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Investigation of the ultrafast dynamics occurring during unsensitized photocatalytic H2 evolution by an [FeFe]-hydrogenase subsite analogue
- Publication Year :
- 2014
-
Abstract
- Biomimetic compounds based upon the active subsite of the [FeFe]-hydrogenase enzyme system have been the focus of much attention as catalysts for hydrogen production: a clean energy vector. Until recently, use of hydrogenase subsite systems for light-driven hydrogen production has typically required the involvement of a photosensitizer, but the molecule [(μ-pdt)(μ-H)Fe2(CO)4(dppv)]+, (1; dppv = cis-1,2-C2H2(PPh2)2; pdt = 1,3-propanedithiolate) has been reported to catalyze the evolution of hydrogen gas under sensitizer-free conditions. Establishing the molecular mechanism that leads to photohydrogen production by 1 is thus an important step that may enable further development of this family of molecules as solar fuel platforms. Here, we report ultrafast UVpump–IRprobe spectroscopy of 1 at three different excitation wavelengths and in a range of solvents, including under the conditions required for H2 production. Combining spectroscopic measurements of the photochemistry and vibrational relaxation dynamics of 1 with ground-state density functional theory (DFT) calculations shows that, irrespective of experimental conditions, near-instantaneous carbonyl ligand loss is the main photochemical channel. No evidence for a long-lived excited electronic state was found. These results provide the first time-resolved data for the photochemistry of 1 and offer an alternative interpretation of the underlying mechanism of light-driven hydrogen generation.
Details
- Language :
- English
- ISSN :
- 02767333
- Database :
- OpenAIRE
- Accession number :
- edsair.doi.dedup.....7b21437b25fe2ed366fb47e1eec84dea