Polymer-Supported Liquid Layer Electrolyzer Enabled Electrochemical CO₂ Reduction to CO with High Energy Efficiency

The electrochemical conversion of carbon dioxide (CO₂ ) to carbon monoxide (CO) is a favorable approach to reduce CO₂ emission while converting excess sustainable energy to important chemical feedstocks. At high current density (>100 mA cm^-2 ), low energy efficiency (EE) and unaffordable cell cost limit the industrial application of conventional CO₂ electrolyzers. Thus, a crucial and urgent task is to design a new type of CO₂ electrolyzer that can work efficiently at high current density. Here we report a polymer-supported liquid layer (PSL) electrolyzer using polypropylene non-woven fabric as a separator between anode and cathode. Ag based cathode was fed with humid CO₂ and potassium hydroxide was fed to earth-abundant NiFe-based anode. In this configuration, the PSL provided high-pH condition for the cathode reaction and reduced the cell resistance, achieving a high full cell EE over 66 % at 100 mA cm^-2 .