High rate, selective, and stable electroreduction of co₂ to co in basic and neutral media

The electroreduction of carbon dioxide (CO₂) to chemicals such as carbon monoxide (CO) shows great potential for renewable fuel and chemical production. Significant progress in individual performance metrics such as reaction rate, selectivity, and stability has been achieved, yet the simultaneous achievement of each of these key metrics within a single system, and in a wide range of operating conditions, has yet to be demonstrated. Here we report a composite multilayered porous electrode consisting of a polytetrafluoroethylene gas distribution layer, a conformal Ag catalyst, and a carbon current distributor. Separating the gas and current distribution functions provides endurance, and further reconstructing the catalyst to carbonate-derived Ag provides flexibility in terms of electrolyte. The resulting electrodes reduce CO₂ to CO with a Faradaic efficiency over 90% at current densities above 150 mA/cm², in both neutral and alkaline media for over 100 h of operation. This represents an important step toward the deployment of CO₂ electroduction systems using electrolyzer technologies.