Electrocatalytic C─C Coupling of Dimethyl Oxalate to C 4 Dicarboxylate on Cu

ABSTRACT Electrocatalytic conversion of CO to value‐added multi‐carbon chemicals enables carbon resource recycling and emission reduction. Building on the industrial process of dimethyl oxalate (DMO) production from CO and methanol, we report in this work a selective electrochemical pathway to convert DMO to dimethyl tartarate (DMT), a precursor to multiple C 4 ‐dicarboxylic acids. On a Cu α catalyst dominated by Cu(111)‐like sites, Faradaic efficiency and partial current density for DMT reach 74.7% and 152 mA/cm − 2 , respectively, which significantly outperforms Cu β dominated with Cu(100)/(110)‐like sites. Facet dependence of the C─C coupling is confirmed via reactivity tests on single‐crystal Cu surfaces and CO‐poison experiments. In situ Raman spectroscopy reveals that DMO adopts distinct adsorption configurations on different Cu facets—planar on Cu(111) and upright on Cu(100)/(110)—accounting for the selectivity difference of DMT. Mechanistic studies indicate a surface‐mediated nonradical pathway, with the initial electron transfer to adsorbed DMO as the rate‐determining step for DMT formation. Our work enables the production of C 4 ‐dicarboxylic acids via cascade reactions with CO as the initial feedstock.