Electrocatalysts derived from copper complexes transform CO into C2+ products effectively in a flow cell

Abstract The highest performance flow cells capable of electrolytically converting CO2 into higher value chemicals and fuels pass a concentrated hydroxide electrolyte across the cathode. A major problem for CO2 electrolysis is that this strongly alkaline medium converts the majority of CO2 into unreactive HCO3– and CO32– rather than CO2 reduction reaction (CO2RR) products. The electrolysis of CO (instead of CO2) does not suffer from this same problem because CO does not react with hydroxide. Moreover, CO can be more readily converted into products containing two or more carbon atoms (i.e., C2+ products). While several solid-state electrocatalysts have proven competent at converting CO into C2+ products, we demonstrate here that molecular electrocatalysts are also effective at mediating this transformation in a flow cell. Using a molecular copper phthalocyanine (CuPc) electrocatalyst, CO was electrolyzed into C2+ products at high rates of product formation (i.e., current densities J ≥200 mA/cm2), and at high Faradaic efficiencies for C2+ production (FEC2+; 72% at 200 mA/cm2). These findings present a new class of electrocatalysts for making carbon-neutral chemicals and fuels.