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

Abstract

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.