Abstract CO2 electrochemical reduction reactions (CO2ERR) has 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 than that at Au, Pt, and boron-doped diamond (BDD) catalysts. In addition, we report..