Hydrogenation and hydrogen diffusion at the anatase TiO2(101) surface
Naoki Nagatsuka1, Markus Wilde1, Katsuyuki Fukutani1
1Institute of Industrial Science, The University of Tokyo, Komaba Meguro-ku, Tokyo 153-8505, Japan.
The Journal of Chemical Physics
|February 24, 2020
Summary
Hydrogenation of titanium dioxide (TiO2) creates in-gap states and band bending, enhancing photocatalysis. Hydrogen diffusion in anatase TiO2 is significantly faster than in rutile TiO2, with a determined diffusion coefficient at 200 K.
Area of Science:
- Materials Science
- Surface Science
- Photocatalysis
Background:
- Hydrogenation of titanium dioxide (TiO2) improves visible light absorption and photocatalytic efficiency.
- The precise role of hydrogen in TiO2 hydrogenation remains incompletely understood.
Purpose of the Study:
- To investigate the effects of hydrogen ion irradiation on the anatase TiO2(101) surface.
- To elucidate the electronic structure modifications and hydrogen behavior within TiO2.
Main Methods:
- Photoemission spectroscopy was employed to analyze electronic structure changes.
- Nuclear reaction analysis was used to determine hydrogen depth profiles.
- Hydrogen ion irradiation at 500 eV was performed on anatase TiO2.
Main Results:
- Hydrogen irradiation induced in-gap states 1-1.6 eV below the Fermi level and downward band bending of 0.27 eV.
- Hydrogen diffusion in anatase TiO2 was found to be significantly faster than in rutile TiO2.
- The hydrogen diffusion coefficient in anatase TiO2 at 200 K was determined to be 2.7 ± 0.1 × 10⁻¹³ m²/s.
Conclusions:
- Hydrogen incorporation in TiO2 leads to significant electronic structure modifications.
- The study provides quantitative data on hydrogen diffusion in anatase TiO2, crucial for optimizing photocatalytic applications.
- Understanding hydrogen behavior is key to harnessing TiO2's enhanced photocatalytic potential.
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