Tracking Co(I) Intermediate in operando in Photocatalytic Hydrogen Evolution by X-ray transient Absorption Spectroscopy and DFT Calculation
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(DPABpy) Cl]Cl) as the pre-catalyst. 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.
- Research Organization:
- Argonne National Laboratory (ANL)
- Sponsoring Organization:
- USDOE Office of Science - Office of Basic Energy Sciences - Scientific User Facilities Division
- DOE Contract Number:
- AC02-06CH11357
- OSTI ID:
- 1335169
- Journal Information:
- Journal of Physical Chemistry Letters, Journal Name: Journal of Physical Chemistry Letters Journal Issue: 7 Vol. 2016; ISSN 1948-7185
- Publisher:
- American Chemical Society
- Country of Publication:
- United States
- Language:
- English