Insights into the Role of Surface Distortion in Promoting the Separation and Transfer of Photogenerated Carriers in Anatase TiO2

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• 作者：Xiangchao Ma ; Ying Dai ; Meng Guo ; Baibiao Huang
• 刊名：Journal of Physical Chemistry C
• 出版年：2013
• 出版时间：November 21, 2013
• 年：2013
• 卷：117
• 期：46
• 页码：24496-24502
• 全文大小：493K
• 年卷期：v.117,no.46(November 21, 2013)
• ISSN：1932-7455

文摘

The general low quantum efficiency of semiconductor-based photocatalysts significantly limits their large-scale application. Here, we reveal the potential role that surface distortion can play in enhancing the photocatalytic quantum efficiency as well as the underlying mechanism by using TiO₂ as a model photocatalyst. Specifically, proper surface distortion in a {101} surface can significantly promote the participation of electrons in photocatalytic reactions and further facilitate the transfer of photogenerated electrons in the bulk region to this surface. Moreover, surface distortion also prevents the photogenerated holes from transferring to the surface layer, thus separating the photogenerated holes from electrons and reducing the high recombination rate of carriers, which is believed to result in the generally low photocatalytic activities of the {101} surface. For the {001} surface, the distorted surface greatly promotes the transfer of electrons from the subsurface atomic layer (the initial electron trapping sites) to the outermost atomic layer (where photocatalytic reactions generally occur) by eliminating the original energy barrier, and the trapping of electrons on surface Ti_5c d_z² orbital cannot only facilitate their participation in the photocatalytic reactions but also significantly reduce the carrier recombination rate in the surface region. The results presented here can be used to account for the experimental results that surface distortion in TiO₂ can substantially improve the quantum efficiency of its intrinsic absorption.