Efficient electrocatalytic reduction of CO2 at Ag catalyst in 1-ethyl-3methylimidazolium ethylsulfate and its co-catalytic role as supporting electrolyte during the reduction in acetonitrile medium

Sayyar Muhammad ¹ Asad Ali ^2*

• ¹ Islamia College University, Peshawar, Khyber Pakhtunkhwa, Pakistan
• ² Luleå University of Technology, Luleå, Sweden

CO2 electrochemical reduction reaction (CO2ERR) have shown great promise in reducing greenhouse gas emissions while also producing useful chemicals. In this contribution, we describe the CO2ERR at different catalysts using 1-ethyl-3-methylimidazolium ethyl sulfate [emim][EtSO4] ionic liquid (IL) as a solvent and as a supporting electrolyte. CO2ERR occurs at Ag and Cu catalysts at a lower overpotential as compared to that at Au, Pt and boron doped diamond (BDD) catalysts. Also, we report that ILs play a better co-catalytic role when used as a supporting electrolyte during CO2ERR in acetonitrile (AcN) medium as compared to the conventional supporting electrolyte, tetrabutylammonium hexafluorophosphate [TBA][PF6] in AcN. Further, it is found that imidazolium-based cations ([emim] + ) play a significant cocatalytic role during the reduction compared to [TBA] + and pyrrolidinium [empyrr] + cations while anions of the ILs play no such role. The formation of CO from the CO2ERR was detected during using cyclic voltammetry at Ag catalyst both in [emim][EtSO4] as well as in AcN solvent containing [emim][EtSO4] as supporting electrolyte. The product of the CO2 reduction in this IL medium at Ag catalyst is CO which can be converted to synthetic liquid fuels by coupling the process with the Fischer-Tropsch process or through the conversion of CO2 into fuels based on green hydrogen by the Sabatier process i.e. methanation of CO2 on industrial scale in the future.