(17c) Mechanisms of Carbon-Carbon Coupling in CO2 Electroreduction On Cu(211)

Copper uniquely catalyzes artificial photosynthesis via electroreduction of CO2. With sustainable sources of electricity, electrocatalytic CO2 reduction offers a carbon-neutral method of fuel production. Methane formation energetics on copper have been previously determined by Peterson et al. However, C2H4 and other C-C coupled species produced in CO2 electroreduction have high utility and value as potential liquid fuel and fine chemical feedstocks. Using density functional theory, we present energetics of possible intermediary processes to C2H4 formation on Cu in order to build a framework of relevant thermodynamic and kinetic trends for design strategies to improve selectivity and activity in CO2 electroreduction catalysis. in particular, we use the nudged elastic band (NEB) method to identify transition states for reactions between CO-derived adsorbates.  We identify a trend of decreasing barriers as CO-derived intermediates become more hydrogenated, suggesting that kinetics of C-C bond formation improve with increasing potential.  In addition, we compare our results to experimental trends in order to fit this paradigm of C-C coupling into the overall trends in selectivity for CO2 electrocatalysis.  Ultimately, these results provide a basis for the design of new catalysts for selective CO2 electroreduction.