Abstract The electroreduction of C 1 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 C 1 and C 2 products, however, the selectivity to desirable high-energy-density C 3 products remains relatively low. We reason that C 3 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 C 2 with C 1 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.