Results of theoretical calculations of electrochemical CO2 reduction where the mechanism of the reaction is established and the rate of this reaction as well as the main side reaction, hydrogen formation, is estimated quantitatively. We use a detailed atomistic model of the electric double layer (metal slab and water layer, see figure) and DFT 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. We compare a range of close packed metal surfaces (including Cu, Ag, Au, Ni, Fe, Rh, Ir and Pt) and evaluate the current density for both CO2 reduction and hydrogen formation. The resuls are in remarkably good agreement with measurements [1,2,3,4]. A two parameter descriptor is established that can help identify improved catalysts for this important reaction. The elucidation of the reaction mechanism of CO2 electroreduction to methane as well as the competing hydrogen evolution reaction is an important step towards the design of a selective and energy efficient catalyst for small scale, decentralized fuel production using renewable energy sources and CO2 as reactant.<br/><br/>[1] Y. Hori, Modern Aspects of Electrochemistry; Vayenas, White, Gamboa-Aldeco, Eds. (Springer, New York, 2008) 42, p. 89; K.J.P. Schouten et al., Chem. Sci. 2, 1902 (2011); K.P. Kuhl et al., Energy Environ. Sci. 5, 7050 (2012); K.P. Kuhl et al., J. Am. Chem. Soc. 136, 14107 (2014).

Calculations of electrochemical reduction of CO2 to methane and the competing H2 formation

251st National Meeting (2016)

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