Ce4+-Doped CuO Mesoporous Nanosheets for CO2 Electroreduction to C2H6 with High Selectivity under a Wide Potential Window in a Flow Cell

CO2 electrocatalytic reduction (CO2ER) to multiple carbonous products is a valuably sustainable way to obtain fuels and chemicals. However, its practical application is still hindered by low selectivity and activity under large current density. A flow cell enables CO2ER to operate at high current densities by mitigating the CO2 mass transport limitation issue. Here, we report Ce4+-doped CuO mesoporous nanosheets affording high selectivity and activity toward CO2ER to C2H6 in a flow cell. Ce4+ doping induces oxygen vacancies and modulates the electron distribution of CuO, which enhances the adsorption intensity and coverage of a *CO intermediate for further C–C coupling to finally produce C2H6. Moreover, Ce4+ doping can well protect Cu2+ species from being reduced during CO2ER, which guarantees high selectivity and stability for C2H6 generation. As a result, the optimal Ce0.03Cu0.97O0.83 exhibits large partial current densities of 55.3 ± 1.6–235.5 ± 4.3 mA cm–2 with Faradaic efficiencies over 50% for ethane under a wide potential window of −0.5 to −0.9 V in a flow cell. This work clarifies that the CuO nanostructure doped with lanthanide metal ions can modulate the reaction pathway of CO2ER to C2H6 in a flow cell.