Activation of base metals for electrocatalytic water oxidation
Title: Activation of base metals for electrocatalytic water oxidation
SNIC Project: SNIC 2021/5-474
Project Type: SNIC Medium Compute
Principal Investigator: Johannes Messinger <johannes.messinger@kemi.uu.se>
Affiliation: Uppsala universitet
Duration: 2021-11-01 – 2022-11-01
Classification: 10402 10407 10404
Homepage: https://katalog.uu.se/profile/?id=N16-1398
Keywords:

Abstract

Even in the well-electrified Sweden, 70% of the energy is consumed as fuel, and most liquid fossil fuels are used in the transport sector. Due to the low solar-to-biomass energy storage efficiency of plants (< 0.5%), local biomass contributes only with less than 2.5% to the transportation fuels in Sweden. The expansion of the H2 refueling station network in Europe, and the release of H2 fuel cell vehicles to market, makes H2 an attractive alternative transportation fuel. Burning of H2 releases only water, and thus H2 is in principle a 'clean' fuel. Presently, the problem is that nearly all H2 is produced from fossil fuels since present electrolyzers are too expensive or unsuitable for intermittent operation. For bringing renewable energy driven electrolyzers to market, new cheap, efficient and stable catalysts are required. In this project, we focus on molecular catalysts for water oxidation made from base metals. The molecular approach has been very successful in converting the first molecular water-splitting catalyst, a Ru-dimer, from a poor catalyst to performing better than the natural system in photosynthesis. For meeting this challenge, we combine our local strong expertise in photosynthesis, coordination chemistry, electrochemistry, electron paramagnetic resonance (EPR) and X-ray spectroscopies, density-functional theory (DFT) and mechanistic studies to systematically study existing base metal water-splitting catalysts, and for designing catalysts with improved catalytic efficiency and stability. We have shown the effectiveness of the computational approach by previously analyzing in detail how the oxidation potential depends on the choice of base metal in the same ligand framework. We have also outlined a way to control electronic properties by introducing ligand modifications far away from the metal center, which mainly work through steric effects. This includes temperature-dependent spin-crossover behavior, magnetic anisotropy, oxidation potential as well as catalytic performance in water oxidation. In this project we will continue to how to achieve rational design of coordination complexes through control of metal-ligand interactions. One important development is the study of multi-nuclear metal catalysts using the same analysis framework that we have previously applied to mononuclear complexes. The close connection between experimental and theoretical results will enable us to rationalize the functional dependence of the predicted properties, which is important to understand the reliability of the theoretical results.