The renewable-energy-powered electrocatalytic conversion of carbon dioxide and carbon monoxide into carbon-based fuels provides a means for the storage of renewable energy. We sought to convert carbon monoxide—an increasingly available and low-cost feedstock that could benefit from an energy-efficient upgrade in value—into n-propanol, an alcohol that can be directly used as engine fuel. Here we report that a catalyst consisting of highly fragmented copper structures can bring C 1 and C 2 binding sites together, and thereby promote further coupling of these intermediates into n-propanol. Using this strategy, we achieved an n-propanol selectivity of 20% Faradaic efficiency at a low potential of −0.45 V versus the reversible hydrogen electrode (ohmic corrected) with a full-cell energetic efficiency of 10.8%. We achieved a high reaction rate that corresponds to a partial current density of 8.5 mA cm –2 for n-propanol.