Highly dispersed Cu-CuO-CeO interfaces on reduced graphene oxide for CO electroreduction to C products.

The Cu-Cu interfaces play a key role in the electrochemical CO reduction reaction (CORR) to produce multi-carbon products (C), however, it is difficult for Cu to exist stably under reducing conditions. Herein, we construct highly dispersed and stable Cu-CuO-CeO interface on reduced graphene oxide (rGO) for CO electroreduction to C products. During the synthesis process, utilizing strong electrostatic interactions, the complex ions of Cu and Ce are uniformly adsorbed on the surface of graphene oxide. Then, under the solvothermal reaction of ethylene glycol and thiourea, the two metal complex ions are converted into highly dispersed and ultrafine CuS-CeO nanocomposites on rGO. Interestingly, CeO and thiourea synergistically regulate the generation of only Cu. Under the CORR process, the reconstruction of CuS promotes the formation of Cu and CuO species. CeO stabilizes partial Cu species and promotes the formation of Cu-CuO-CeO composite interface. With the help of synergistic effect of Cu, Cu and CeO, the optimized reaction interface achieves the Faradaic efficiency (FE) of 74.5 % for C products with the current density of 230 mA cm at -0.9 V versus the reversible hydrogen electrode. In situ attenuate total reflectance-infrared absorption spectroscopy (ATR-IRAS) spectra show that the composite interfaces promote the adsorption and activation of HO and CO, improve the surface coverage of CO intermediates (*CO), and thus accelerate the CC coupling process.