High-Efficiency Conversion of CO ₂ to Oxalate in Water Is Possible Using a Cr-Ga Oxide Electrocatalyst

Electrochemical transformation of CO ₂ into commodity chemicals such as oxalate is a strategy for profitably remediating high atmospheric CO ₂ levels. Electrocatalysts for oxalate generation, however, have required prohibitively large applied potentials, forcing the use of nonaqueous electrolytes. Here, a thin film comprised of alloyed Cr and Ga oxides on glassy carbon is shown to electrocatalytically generate oxalate from aqueous CO ₂ with high Faradaic efficiencies at 690 mV overpotential. Oxalate is produced at a surface anion site via a CO-dependent pathway; the process is highly sensitive to the hydrogen-bonding environment and avoids the commonly invoked CO ₂ ^•- intermediate. Ultimately, this catalytic system accomplishes efficient CO ₂ to oxalate conversion in protic electrolyte.