Non-perovskite Structural CaFe₂O₄ with Matched Thermal Expansion Coefficients Exhibiting High Performance for CO₂ Electroreduction

Abstract

Electroreduction of CO 2 in solid oxide electrolysis cells is a promising way to convert CO 2 to value-added chemicals using renewable electricity. However, the traditional perovskite cathodes suffer from low activity or mismatched thermal expansion coefficients (TECs) compared with other components of cells. Here, a non-perovskite cathode CaFe 2 O 4 that has a matching TEC with other components of the cell was investigated for CO 2 electrolysis in solid oxide electrolysis cells. CaFe 2 O 4 undergoes phase transition under electroreduction conditions, producing brownmillerite-structured Ca 2 Fe 2 O 5 with abundant oxygen vacancies and electro-exsolved Fe nanoparticles, forming active metal/oxide interfaces. The phase transition improves the CO 2 adsorption and conductivity and thus promotes the activation of CO 2 and electronic transfer. Therefore, this cathode demonstrates high electrochemical performance, reaching a current density of 1.81 A cm −2 at 1.6 V and 850 °C, and exhibits good stability at 1.2 V and 850 °C for 325 h. The cathode connects well with other components of cells even after the longterm stability test due to the matching TEC.

High-Performance Reversible Solid Oxide Cells for Powering Electric Vehicles, Long-Term Energy Storage, and CO2 Conversion

“…As shown in Figure A, current densities of −3.4, −2.9, −2.2, and −1.3 A cm –2 are attained at 750, 700, 650, and 600 °C, respectively. Such performances are so superior when compared to the existing literature results, with the additional advantage of significantly lower operating temperatures that are crucial to circumvent the degradation issue and reduce the electricity consumption. ,,,− Additionally, no visible coking was observed after the electrochemical characterization, indicating a satisfactory selectivity toward CO. The EIS analysis offers valuable insights into the exceptional performance observed.…”

Structure-evolved YbBiO3perovskites for highly formate-selective CO2electroreduction

“…49,50 The structureevolved YbBiO 3 perovskite with the interfaces of metal nanoparticles/perovskite optimized the charge transfer on the catalyst surface and the stability of the key intermediates, thus advancing the ERCO 2 . [51][52][53] Taken together, the Bi/YbBiO 3 heterostructure promoted the formation and stability of CO 2 * − intermediates, which could help optimize the crucial steps of ERCO 2 , thus facilitating faster kinetics for formate generation. 54…”