Electroreduction of CO₂ and Quantification in New Transition-Metal-Based Deep Eutectic Solvents Using Single-Atom Ag...

Area of Science:

• Green Chemistry
• Materials Science
• Electrochemistry

Background:

• Deep eutectic solvents (DESs) are recognized for their efficiency in CO2 capture applications.
• Electrocatalysis using single-atom electrocatalysts provides a method for evaluating gas absorption properties of novel solvents.
• Understanding the interfacial behavior of CO2 within DESs is crucial for optimizing capture processes.

Purpose of the Study:

• To investigate the interfacial mechanism, detection, quantification, and coordination modes of CO2 in newly prepared transition-metal-based DESs (TDESs).
• To determine the CO2 absorption capacities of specific TDES formulations, namely ZnCl2/ethanolamine (EA) (1:4) and CoCl2/EA (1:4).
• To elucidate the roles of transition metals and CO2 species at the electrocatalyst interface.

Main Methods:

• Preparation and characterization of transition-metal-based deep eutectic solvents (TDESs).
• Electrocatalytic screening of CO2 absorption capacities using single-atom electrocatalysts.
• Analysis of interfacial phenomena, including CO2 detection, quantification, and coordination mode determination.

Main Results:

• The minimum detection time for CO2 was established at 300 s.
• ZnCl2/EA (1:4) and CoCl2/EA (1:4) TDESs exhibited maximum CO2 absorption capacities of 0.2259 and 0.1440 mmol/L, respectively, after 500 s of CO2 saturation.
• Conceivable CO2 coordination modes with Zn in ZnCl2/EA (1:4) TDESs were identified as η1(C) and η2(O, O).
• Transition metals in TDESs form an interface at the compact layer of the electrocatalyst, with CO2•−/CO2 residing in the diffuse layer.

Conclusions:

• The study successfully determined the interfacial mechanism and coordination modes of CO2 in TDESs for the first time.
• The findings provide a facile method for screening the CO2 capture capacity of DESs and other green solvents.
• This research offers reliable inferences about interfacial phenomena critical for advancing carbon capture technologies.