Design of a Two-Compartment Electrolysis Cell for the Reduction of CO2 to CO in Tetrabutylammonium Perchlorate/Propylene Carbonate for Renewable Electrical Energy Storage

Electrochemical reduction of carbon dioxide (CO2) into carbon monoxide (CO) has attracted much attention because the required electricity may be obtained from renewable energy sources. The obtained CO can be then used as the feedstock to produce liquid fuel or other chemical products. CO2 is a non-polar molecule, and is highly soluble in non-aqueous electrolyte. Therefore, it would be beneficial to perform the electrochemical reduction of CO2 in a non-aqueous solution. In this work, a novel electrolysis cell has been designed for CO2 reduction in non-aqueous solutions. This cell is separated into two compartments by a proton exchange membrane. A CO2-saturated tetrabutylammonium perchlorate (Bu4NClO4)/propylene carbonate (PC) solution is used as the catholyte, and an aqueous 0.1 M sulfuric acid (H2SO4) solution is used as the anolyte. In this electrolysis cell, CO2 reduction proceeds in a non-aqueous solution, and H2O oxidation proceeds in aqueous 0.1 M H2SO4. The proton and electron required for CO2 reduction are provided by the electrochemical splitting of water at the anode. The highest faradaic efficiency of CO formation reaches 91.8% at -3.02 V (vs ferrocene/ferrocenium). During long-term electrolysis, the cathode exhibits high catalytic activity, and deactivation has not been observed. The electrolysis cell designed in this work has promising future uses in the chemical industry. (C) 2016 The Electrochemical Society. All rights reserved.