Sulfite-Assisted Acetate Conversion from CO Electroreduction

The efficient acetate conversion from CO electroreduction is challenging due to the poor selectivity at high reaction rate, which requires the competition with H₂ and other C₂₊ (i. e., ethylene, ethanol, n-propanol) reduction products. Electrolyte engineering is one of the efficient strategies to regulate the reaction microenvironment. In this work, the adding of sulfite (SO₃ ^2-) with high nucleophilicity in KOH electrolytes was demonstrated to enable improving the CO-to-acetate conversion via generating a S-O chemical bond between SO₃ ^2- and oxygenated *C₂ intermediates (i. e., *CO-CO, *CO-COH) compared with that in pure KOH system on both synthesized Cu(200)- and normal commercial Cu(111)-facets-exposed metallic Cu catalysts. As a result, the prepared Cu(200)-facets-exposed metallic Cu catalyst with surface ions modification showed an superior Faradaic efficiency of 63.6 % at -0.6 A ⋅ cm^-2, and extraordinary absolute value of peak partial current density as high as 1.52 A ⋅ cm^-2 with adding SO₃ ^2- in KOH electrolytes, compared to the best reported values in both CO and CO₂ electroreduction. Our work suggests an attractive strategy to introduce the oxyanion with high nucleophilicity in electrolytes to regulate the microenvironment for industrial-current-density electrosynthesis of acetate from CO electroreduction.