With pure CO 3 2-transfer, the maximum CO2 single pass conversion, 𝑆𝑃, is limited to 50%, as 2 molecules CO2 are consumed for each produced CO. Under these conditions, the NiNC-IMI cell (1 mg cm -2 ) 𝑆𝑃 reaches the very high single pass conversion of 40% at -300 mA cm -2 , at a previously unachieved low stoich = 1.2 (Figure ). As a result, our NiNC-IMI electrolyzer design delivers a CO concentrated exit stream.