Axis I : Bioinspired multielectronic catalysis
Multielectron/multiproton transfer reactions are at the core of important biological and chemical processes, such as small molecule activation and energy conversion. Optimization of these kinetically constrained reactions is a critical challenge for energy-related applications. Nature widely utilizes first-row transition metals in enzymes to catalyze these processes under ambient conditions and we develop a bioinspired approach to design bioinspired catalytic platforms for H2 evolution, CO2 valorization and N2 fixation.
We further exploit all these catalysts through integration in carbon nanotube-based electrodes (Axis II) or assembly with various light-harvesting units to form artificial photosynthetic systems (Axis III).
In particular, hydrogen production and uptake are two reactions efficiently catalyzed by enzymatic sites such as the dinuclear NiFe and FeFe clusters in hydrogenases and during the last decade, intensive research efforts have been devoted in our team to the development of biomimetic and bioinspired H2-evolving catalysts based on Ni, Fe and Co centres.
The design of biomimetic catalysts for H2 evolution has been the core expertise of the SolHyCat team since 2002. Since 2006, our group has reported novel catalysts reproducing key structural, spectroscopic and reactivity features of the active site of [NiFe] hydrogenases.
We also investigate cobalt complexes as H2 evolution catalysts. This includes our earlier work on cobaloximes and cobalt diimine-dioxime complexes as well as our current development of novel catalytic platforms such as the [Co(bapbpy]2+ complexes. For all these molecular catalysts, we apply state-of-the art analysis of the electrocatalytic response to determine the catalytic mechanism, identify the role of redox-active moieties and proton relays (oxime bridge, pendant amine groups…) and benchmark their catalytic activity with other molecular catalysts for the literature.
CO2 valorization and N2 fixation
The active sites of CODH and formate-dehydrogenase contain basic sites in the vicinity of the metal sites where CO2 is activated. We apply bio-inspiration concepts to design novel molecular catalytic platforms for CO2 conversion. In that prospect, cobalt complexes such as [CpCoP2N2)] (figure) again prove quite promising.
A natural evolution of our research interests to even more challenging multielectron/multiproton transfer reactions led us to question the fundamental basis of nitrogen reduction to ammonia by diazotrophic organisms. To this purpose, we are actively developing versatile multivalent ligands platforms able to stabilize discrete metal sulfide clusters reminiscent of the natural poly(hetero)metallic sulfides co-factors that are supporting nitrogen reduction in nitrogenases. A systematic investigation of the reactivity of our synthetic constructs towards various substrates of this enzyme will help us deciphering the critical parameters governing the activity of this fascinating class of biomolecules