Spectroscopic Characterisation of a Bio-Inspired Ni-Based Proton Reduction Catalyst Bearing a Pentadentate N2S3 Ligand with Improved Photocatalytic Activity |
| |
Authors: | Dr Philipp Gotico Dr Dooshaye Moonshiram Dr Cunming Liu Dr Xiaoyi Zhang Dr Régis Guillot Dr Annamaria Quaranta Dr Zakaria Halime Dr Winfried Leibl Prof Ally Aukauloo |
| |
Institution: | 1. Institut de Biologie Integrative de la Cellule (I2BC), Institut des Sciences du Vivant Frédéric-Joliot, CEA Saclay, 91191 Gif-sur-Yvette, France;2. Instituto Madrileño de Estudios Avanzados en Nanociencia, (IMDEA Nanocienca), Calle Faraday 9, Madrid, 28049 Spain;3. X-ray Science Division, Argonne National Laboratory, 9700 S. Cass Avenue, Lemont, IL, 60439 USA;4. Institut de Chimie Moléculaire et des Matériaux d'Orsay (ICMMO), UMR 8182 CNRS, Université Paris Sud, 91405 Orsay, France |
| |
Abstract: | Inspired by the sulfur-rich environment found in active hydrogenase enzymes, a Ni-based proton reduction catalyst with pentadentate N2S3 ligand was synthesised. When coupled with Ru(bpy)3]2+ (bpy=2,2′-bipyridine) as photosensitiser and ascorbate as electron donor in a 1:1 mixture of dimethylacetamide and aqueous ascorbic acid/ascorbate buffer, the catalyst showed improved photocatalytic activity compared with a homologous counterpart bearing a tetradentate N2S2 ligand. The mechanistic pathway of photoinduced hydrogen evolution was comprehensively analysed through optical transient absorption and time-resolved X-ray absorption spectroscopy, which revealed important electronic and structural changes in the catalytic system during photoirradiation. The NiII catalyst undergoes a photoinduced metal-centred reduction to form a NiI intermediate with distorted square-bipyramidal geometry. Further kinetic analyses revealed differences in charge-separation dynamics between the pentadentate and tetradentate forms. |
| |
Keywords: | nickel photochemistry reaction mechanisms time-resolved spectroscopy X-ray absorption spectroscopy |
|
|