Quinone-annulated imidazolium salts as dual electrolyte-sorbents for electrochemical capture of carbon dioxide

Abstract

Electro-swing carbon capture is an emerging technology that aims to mitigate increasing concentrations of CO₂ in the atmosphere through the reversible capture and release of CO₂ using applied potentials, rather than heat, as the driving force. Herein, we report the synthesis and characterization of quinone-annulated imidazolium salts that can act as both sorbent and electrolyte in CO₂ capture applications. Through cyclic voltammetry, conductivity measurements, and corroboration by density functional theory (DFT), we report that alkyl substitution of the C2 position of the imidazolium moiety of these salts, along with judicious choice of counterion, is critical for stability of the sorbent. Across several synthetic iterations, we identify a C2-butylated quinone-annulated imidazolium bistriflimide salt that possesses promising CO₂ binding strengths for capture of CO₂ from dilute sources, relatively small potential difference (ΔE) between the voltage needed for capture and release, a relatively high solubility (2.87 M) in anhydrous acetonitrile, and sufficient solution conductivity to operate as its own electrolyte. This work sets the stage for the design of ionic molecular materials that can act as both reactive sorbents and electrolytes that could ultimately allow for organic redox battery-like operation of electro-swing systems.