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.