Ce 3+ /Ce 4+ Ion Redox Shuttle Stabilized Cu δ+ for Efficient CO 2 Electroreduction to C 2 H 4

The CO 2 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 C 2 products. Although the dynamic Cu δ+ state is known to favor the C−C coupling process, the suitable Cu δ+ species for electrocatalytic reduction of CO 2 are difficult to maintain under the conditions of strong reduction and large current. Herein, we propose a Ce doping strategy to stabilize the Cu δ+ state (Ce/CuO x ) during the CO 2 RR process, which enables a high Faradaic efficiency of 60 % for multi‐carbon products (40 % for C 2 H 4 , 14 % for CH 3 CH 2 OH, and 6 % for CH 3 COOH), and 25 h stability at −1.2 V versus the reversible hydrogen electrode. In situ infrared spectroscopy, in situ X‐ray photoelectron spectroscopy combined with density functional theory calculations reveal that the Cu δ+ is stabilized by the redox ion pairs of Ce, which reduces the energy barrier of *CO coupling, and improves the Faraday efficiency of electrocatalytic CO 2 reduction of C 2 H 4 . This work provides a new idea to make full use of lanthanide variable value metals for advanced catalysis and clean energy conversion.