Ce3+/Ce4+ Ion Redox Shuttle Stabilized Cuδ+ for Efficient CO2 Electroreduction to C2H4

The CO2 electroreduction reaction has advantages in clean and pollution‐free carbon conversion, but it still faces challenges in carbon utilization efficiency and improving the selectivity of C2+ products. Although the dynamic Cuδ+ state is known to favor the C‐C coupling process, the Cuδ+ species suitable for electrocatalytic reduction of CO2 are difficult to maintain under the conditions of strong reduction and large current. Herein, we propose a Ce doping strategy (Ce/CuOx) to protect the Cuδ+ state in the CO2RR process, which enables a high Faradaic efficiency of 60% for multi‐carbon products (40% for C2H4, 14% for CH3CH2OH, and 6% for CH3COOH), and 25 h stability at ‐1.2 V versus the reversible hydrogen electrode. In‐situ infrared spectroscopy, in‐situ XPS combined with density functional theory calculations reveal that the Cuδ+ is stabilized by the redox ion pairs of Ce, which reduces the energy barrier of *CO coupling, and improves the Faraday efficiency of electrocatalytic CO2 reduction of C2H4. This work provides an idea to make full use of lanthanide variable value metals to maintain the stability of dynamic Cuδ+ state and improve the performance of electrocatalytic CO2 reduction to C2H4.