Effect of the Hydrogen Bond in Photoinduced Water Dissociation: A Double-Edged Sword

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• 作者：Wenshao Yang ; Dong Wei ; Xianchi Jin ; Chenbiao Xu ; Zhenhua Geng ; Qing Guo ; Zhibo Ma ; Dongxu Dai ; Hongjun Fan ; Xueming Yang
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2016
• 出版时间：February 18, 2016
• 年：2016
• 卷：7
• 期：4
• 页码：603-608
• 全文大小：392K
• ISSN：1948-7185

文摘

Photoinduced water dissociation on rutile-TiO₂ was investigated using various methods. Experimental results reveal that the water dissociation occurs via transferring an H atom to a bridge bonded oxygen site and ejecting an OH radical to the gas phase during irradiation. The reaction is strongly suppressed as the water coverage increases. Further scanning tunneling microscopy study demonstrates that hydrogen bonds between water molecules have a dramatic effect on the reaction. Interestingly, a single hydrogen bond in water dimer enhances the water dissociation reaction, while one-dimensional hydrogen bonds in water chains inhibit the reaction. Density functional theory calculations indicate that the effect of hydrogen bonds on the OH dissociation energy is likely the origin of this remarkable behavior. The results suggest that avoiding a strong hydrogen bond network between water molecules is crucial for water splitting.