CO₂ Electroreduction from Carbonate Electrolyte

The process of CO₂ valorization-from capture of CO₂ to its electrochemical upgrade-requires significant inputs in each of the capture, upgrade, and separation steps. Here we report an electrolyzer that upgrades carbonate electrolyte from CO₂ capture solution to syngas, achieving 100% carbon utilization across the system. A bipolar membrane is used to produce proton in situ to facilitate CO₂ release at the membrane:catalyst interface from the carbonate solution. Using a Ag catalyst, we generate syngas at a 3:1 H₂:CO ratio, and the product is not diluted by CO₂ at the gas outlet; we generate this pure syngas product stream at a current density of 150 mA/cm² and an energy efficiency of 35%. The carbonate-to-syngas system is stable under a continuous 145 h of catalytic operation. The work demonstrates the benefits of coupling CO₂ electrolysis with a CO₂ capture electrolyte on the path to practicable CO₂ conversion technologies.