Graphite Oxide with Different Oxygenated Levels for Hydrogen and Oxygen Production from Water under Illumination: The Band Positions of Graphite Oxide
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- 作者：Te-Fu Yeh ; Fei-Fan Chan ; Chien-Te Hsieh ; Hsisheng Teng
- 刊名：Journal of Physical Chemistry C
- 出版年：2011
- 出版时间：November 17, 2011
- 年：2011
- 卷：115
- 期：45
- 页码：22587-22597
- 全文大小：1147K
- 年卷期：v.115,no.45(November 17, 2011)
- ISSN：1932-7455
文摘
Graphite oxide (GO) photocatalysts derived from graphite oxidation can have varied electronic properties by varying the oxidation level. Absorption spectroscopy shows the increasing band gap of GO with the oxygen content. Electrochemical analysis along with the Mott鈥揝chottky equation show that the conduction and valence band edge levels of GO from appropriate oxidation are suitable for both the reduction and the oxidation of water. The conduction band edge shows little variation with the oxidation level, and the valence band edge governs the bandgap width of GO. The photocatalytic activity of GO specimens with various oxygenated levels was measured in methanol and AgNO3 solutions for evolution of H2 and O2, respectively. The H2 evolution was strong and stable over time, whereas the O2 evolution was negligibly small due to mutual photocatalytic reduction of the GO with upward shift of the valence band edge under illumination. The conduction band edge of GO showed a negligible change with the illumination. When NaIO3 was used as a sacrificial reagent to suppress the mutual reduction mechanism under illumination, strong O2 evolution was observed over the GO specimens. The present study demonstrates that chemical modification can easily modify the electronic properties of GO for specific photosynthetic applications.