Stabilizing Oxidation State of Cu via Ce Doping into La₂CuO₄ for Enhanced Electroreduction of CO₂ to Multicarbon Products

Stabilizing oxidation state of Cu (Cu^δ+, δ > 0) sites is the key-enabling issue for electrocatalytic carbon dioxide (CO₂) reduction reaction (eCO₂RR) to multicarbon (C₂₊) products. The present study addresses this challenge by introducing cerium (Ce) doping into La₂CuO₄. The Ce doping facilitates f–d orbital coupling between Ce 4f and Cu 3d orbitals, suppressing electron enrichment around Cu atoms by transferring electrons from Cu 3d orbitals to Ce 4f orbitals via a Cu−O−Ce chain. These changes modulate the electronic structure of Cu, reduce the distance between neighboring Cu atoms, optimize the binding energy of surface-adsorbed CO (*CO), and lower the reaction energy barrier for *CO dimerization. As a result, the La_1.95Ce_0.05CuO₄ catalyst achieves a Faradaic efficiency up to 81% for C₂₊ products and maintains high stability over 50 h operation. This work highlights the unique role of Ce doping in stabilizing Cu^δ+ sites and hence enhancing C−C coupling, providing a pathway for designing efficient catalysts for eCO₂RR.