Spectroscopy, Design, and Monitoring (eds K. Wilson and A. F. Lee), Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, Germany. doi: 10.1002/9783527658985.ch4

Editor Information

  1. 4

    Aston University, European Bioenergy Research Institute, School of Engineering and Applied Science, Birmingham, B4 7ET, United Kingdom

  2. 5

    University of Warwick, Department of Chemistry, Coventry, CV4 7AL, United Kingdom

  3. 6

    Monash University, School of Chemistry, Victoria 3800, Australia

Author Information

  1. 1

    University of Rostock, Institute of Chemistry and Leibniz Institute for Catalysis, Department of Inorganic Chemistry and Department of Material Design, Albert Einstein-Str. 3a, 18059, Rostock, Germany

  2. 2

    Vietnam Academy of Science and Technology (VAST), Institute of Chemistry, Department of Inorganic Chemistry and Physical Chemistry, 18 Hoang Quoc Viet, Cao Giay, Hanoi, Vietnam

  3. 3

    University of Hannover, Institute of Technical Chemistry, Department of Photocatalysis and Nanotechnology, Callinstr. 3-3A, D-30167, Hannover, Germany

Publication History

  1. Published Online: 13 SEP 2013
  2. Published Print: 23 OCT 2013

ISBN Information

Print ISBN: 9783527332137

Online ISBN: 9783527658985

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Keywords:

  • In situ photocatalytic studies;
  • intermediates;
  • radical formation and surface species;
  • partial oxidation and degradation of organics;
  • reaction mechanism and pathways;
  • reactive oxygen species;
  • local structure of transition metal sites;
  • charge separation and electron-hole formation and transfer

Summary

The state of the art of the application of physicochemical methods such as FTIR, EPR, UV–vis, XPS, NMR, XAFS, and fluorescence and chemiluminescence spectroscopies for oxidative in situ photocatalytic investigations is compiled. In situ FTIR studies yield valuable information about surface species, reaction intermediates, mechanisms, and pathways, as exemplified with partial oxidation or oxidative photocatalytic degradation with NOx, and organics such as alkenes, alkanes, alcohols, aldehydes, and carboxylic acids and chlorine- or fluorine-substituted compounds. Whereas EPR investigations provide information about fundamental photocatalytic properties of the catalysts such as charge separation and charge transfer, the formation of reactive oxygen species as well as local structure and oxidation state of EPR active transition metal sites, such as Cr, and other supported transition metal single sites such as Mo, V, Fe, Cu, Ti, and Ce in combination with UV–vis and XAFS measurements. The chemical composition and phase changes of the catalyst surface and the formation of carbonaceous species are studied by XPS. Some cases report the application of CW-CRDS (continuous-wave cavity ring down spectroscopy) in the NIR range for the determination of gas phase hydroxyl radicals over the catalysts, NMR for determination of partial oxidation products, or fluorescence and chemiluminescence techniques as analytical tool for in situ monitoring of the course of the photocatalytic reaction. Many studies use available in situ FTIR and complementary in situ EPR, the combination of which provides the most powerful and comprehensive tool for studying photocatalysis. Therefore, most in situ photocatalytic investigations make use of FTIR and EPR spectroscopies. Other methods are comparatively rarely used, obviously because of lower availability and experimental challenges. Despite the obvious progress achieved with in situ techniques, the number of studies is still limited. Furthermore, results are difficult to compare because of the numerous number of different experimental conditions applied such as different light sources, concentrations, and used facilities.