In situ techniques for aqueous quinone-mediated electrochemical carbon capture and release

Abstract

Here we elucidate the intricate interplay between the nucleophilicity swing and pH swing mechanisms in aqueous quinone-mediated carbon capture systems, showcasing the critical role of understanding this interplay in the material discovery cycle. This insight prompts the development of two in situ techniques. The first technique employs in situ reference electrodes and capitalizes on discernible voltage signature differences between quinones and quinone–CO2 adducts, allowing for the quantification of the isolated contributions of the two mechanisms. The second method is developed based on our finding that the adduct form of the quinone exhibits a fluorescence emission from an incident light at wavelengths distinct from the fluorescence of the reduced form. Thus, we introduce a noninvasive, in situ approach using fluorescence microscopy, providing the capability to distinguish species with subsecond time resolution at single-digit micrometer resolution. This technique holds promise for studying quinone-based systems for carbon capture and beyond. In an aqueous quinone-mediated system, both pH swing and nucleophilicity swing mechanisms contribute to CO2 capture, but traditional measurement methods report only the combined contributions, without quantifying their relative contributions. Here the authors introduce thermodynamic and kinetic analyses coupled with two in situ experimental techniques to quantify the contributions of these mechanisms.