Simulations of electrochemical processes with application to CO2 reduction and hydrogen evolution reaction
- Hannes Jónsson (University of Iceland)
- Monday 30 March 2020
- Hotel NH Noordwijk Conference Centre Leeuwenhorst
Faculty of Physical Sciences, Univ. of Iceland
Computer simulations of electrochemical processes are challenging because of the need to represent the effect of the electrolyte on the catalytic processes. Advanced simulation methods are needed to evaluate the effect applied voltage on the activation energy and the rate of the various elementary steps. A methodology for such simulations will be presented and application to electrochemical CO2 reduction to formate, alcohols and hydrocarbons will be presented.
The mechanism for the formation of the various products is established, the rate evaluated and comparison made with experimental measurements. The rate of the main side reaction, the hydrogen evolution reaction, is also estimated. The calculations are based on a detailed atomistic model of the electrical double layer (metal slab and water layer) and density functional theory calculations to evaluate not only the free energy of intermediates as a function of applied voltage but also the activation energy for each elementary step, both Heyrovsky and Tafel reactions . Comparison is also made with calculations using an implicit solvation model  as well as explicit aqueous electrolyte using a QM/MM approach . A range of close packed metal surfaces are compared, including Cu, Ag, Au, Ni, Fe, Rh, Ir and Pt. The results are in remarkably good agreement with the reported experimental measurements. A two parameter descriptor is established that can help identify improved catalysts for CO2 electrochemical reduction.
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