The modest liquid-phase solubility of CO2 in most solvents at ambient conditions presents a challenge to the development of electrocatalytic schemes for CO2 reduction. CO2-eXpanded Electrolytes (CXEs) are electrolyte solutions that enable access to multimolar concentrations of CO2 in the liquid phase, offering the opportunity to access improved CO2 conversion behavior under moderate CO2 gas pressures. Here, we will describe a study of CXE media and a pair of molecular electrocatalysts for CO2 reduction with the goal of understanding how the molecular structure of the catalysts affects their electrocatalytic performance in CXEs. Through cyclic voltammetric studies paired with foot-of-the-wave analysis (FOWA), we have mapped the pressure dependence of the catalyst kinetics, revealing that the catalysts operate at higher rates in our CXE media than those accessible at ambient conditions. In line with the behavior of the selected catalysts under ambient conditions, however, the catalyst that operates with the higher overpotential has been found to display faster kinetics. We have also found that both of the catalysts access their intrinsic, maximal rates of CO2 conversion in CXEs, a finding that underscores the importance of tuning substrate concentration to enable effective catalysis. Our latest results will be discussed, including quantification of the products of catalysis and the lifetimes of the molecular catalysts.

Tuning electrocatalytic CO2 reduction in CO2-expanded electrolytes

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