Tracking Co(I) Intermediate in Operando in Photocatalytic Hydrogen Evolution by X-ray Transient Absorption Spectroscopy and DFT Calculation
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- 作者：Zhi-Jun Li ; Fei Zhan ; Hongyan Xiao ; Xiaoyi Zhang ; Qing-Yu Kong ; Xiang-Bing Fan ; Wen-Qiang Liu ; Mao-Yong Huang ; Cheng Huang ; Yu-Ji Gao ; Xu-Bing Li ; Qing-Yuan Meng ; Ke Feng ; Bin Chen ; Chen-Ho Tung ; Hai-Feng Zhao ; Ye Tao ; Li-Zhu Wu
- 刊名：The Journal of Physical Chemistry Letters
- 出版年：2016
- 出版时间：December 15, 2016
- 年：2016
- 卷：7
- 期：24
- 页码：5253-5258
- 全文大小：477K
- ISSN：1948-7185
文摘
X-ray transient absorption spectroscopy (XTA) and optical transient spectroscopy (OTA) were used to probe the Co(I) intermediate generated in situ from an aqueous photocatalytic hydrogen evolution system, with [RuII(bpy)3]Cl2·6H2O as the photosensitizer, ascorbic acid/ascorbate as the electron donor, and the Co-polypyridyl complex ([CoII(DPA-Bpy)Cl]Cl) as the precatalyst. Upon exposure to light, the XTA measured at Co K-edge visualizes the grow and decay of the Co(I) intermediate, and reveals its Co–N bond contraction of 0.09 ± 0.03 Å. Density functional theory (DFT) calculations support the bond contraction and illustrate that the metal-to-ligand π back-bonding greatly stabilizes the penta-coordinated Co(I) intermediate, which provides easy photon access. To the best of our knowledge, this is the first example of capturing the penta-coordinated Co(I) intermediate in operando with bond contraction by XTA, thereby providing new insights for fundamental understanding of structure–function relationship of cobalt-based molecular catalysts.