The CO2/CO electroreduction reaction (CO2RR/CORR) to liquid products presents an enticing pathway to store intermittent renewable electricity. However, the selectivity for desirable high-value C3 products, such as n-propanol, remains unsatisfactory in CO2RR/CORR. Here, we report that *CO enrichment and proton regulation cooperatively enhance C1-C2 coupling by increasing CO pressure and utilizing proton sponge modification, promoting the production of n-propanol over a Cu0/Cu⁺ nanosheet catalyst in the CORR. We obtain an impressive Faradaic efficiency (FE) of 44.0% ± 2.3% for n-propanol at a low potential of −0.44 V vs. reversible hydrogen electrode (RHE) under 3 bar CO. Experimental results demonstrated that *H intermediates could be regulated by proton sponge modification. In situ characterizations combined with density functional theory (DFT) calculations validate that Cu+ species exist stably in proton sponge-modified Cu-based catalysts along with appropriate *CO coverage. This design facilitates the potential-determining C1-C1 and C1-C2 coupling steps and contributes to the n-propanol production.
