Abstract
Bicarbonate electrolysers convert aqueous carbon capture solutions enriched with bicarbonate into carbon products, such as CO, while generating hydroxide for further reaction with waste CO2. Here, we report a bicarbonate electrolyser that uses a free-standing porous silver electrode rather than a composite carbon electrode widely used in gas-fed CO2 electrolysers. This free-standing metal electrode is easier to fabricate, more hydrophilic, more durable, and more resistant to impurities common to carbon capture solutions. These properties enable efficient electrolysis of 3.0 M bicarbonate solutions into CO, reaching faradaic efficiencies for CO production of 59% at 100 mA cm–2 under ambient pressure and 95% at 100 mA cm–2 under 4 atm of pressure. These performance metrics are comparable to those of gas-fed CO2 electrolysers and show that free-standing porous metal electrodes can benefit integrated carbon capture and electrochemical CO2 utilization schemes.