Cathodic Carbon Chemically Adsorbs Carbon Dioxide: Why Is it True?

TL;DR

This paper proposes a novel method for capturing CO2 using negatively-charged carbon structures, validated through simulations with graphene quantum dots, suggesting potential for new CO2 sorbent materials in CCS technologies.

Contribution

Introduces a new chemical absorption mechanism of CO2 via negatively-charged carbon structures, supported by simulation data, indicating a promising direction for CO2 capture materials.

Findings

Negatively charged GQD reacts with CO2 to form carboxylated GQD.

Activation energy for the reaction is 60 kJ/mol, competitive with existing methods.

Energy effect of the reaction is -55 kJ/mol, indicating favorable chemisorption.

Abstract

Large-scale applications are waiting for an optimal CO2 scavenger to reinforce CCS and CCU technologies. We herein introduce and succinctly validate a new philosophy of capturing gaseous CO2 by negatively-charged carbonaceous structures. The chemical absorption of CO2 turns out possible thanks to the emergence of significant nucleophilic interaction carbon centers upon applying voltage. The carbonaceous cathode, therefore, may serve as a prototype of a new CO2 sorbent. As a model to simulate chemisorption, we used a small-sized graphene quantum dot (GQD). According to the recorded reaction profiles, the negatively charged GQD containing 16 carbon atoms readily reacts with the CO2 molecule and produces carboxylated GQD. In turn, the activation energy (60 kJ/mol) and energy effect (-55 kJ/mol) for the reaction in water appeared surprisingly competitive in the context of the literature. We hypothesize that the carbonaceous cathode deserves in-depth experimental research as a possible CO2 chemical sorbent. Despite we used GQD for simulations, the encouraging results can be extrapolated to other nanoscale carbons and, more importantly, to the activated carbon species widely employed in modern electrochemical devices.