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Hydrogen production: Nickel centred proton reduction catalysis in a model of [NiFe] Hydrogenase

Currently, the production of hydrogen remains expensive because it requires noble metal catalysts such as platinum. In nature, hydrogenases present in microorganisms, use abundant and low cost metals to perform this operation under mild conditions. In a bio-inspired approach, researchers at the Chemistry and Biology of Metals Laboratory [collaboration] were able to synthesize a new catalyst reproducing this mechanism. These results are published in the journal Nature Chemistry.​

Published on 26 September 2016
In the race for clean energy, the development of processes to produce hydrogen via renewable resources such as water and solar energy is a highly attractive solution. Yet hydrogen production remains a costly process, due in particular to the use of platinum, a rare metal used as a catalyst in membrane electrolysis systems. Now, in a natural environment, for example in bacteria, certain enzymes act as a catalyst in the production of dihydrogen. These include hydrogenases [NiFe], which achieve high efficiency under mild conditions, and require metals as abundant as nickel or iron.

Reproducing the key elements of the active site of these enzymes within a synthetic molecule makes it possible to develop new types of catalysts without requiring noble metals. However, the nickel-iron biomimetic models described thus far do not reflect the nickel-ion-centered reactivity of the active site of these enzymes, as is the case in nature. This explains their limited performances. In this context, in collaboration with peers from Grenoble Alpes University and Aix-Marseille University, a research team from the Chemistry and Biology of Metals Laboratory has developed a model that relocates reactivity to the nickel center through the use of a bipyridine-dithiolate ligand. This new model is close to the activity of the enzyme as it involves two catalytic intermediates reproducing the structural and electronic characteristics of two states (Ni-L and Ni-R) of the enzymatic cycle. "The rate of hydrogen production catalyzed by this original compound clearly indicates the synergy between nickel and iron ions for hydrogen production," said Vincent Artero, researcher at the Chemistry and Biology of Metals Laboratory. A comparative evaluation of the performances of the new nickel-iron catalyst indicates that they significantly exceed the performances of other biomimetic models involving the coupling of two metals.

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