The solar-to-fuel approach is one of the main ways to achieve solar energy conversion. Among solar fuels, molecular hydrogen stands out, since it can be utilized pollution-free. The electrons needed to sustainable reduce protons to molecular hydrogen can be provided by natural and artificial photosensitizers. The use of natural Photosystems takes advantage of nature’s optimized light-harvesting and electron-transfer capabilities, while artificial photosensitizers provide a large variety of chromophores. Incorporation of abiotic hydrogen catalysts in protein surrounding has the potential to create the proper microenvironment for efficient catalysis under aqueous conditions and thus eliminate the use of organic solvents. Furthermore, the protein environment can stabilize them and thus overcome one of their weaknesses – low stability. To achieve sustainable hydrogen generation, the catalysts should not be rare and expensive, but use earth abundant elements like first row transition metals. Cobaloxime and other mononuclear cobalt complexes are among the best molecular transition metal systems for the reduction of protons to molecular hydrogen. Knowledge of the electronic properties is important for an in-depth understanding of the catalytic properties of the complexes. These properties depend not only on the chemical structure of the complexes but also on the local surrounding and on the direct ligands to the central metal ion. Multi-frequency Electron Paramagnetic Resonance (EPR) spectroscopy at X-band (9 GHz), Q-band (34 GHz), and D-band (130 GHz) has been used to investigate these cobalt complexes, allowing us to determine the electronic g-tensors and hyperfine interaction with various magnetic nuclei like 59Co, 14N, and 31P. The experimental results are supplemented with DFT calculations. The knowledge gained by these model studies is used to characterize the binding of the hydrogen catalysts to proteins as well as mechanism of hydrogen generation in these protein-catalyst system.

Light-driven molecular hydrogen generation with cobalt-based catalysts studied by multifrequency EPR and DFT

Fall 2022 abstracts, posters, and presentations will launch in mid-September.

ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.