Carbon dioxide reduction on the composite of copper and praseodymium-doped ceria electrode in a solid oxide electrolysis cells
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Electrochemical reduction of CO2 is performed in a solid oxide electrolysis cell (SOEC), with Cu-Pr0.1Ce0.9O2-δ (Cu-PDC) composite cathode and La0.8Sr0.2MnO3-δ (LSM) anode on yttria-stabilized zirconia (YSZ) electrolyte. The electrochemical performance of the fabricated SOEC for CO2 reduction is compared with a similar high-temperature SOEC having Cu-infiltrated praseodymium-doped ceria electrode (Neetu et al., ECS Transaction 78, 3329, 2017). On varying the applied potentials and reducing environment at different volumetric ratio of CO2/CO and CO2/H2, electrochemical measurements are carried out to understand the role of reducing atmosphere. On the Cu-PDC composite electrode, a significantly improved reduction current (− 0.84 A cm−2 at Vapp = 2.5 V) is measured as compared to the Cu-infiltrated electrode reported earlier. Oxygen vacancy formation energy on doped ceria surface is calculated, using density functional theory, and found to be relatively lower (∆Evac = 84.6 kJ mole−1) as compared to the un-doped ceria surface (∆Evac = 152.8 kJ mole−1), indicating facile oxygen anion transport in Cu-PDC. Density of state calculations shows Pr substitution in ceria responsible for the reduction in band gap [O(2p) → Ce(4f)] from 1.75 to 0.4 eV, contributing to electronic conduction. The theoretical results thus elucidate the activity of Pr-doped ceria materials for CO2 reduction to CO. The theoretical results combined with experiments conducted on Cu-PDC electrode are therefore expected to provide a basis for the development of a new electrocatalyst for CO2 reduction.
KeywordsCarbon dioxide reduction Electrocatalyst Ceria Solid oxide electrolysis Density functional theory
We acknowledge the computer service center of Indian Institute of Technology, for providing the high-performance computing systems (HPC). We acknowledge Dr. Manish Agrawal, Dr. Nishant Sinha, and Uzma Anjum for their help in DFT calculations.
This study is financially supported by GAIL R&D and Department of Science and Technology (DST), Government of India.
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