Issue 20, 2023

Carbon dioxide reduction processes on a samarium doped ceria electrocatalyst with exsolved Fe particles

Abstract

Solid oxide electrolysis cells (SOECs) can efficiently convert CO2 into valuable chemicals. As a potential cathode material, ceria has abundant oxygen vacancies, which are essential for the CO2 reduction reaction (CO2RR). Its electrochemical performance can be significantly improved by forming Fe nanoparticles on the ceria surface through an exsolution reaction. However, the detailed effects of Fe exsolution on the CO2RR are not well understood. Here, we use density functional theory (DFT) methods to simulate the processes of the CO2RR on samarium-doped ceria (SDC) surfaces with exsolved Fe clusters. Fe exsolution reduces the surface oxygen vacancy formation energy and enhances CO2 adsorption energy. The exsolution forms an Fe–O–Ce structure, which reduces the energy barrier for the CO2RR. Transition state calculations indicate that the CO2RR on SDC is limited by CO2 dissociation with an energy barrier of 3.71 eV, while with exsolved Fe13 clusters, it is limited by CO desorption with a barrier of 1.09 eV. At 800 °C, CO2 dissociation on SDC is the rate-determining step with a slower elementary reaction rate of 1.24 × 102 s−1, but Fe partial exsolution changes it to CO desorption with a much faster rate of 9.02 × 107 s−1. The electrical conductivity relaxation test shows that kchem of Fe-SDC at 700 °C is 2.5 times higher than that of SDC, and its activation energy is 0.91 eV, much lower than that of SDC (1.43 eV). These suggest that Fe partially exsolved SDC has strongly enhanced catalytic properties, which are consistent with DFT calculations.

Graphical abstract: Carbon dioxide reduction processes on a samarium doped ceria electrocatalyst with exsolved Fe particles

Supplementary files

Article information

Article type
Paper
Submitted
13 Mar 2023
Accepted
18 Apr 2023
First published
19 Apr 2023

J. Mater. Chem. A, 2023,11, 10646-10658

Carbon dioxide reduction processes on a samarium doped ceria electrocatalyst with exsolved Fe particles

L. Ye, K. Zhu, Y. Jiang, S. Zhang, R. Peng and C. Xia, J. Mater. Chem. A, 2023, 11, 10646 DOI: 10.1039/D3TA01519J

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