Role of Ionic Solvents in the Electrocatalytic CO2 Conversion and H2 Evolution Suppression: From Ionic Liquids to Deep Eutectic Solvents

Abstract

AbstractThe ionic solvents, including both ionic liquids (ILs) and deep eutectic solvents (DES), are deeply studied for their potential in the carbon dioxide (CO2) capture and its further electrochemical conversion using different electrocatalysts. The aim of this review is to present and critically compare the role of ILs and DES in the activation of the electrochemical CO2 reduction reaction (CO2RR) and suppression of the hydrogen evolution reaction (HER). Therefore, the most relevant advances in the use of these ionic solvents in CO2RR, either as neat reaction medium or as electrolyte in molecular solvents, have been summarized and discussed. A special focus has been made on comparing the current density, overpotential, faradaic efficiency and products selectivity of the CO2RR in the presence of the ionic solvents and relaying those results with their chemical composition. Herein, the most recent strategies reported in the literature based on the use of either DES or ILs for enhancing the electrocatalytic CO2 conversion are reviewed, and some new perspectives based on immobilized ILs at the electrode surface are discussed.