Photoexcited Surface Frustrated Lewis Pairs for Heterogeneous Photocatalytic CO2 Reduction

详细信息    查看全文

• 作者：Kulbir Kaur Ghuman ; Laura B. Hoch ; Paul Szymanski ; Joel Y. Y. Loh ; Nazir P. Kherani ; Mostafa A. El-Sayed ; Geoffrey A. Ozin ; Chandra Veer Singh
• 刊名：Journal of the American Chemical Society
• 出版年：2016
• 出版时间：February 3, 2016
• 年：2016
• 卷：138
• 期：4
• 页码：1206-1214
• 全文大小：490K
• ISSN：1520-5126

文摘

In this study we investigated, theoretically and experimentally, the unique photoactive behavior of pristine and defected indium oxide surfaces providing fundamental insights into their excited state properties as well as an explanation for the experimentally observed enhanced activity of defected indium oxide surfaces for the gas-phase reverse water gas shift reaction, COb>2b> + Hb>2b> + hν→ CO + Hb>2b>O in the light compared to the dark. To this end, a detailed excited-state study of pristine and defected forms of indium oxide (Inb>2b>Ob>3b>, Inb>2b>Ob>3–xb>, Inb>2b>Ob>3b>(OH)b>yb> and Inb>2b>Ob>3–xb>(OH)b>yb>) surfaces was performed using time dependent density functional theory (TDDFT) calculations, the results of which were supported experimentally by transient absorption spectroscopy and photoconductivity measurements. It was found that the surface frustrated Lewis pairs (FLPs) created by a Lewis acidic coordinately unsaturated surface indium site proximal to an oxygen vacancy and a Lewis basic surface hydroxide site in Inb>2b>Ob>3–xb>(OH)b>yb> become more acidic and basic and hence more active in the ES compared to the GS. This provides a theoretical mechanism responsible for the enhanced activity and reduced activation energy of the photochemical reverse water gas shift reaction observed experimentally for Inb>2b>Ob>3–xb>(OH)b>yb> compared to the thermochemical reaction. This fundamental insight into the role of photoexcited surface FLPs for catalytic COb>2b> reduction could lead to improved photocatalysts for solar fuel production.