Control of Photoactivity over Polycrystalline Anatase TiO2 Thin Films via Surface Potential

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• 作者：S. W. Daniel Ong ; Jianyi Lin ; Edmund G. Seebauer
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：December 3, 2015
• 年：2015
• 卷：119
• 期：48
• 页码：27060-27071
• 全文大小：663K
• ISSN：1932-7455

文摘

The utility of thin-film TiO₂ for photocatalysis would be greatly improved if the spatial variation of the electronic band edges near the surface could be engineered a priori to control the current of photogenerated minority carriers. The present work demonstrates such a concept. In particular, remote oxygen plasma treatment of polycrystalline anatase TiO₂ with specified majority carrier concentration is employed in the test case of methylene blue photodegradation. The photoreaction rate varies by up to 35% in concert with a 0.4 eV change in built-in surface potential measured by photoelectron spectroscopy. The correlation between these changes agrees quantitatively with a photodiode鈥損hotocurrent model. The plasma treatment affects concentration of charged native defects within the first few atomic layers of the surface, most likely by lowering the concentration of oxygen vacancies within surface crystallites. In tandem, the position in the deep bulk is controlled via engineering the defect concentration at grain boundaries, thus illustrating the coordinated use of multiple defect engineering practices in polycrystalline material to accomplish quantitative manipulation of band bending and corresponding photocurrent.