Synthesis of optimised hydrogen production catalysts
In first instance, two existing proton reduction catalysts, based on Ni or Co are attached to an Si nanowire electrode surface, either via covalent “plug-and-play” anchoring strategies using phosphate (PO3H2), silanol (Si(OR)3) or carboxylate (COOH) functionalities or via supramolecular bonding motives using hydrogen bonding or concepts, allowing for simple assembly of active, well defined catalytic systems.
After this benchmarking stage, we aim for significant improvements of these systems - as well as dinuclear analogues thereof – by ligand sphere alterations, optimization of linkage methodologies, the incorporation of functional groups to allow lower over-voltages (i.e. cooperative and bifunctional mechanisms for H2 formation) and the use of porous supramolecular aggregates. We will also develop Fe-based systems for anchoring to the Si-nanowire system.
Critical factors are catalyst activation for PCET, redox leveling and thermodynamic stabilization of intermediates in the 2-electron process, variation of the bite angle for release of hydrogen to avoid that structural rearrangements become rate-limiting instead of the PCET steps. The optimization will be evidence-based, and will be performed in close collaboration with the time resolved laser and freeze hyperquenching NMR analysis projects that feed into the constrained molecular modeling of catalysis mechanisms. The supramolecular catalyst are then incorporated into thesemiconductor heterojunction tandem device that is the focus of artifical leaves.
The work in this project is primarily done at the Supramolecular & Homogeneous Catalysis department of the van ‘t Hoff Institute for Molecular Sciences, Science Park Amsterdam, Amsterdam University.