Chapter 2. Modeling and Simulation of Photocatalytic Reactions at TiO2 Surfaces

  1. Lionel Vayssieres
  1. Hideyuki Kamisaka and
  2. Koichi Yamashita

Published Online: 2 MAR 2010

DOI: 10.1002/9780470823996.ch2

On Solar Hydrogen & Nanotechnology

On Solar Hydrogen & Nanotechnology

How to Cite

Kamisaka, H. and Yamashita, K. (2010) Modeling and Simulation of Photocatalytic Reactions at TiO2 Surfaces, in On Solar Hydrogen & Nanotechnology (ed L. Vayssieres), John Wiley & Sons, Ltd, Chichester, UK. doi: 10.1002/9780470823996.ch2

Editor Information

  1. National Institute for Materials Science, Japan

Author Information

  1. Department of Chemical System Engineering, School of Engineering, The University of Tokyo, Tokyo 113-8656, Japan

Publication History

  1. Published Online: 2 MAR 2010
  2. Published Print: 4 JAN 2010

ISBN Information

Print ISBN: 9780470823972

Online ISBN: 9780470823996

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Keywords:

  • Keyword for “Modeling and Simulation of Photocatalytic Reactions”;
  • Hideyuki Kamisaka and Koichi Yamashita;
  • TiO2;
  • Photocatalysis;
  • Solar cell;
  • First-principle method;
  • Chemical bond;
  • Chemical reaction;
  • Density functional thoery;
  • DFT;
  • Doping;
  • C-doped TiO2;
  • Visible light activity;
  • TNO;
  • Nb-doped TiO2;
  • Transparent conductive oxide;
  • TCO;
  • Oxygen vacancy;
  • Reactive intermediate;
  • Photo induced hydrophilicity;
  • surface stress;
  • TiO2;
  • Surface hydroxyl group;
  • Adsorbed water;
  • Dye-sensitized solar cell;
  • DSSC;
  • Quantum dot;
  • QD;
  • PbSe;
  • Multi exciton generation;
  • MEG;
  • Decoherence;
  • Local excited states;
  • Nonadiabatic process;
  • Open system;
  • Semi-infinite;
  • Embedding;
  • QM/MM;
  • Molecular Mechanics;
  • DFT functional;
  • ab initio MD

Summary

This chapter explains why the surface chemistry of TiO2 is important. Several phenomena, such as photocatalysis, photo-induced hydrophillic conversion, and the fabrication of solar cell, are introduced. The limitation of the current knowledge about the phenomena is pointed out. The necessity and strength of the first-principle method is emphasized in terms of the description of chemical reaction process.

The optical and electronical properties of TiO2 bulk can be significantly changed by doping impurities. At the beginning of this chapter, recent trends in the doping of TiO2 are briefly reviewed. Then our recent theoretical calculations about carbon doped TiO2 (C-doped TiO2) and niobium doped TiO2 (Nb-doped TiO2) is reviewed. The former is intended to improve the photocatalytic reaction activity of TiO2 under visible light. The latter, known as TNO, is expected to be an alternative transparent conductive oxide (TCO).

Several chemical active intermediate species are speculated to be the key of the photocatalytic reactivity of TiO2 surfaces. However, the identification of the actual active species had been controversy. A brief historical review is given, and proceeding theoretical works are introduced related to this subject. Especially, our recent study on the adsorbed water and hydroxyl groups, and its effect on surface stress are focused. These structures are expected to be the key factor for the clarification of photo-induced hydrophilicity.

The TiO2 surface consist a solar cell device when some kind of dye molecules is adsorbed. Proceeding theoretical researches on DSSC with conventional organic sensitizers are reviewed. In addition to that, novel type of DSSC using quantum dots as sensitizer is under development recently. The performance of DSSC is expected to be significantly improved in the latter, utilizing a phenomenon known as multiple exciton generation. Recent theoretical analyses of the MEG process are reviewed.

The limitation of the present theoretical framework is pointed out, and the future direction is discussed. Especially, the absence of the proper description of the electronically excited states and its associated nonadiabatic transitions are emphasized. Their fundamental difficulty and its potential remedies are introduced. Along with these serious theoretical concerns, several combined approaches such as semiempirical method and methodologies based on molecular mechanics are reviewed.