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Bio-inspired [NiFe] Hydrogenase Catalysts for H2 production

Subject Area Inorganic Molecular Chemistry - Synthesis and Characterisation
Biological and Biomimetic Chemistry
Term from 2016 to 2022
Project identifier Deutsche Forschungsgemeinschaft (DFG) - Project number 316698085
 
Final Report Year 2024

Final Report Abstract

Dihydrogen (H2) production through catalytic water splitting is a key reaction of future sustainable energy scenarios. Nature offers very efficient H2 evolution catalysts in the form of hydrogenases, which are organometallic enzymes containing nickel and/or iron active sites and whose catalytic performances rival commonly used platinum catalysts for H2 generation. Hydrogenases thus represent blueprints for the design of innovative molecular catalysts based on earth-abundant metals. Starting from a high fidelity structural and functional model complex for the heterodinuclear [NiFe]-hydrogenase active site, published by the consortium at the outset of this collaborative project, joint work by the French/German team has now derived structure/activity correlations that have led to better understanding of the reactivity of the bimetallic core and that have paved the way towards improved bioinspired catalysts. Specifically, detailed insights have been obtained by mechanistic investigations, and variations of peripheral ligands of the [NiFe]-hydrogenase mimic as well as comparing NiFewith corresponding FeFe-systems have defined key structural and electronic factors for optimal reactivity. During the course of these studies an unusual iron(III)-thiolate/iron(II)-disulfide (inter)conversion has been discovered and a dinuclear iron-thiol/thiolato complex was found to serve as an efficient catalyst for the oxygen reduction reaction (ORR) with tuneable selectivity for water or hydrogen peroxide. Thorough mechanistic analysis provided valuable information about the dioxygen activation trajectories and the prevention of S-centered reactivity in thiolato-ligated non-heme iron sites. As a side branch of this project, the development of robust nickel(II)-based metalloligands led to a new strategy for enhancing single molecule magnet (SMM) properties of 3d metal complexes with hard O-donors. The entire project benefitted greatly from the complementary expertise of the French and German partner laboratories and the excellent collaborative spirit.

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