Abstract
Solid oxide electrolysis cell (SOEC) is a promising energy conversion device for the efficient conversion of CO2 into valuable chemicals by using renewable energy sources. Fe-based perovskite oxides are highly active for CO2 electrochemical reduction as fuel electrodes in SOECs. Herein, high valence cations doped La0.6Sr0.4FeO3-δ oxides (La0.6Sr0.4FeO3-δ, La0.6Sr0.4Fe0.9Sc0.1O3-δ, La0.6Sr0.4Fe0.9Ta0.1O3-δ, La0.6Sr0.4Fe0.9W0.1O3-δ) are used as fuel electrodes in SOECs for CO2 electrolysis, and the crystal structure, electrical conductivity, chemical surface exchange coefficient (Kchem), chemical bulk diffusion coefficient (Dchem) and electrolysis performance are investigated for CO2 electrolysis. In addition, we determine the electrochemical processes on half cells and single cells with La0.6Sr0.4FeO3-δ series fuel electrodes by distribution of relaxation times (DRT) analysis, respectively. The results show that W-doping introduces more highly oxidative oxygen species O22−/O− and decreases the activation energy of lattice oxygen diffusion, thus accelerating the oxygen ion diffusion kinetics. The value of Dchem for La0.6Sr0.4Fe0.9W0.1O3-δ reaches to 4.671 × 10−4cm2 S−1 at 800 °C, and this value is 3.8 times than that of La0.6Sr0.4FeO3-δ (1.216 × 10−4cm2 S−1). DRT analysis indicates the different rate-limiting steps for CO2 reduction reaction (CO2RR) on half cells and single cells, which are the dissociation of carbonate intermediate process on half cells, and the exchange and diffusion of oxygen ions process on single cells. W-doping remarkably improves the oxygen ion transport property, thus enhancing the single cell performance for CO2 electrolysis. The single cell with La0.6Sr0.4Fe0.9W0.1O3-δ fuel electrode demonstrates a high current density of 1.48 A cm−2 at 800 °C and 1.5 V, with the polarization resistance (Rp) of 0.527 Ω cm2 at open circuit voltage (OCV). Meanwhile, the single cell exhibits good stability for 50 h at an applied voltage of 1.2 V. This work reveals the difference in electrochemical processes on half cells and single cells, and provides a strategy to accelerate the CO2RR kinetics of La0.6Sr0.4FeO3-δ-based materials.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
