Predictive energetic tuning of C-Nucleophiles for the electrochemical capture of carbon dioxide
Haley A. Petersen,
Abdulaziz W. Alherz,
Taylor A. Stinson,
Chloe G. Huntzinger,
Charles B. Musgrave,
Oana R. Luca
Affiliations
Haley A. Petersen
Department of Chemistry and Renewable and Sustainable Energy Institute, University of Colorado Boulder, Boulder, CO 80309, USA
Abdulaziz W. Alherz
Department of Chemical and Biological Engineering, University of Colorado, Boulder, CO 80309, United States
Taylor A. Stinson
Department of Chemistry and Renewable and Sustainable Energy Institute, University of Colorado Boulder, Boulder, CO 80309, USA
Chloe G. Huntzinger
Department of Chemistry and Renewable and Sustainable Energy Institute, University of Colorado Boulder, Boulder, CO 80309, USA
Charles B. Musgrave
Department of Chemistry and Renewable and Sustainable Energy Institute, University of Colorado Boulder, Boulder, CO 80309, USA; Department of Chemical and Biological Engineering, University of Colorado, Boulder, CO 80309, United States; Materials Science and Engineering Program, University of Colorado, Boulder, CO 80309, United States; Corresponding author
Oana R. Luca
Department of Chemistry and Renewable and Sustainable Energy Institute, University of Colorado Boulder, Boulder, CO 80309, USA; Corresponding author
Summary: This work maps the thermodynamics of electrochemically generated C-nucleophiles for reactive capture of CO2. We identify a linear relationship between the pKa, the reduction potential of a protonated nucleophile (Ered), and the nucleophile’s free energy of CO2 binding (ΔGbind). Through synergistic experiments and computations, this study establishes a three-parameter correlation described by the equation ΔGbind=−0.78pKa+4.28Ered+20.95 for a series of twelve imidazol(in)ium/N-heterocyclic carbene pairs with an R2 of 0.92. The correlation allows us to predict the ΔGbind of C-nucleophiles to CO2 using reduction potentials or pKas of imidazol(in)ium cations. The carbenes in this study were found to exhibit a wide range CO2 binding strengths, from strongly CO2 binding to nonspontaneous. This observation suggests that the ΔGbind of imidazol(in)ium-based carbenes is tunable to a desired strength by appropriate structural changes. This work sets the stage for systematic energetic tuning of electrochemically enabled reactive separations.
