Building C-N Bonds in Electrocatalytic CO2 Reduction Reactions

Electrochemical reactions, augmented by catalysis, are promising a new paradigm for treating air and water pollutions and turning pollutants such as CO2 and nitrate into useful chemicals. Albeit widely studied, electroreduction solely from CO2 and H2O has a limited product scope lacking elemental diversity. Integrating heteroatom-containing reactants into electrocatalytic CO2 reduction could expand the chemistry and enable the sustainable synthesis of valuable products, such as organonitrogen compounds, which have widespread applications but typically rely on energy-intensive and fossil-fuel-dependent processes for production. This talk will present our research progress towards building C-N bonds in N-integrated CO2 electroreduction. Combining molecule-nanocarbon hybridization and second-coordination-sphere tailoring, we discovered the first molecular electrocatalyst for CO2-to-methanol conversion in significant yield and stability. The reduction proceeds via formaldehyde, an intermediate potentially reactive to N nucleophiles. Following this path, we developed the first electrosynthesis of methylamine from CO2 and nitrate. This 15-proton 14-electron reduction reaction proceeds via an 8-step catalytic cascade with the spontaneous condensation reaction between the formaldehyde and hydroxylamine intermediates to form the C-N bond. Further, we advanced the chemistry to ethylamine formation and N-methylation reactions, opening the door for our electrocatalytic reactions to be used for organic synthesis using CO2/nitrate as a C1/N1 building block.




Hailiang Wang (Yale University)