Rare-earth doping of CeO₂ for enhanced high-temperature CO₂ electrolysis: balancing activity and carbon tolerance

CeO₂ exhibits promising carbon tolerance for high-temperature CO₂ electrolysis in solid-oxide electrochemical cells; however, its low CO production activity remains a critical bottleneck. In this study, theoretical calculations were performed to explore how La, Pr, Sm, Gd, Lu, and Bi doping balances the activity and carbon tolerance over the CeO₂(111) surface. Results indicate that La, Sm, and Lu doping achieve highly active and selective CO₂-to-CO conversion. Specifically, Sm doping reduced the barrier for the first C−O dissociation (to CO) by 0.64 eV while significantly increasing the barrier for the second C−O cleavage (to carbon) by 1.87 eV. This synergetic effect enhanced CO production while effectively suppressing carbon deposition. Moreover, the ionic radius of dopants and the oxygen vacancy formation energy can serve as effective descriptors for predicting activity and carbon tolerance. This work provides mechanistic guidance for the rational design of coke-resistant electrodes for efficient carbon capture and utilization technologies.