Modulating Oxygen Activity via Cation Doping for Efficient High-Temperature Carbon Dioxide Electrolysis.
basic_science · Level V
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- Record sourced from PubMed, PMID 41766201.
- Also identified by DOI 10.1021/acs.nanolett.5c06238.
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Abstract
High-temperature solid oxide electrolysis cells (SOECs) offer a promising pathway for CO<sub>2</sub>-to-CO conversion yet are hindered by cathode inactivity. This study demonstrates cation doping in Sr<sub>2</sub>Ti<sub>0.8</sub>Fe<sub>1.2</sub>O<sub>6-δ</sub> (STF), specifically forming Sr<sub>2</sub>Ti<sub>0.8</sub>FeNi<sub>0.2</sub>O<sub>6-δ</sub> (STFN) and Sr<sub>2</sub>Ti<sub>0.8</sub>FeCo<sub>0.2</sub>O<sub>6-δ</sub> (STFC), as an effective strategy for modulating oxygen activity and enhancing CO<sub>2</sub> electrolysis performance. The STFC cathode delivers optimal results, achieving a 1.15 A cm<sup>-2</sup> current density, 8.01 mL min<sup>-1</sup> cm<sup>-2</sup> CO production rate, and >99% Faradaic efficiency at 1.6 V and 800 °C. Advanced spectroscopic techniques combined with density functional theory calculations reveal that Co doping increases oxygen activity, evidenced by an upshifted O 2p band center and reduced oxygen vacancy formation energy. Consequently, CO<sub>2</sub> adsorption for carbonate (CO<sub>3</sub><sup>2-</sup>) intermediate formation is facilitated, and the energy barrier for CO generation is reduced. A techno-economic assessment projects a competitive CO production cost of $748 per ton. These insights provide fundamental guidelines for the design of high-activity catalysts in high-temperature electrochemical systems.