Energetically Efficient (De-)Hydrogenations

Environmental consequences of increased levels of CO₂ in the atmosphere make the development of renewable fuel technologies imperative. Electrochemical reduction of CO₂ to more active molecules is one approach to produce an alternative fuel and reduce CO₂ release into the atmosphere. There is a growing body of literature implicating aromatic N-heterocycles as co-catalysts for CO₂ reduction under certain experimental conditions. Our aim is to better understand these reaction mechanisms to help guide the design of improved catalysts.

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Our working hypothesis for these reactions is that certain experimental conditions can allow these molecules to act as multi-proton and electron shuttles to CO₂. The reaction conditions that would facilitate these reactions can be identified by calculating Pourbaix diagrams for the catalysts in question that denote the pH and electrode potential where different catalyst states have equivalent chemical potentials. This in turn shows the experimentally relevant conditions where energetically efficient and reversible proton and electron shuttling would be thermodynamically possible. Within this framework we can predict new catalysts that should be more effective for energetically efficient (de-)hydrogenations.

The Pourbaix diagram investigations carried out by our group consider the thermodynamic feasibility of energetically efficient reactions, but they do not address the kinetic feasibility of these reactions. To reliably model reaction kinetics, we are testing different computational approaches to study the role of explicit interactions with solvents and co-solutes with sufficiently high levels of quantum chemistry theory (see theory development projects).