Assessing the Kinetics of Quinone–CO₂ Adduct Formation for Electrochemically Mediated Carbon Capture

Abstract

Carbon capture driven by renewable electricity represents a promising approach to mitigate carbon dioxide (CO 2 ) emissions and combat climate change. Electrochemically mediated carbon capture can be achieved by developing redox-active Lewis bases, with quinones being the most representative chemistry. In aprotic electrolytes, a subset of quinoid species can selectively uptake CO 2 from a dilute feed upon electro-reduction via a nucleophilic addition reaction and release a concentrated CO 2 product stream upon oxidation. However, there is a lack of quantitative understanding of the reaction kinetics landscape of redox-active CO 2 sorbents, especially considering the complex nature of the multi-component electrolyte media they must be deployed in. To bridge this knowledge gap, we investigate the bimolecular reaction rate constant between CO 2 and radical anions of various quinones in a range of electrolytes using an electroanalytical technique. Combined with molecular dynamics and density functional theory calculations, we provide insights into the complex interplay between quinone chemistry, supporting salt composition, and electrolyte solvents on the intrinsic CO 2 adduct formation kinetics. To summarize some key observations, we found that the reaction rate is affected by both the identity and concentration of the cationic and anionic species in the supporting electrolyte, the presence of hydrogen-bonding additives may accelerate the kinetics, and orthoisomers of quinones have a faster reaction rate than para-isomers. We believe the work can help guide the rational design of electrochemical microenvironments for enhanced electrochemically mediated carbon capture performance.

Aggregation and Capacity Limiting Effects in Anthraquinone-Based Flow Battery Negolytes

“…4) reflects the binding strength of CO 2 on the hydroquinone moiety. 38 The results indicate that CO 2 forms a stronger bond with AQDS than DBEAQ, reflected in the greater shift of the second one-electron reoxidation process for AQDS than for DBEAQ.…”

“…Carbonate and bicarbonate ions are in equilibrium with CO 2 in solution yielding an increasing amount of CO 2 when the pH approaches or dips below the pKa value of HCO 3 − (pKa = 8.2). 38 The effect of the formation of CO 2 during the acidification of the carbonate solution and subsequent binding to the anthraquinone can be seen on the red voltammetric traces in Fig. 3.…”

“…CO 2 has been shown to bind on the hydroxyl moiety of hydroquinones, forming a CO 2 adduct, and altering the electrochemical response of the quinone. 38 In the case of AQDS and DBEAQ the concerted two-electron re-oxidation process that is normally seen in aqueous electrolyte, splits into two distinct one electron oxidation steps when the solution is purged with CO 2 (Fig. 3, blue plots).…”

Probing the role of acid site distribution on water structure in aluminosilicate zeolites: insights from molecular dynamics

“…Zeolites are nanoporous solids characterized by high crystallinity and hydrothermal stability that have been studied extensively due in part to their role as catalysts and sorbents for the petrochemical industry, [1][2][3][4][5] environmental remediation, [6][7][8][9][10][11] , and sustainable chemical synthesis. [12][13][14] Notably, aluminosilicate zeolites possess anionic lattice charges resulting from aluminum heteroatom substitutions that are balanced by cations such as protons, which can function as catalytic active sites.…”