Efficient upgrading of CO to C₃ fuel using asymmetric C-C coupling active sites

The electroreduction of C₁ feedgas to high-energy-density fuels provides an attractive avenue to the storage of renewable electricity. Much progress has been made to improve selectivity to C₁ and C₂ products, however, the selectivity to desirable high-energy-density C₃ products remains relatively low. We reason that C₃ electrosynthesis relies on a higher-order reaction pathway that requires the formation of multiple carbon-carbon (C-C) bonds, and thus pursue a strategy explicitly designed to couple C₂ with C₁ intermediates. We develop an approach wherein neighboring copper atoms having distinct electronic structures interact with two adsorbates to catalyze an asymmetric reaction. We achieve a record n-propanol Faradaic efficiency (FE) of (33 ± 1)% with a conversion rate of (4.5 ± 0.1) mA cm^-2, and a record n-propanol cathodic energy conversion efficiency (EE_{cathodic half-cell}) of 21%. The FE and EE_{cathodic half-cell} represent a 1.3× improvement relative to previously-published CO-to-n-propanol electroreduction reports.