Electroreduction of CO2and Quantification in New Transition-Metal-Based Deep Eutectic Solvents Using Single-Atom Ag Electrocatalyst

Abstract

Deep eutectic solvents (DESs) are efficient media for CO2capture, and an electroreduction process using the deterministic surface of single-atom electrocatalysts is a facile way to screen gas absorption capacities of novel DESs. Using newly prepared transition-metal-based DESs indexed as TDESs, the interfacial mechanism, detection, quantification, and coordination modes of CO2were determined for the first time. The CO2has a minimum detection time of 300 s, whereas 500 s of continous ambient CO2saturation provided ZnCl2/ethanolamine (EA) (1:4) and CoCl2/EA (1:4) TDESs with a maximum CO2absorption capacity of 0.2259 and 0.1440 mmol/L, respectively. The results indicated that CO2coordination modes of η1(C) and η2(O, O) with Zn in ZnCl2/EA (1:4) TDESs are conceivable. We found that the transition metals in TDESs form an interface at the compact layer of the electrocatalyst, while CO2•-/CO2reside in the diffuse layer. These findings are important because they provide reliable inferences about interfacial phenomena for facile screening of CO2capture capacity of DESs or other green solvents.