Ceria is a promising material for cathodes in high-temperature CO2 electrolysis cells because ceria can become a mixed electronic and ionic conductor through doping, which enables a high surface area for electrocatalysis. Here, we systemically investigate the effect of strain to enhance the activity for electrocatalytic CO2RR on CeO2(111) using density functional theory corrected for on-site Coulomb interactions (DFT + U).
We find that tensile strain decreases the oxygen vacancy formation energy due to a downshift of the Ce 4f orbital energy, in agreement with the larger size of the Ce3+ ion than the Ce4+ ion. The corresponding upshift in the Ce f-band center with compressive strain destabilizes the formation energy of the critical surface oxygen vacancies and reduces the energetic span of the reduction reaction, leading to a 4 orders of magnitude higher turnover frequency at 800 K for 4% compressive strain. These findings shed new light on possible pathways to enhance the catalytic activity for CO2RR on CeO2(111) and related catalytic systems by strain engineering.
Jens Vive Kildgaard, Heine A. Hansen, and Tejs Vegge
J. Phys. Chem. C 2021, 125, 26, 14221–14227
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