Search

Proton ceramic fuel cells (PCFCs) are gaining attention due to their high energy conversion efficiency. However, the development of PCFCs is hindered by the lack of efficient and robust cathode materials. This article proposes a solution by introducing certain cationic deficiency into the Ba 0.9 La 0.1 Co 0.7 Fe 0.2 Nb 0.1 O 3-δ (BLCFN) cathode matrix, which results in abundance of oxygen vacancies as well as enhanced proton defects. Consequently, the catalytic activity and hydration activity of the BLCFN oxygen electrode are improved during the reduction reaction process. Specifically, the polarization impedance (R p) of the (Ba 0.9 La 0.1) 0.95 Co 0.7 Fe 0.2 Nb 0.1 O 3-δ (BL95CFN) decreases by 20% compared to the pristine BLCFN, reaching 0.12 Ω·cm2 at 700 °C in air. The R p of BL95CFN decreases by 12% in a steam environment of 20 vol%. This enhancement is attributed to the higher concentration of oxygen vacancies, which leads to an improved proton diffusion rate and hydration performance. The peak power density of the anode-supported BL95CFN | BZCYYb | BZCYYb-NiO single cell reaches 641 mW cm−2 at 700 °C, and the performance of this single cell remains stable for nearly 100 h. These findings highlight the vital role of adjusting oxygen vacancy and proton diffusion, providing a feasible strategy for improving the performance and stability of PCFC cathode materials. • An A-site deficiency engineered Ba 0.9 La 0.1 Co 0.7 Fe 0.2 Nb 0.1 O 3-δ cathode is proposed. • A-site deficiency greatly enhanced ORR activity of Ba 0.9 La 0.1 Co 0.7 Fe 0.2 Nb 0.1 O 3-δ. • Oxygen vacancy by introducing cationic defects, enhances catalytic activity and hydration reaction activity. • (Ba 0.9 La 0.1) 0.95 Co 0.7 Fe 0.2 Nb 0.1 O 3-δ cathode showed good long-term stability. [ABSTRACT FROM AUTHOR]

Highly efficient and stable cathodes are significantly vital for solid oxide fuel cells (SOFCs). However, one of key impediment to the cathode development is the undesirable oxygen reduction activity and stability with exposure upon steam. Herein, we present a novel nanoparticles-decorated cathode, comprised of O2−/e−/H+ triple-conducting K+-doped BaCo 0.7 Fe 0.2 Y 0.1 O 3-δ (Ba 0.9 K 0.1 Co 0.7 Fe 0.2 Y 0.1 O 3-δ , BKCFY) matrix oxide and the mixed O2−/e− conducting nanoparticles of BaCoO 3-δ (BCO) through water-mediated exsolution process, exhibiting high activity and robust stability with exposure upon the steam. The cathode shows a low polarization resistance of 0.048 Ω cm2 at 700 °C when exposed upon humid air with 3% H 2 O, approximately 24% lower than that in dry air (0.065 Ω cm2 at 700 °C). Such improvement is mainly ascribed to the exsolved BaCoO 3- δ nanoparticles decorated on the porous BKCFY, which enlarged the triple phase boundary for oxygen reduction reaction. The increased oxygen vacancy concentration through K doping can accelerate the Ba and Co ions segregation to form BaCoO 3-δ with exposure upon the wet condition. Furthermore, K+ dopant with higher basicity than Ba2+ is beneficial for hydration behavior, which effectively promotes the catalytic activity under the water vapor. Moreover, the exsolved BaCoO 3-δ nanoparticles are socketed on the BKCFY matrix oxide, which ensures high stability for this hybrid cathode operated at 700 °C. The findings provide a promising approach to design the triple-conducting cathode for solid oxide fuel cells via water-mediated exsolution, which can also be applied for solid oxide electrolysis cells and membrane reactors. [Display omitted] [ABSTRACT FROM AUTHOR]

The significant challenges facing the development of the cathode for intermediate-temperature solid oxide fuel cells (IT-SOFCs) are the poor oxygen reduction reaction (ORR) activity as well as the CO 2 poisoning issues. Herein, an La/Nb co-doped perovskite Ba 0.9 La 0.1 Co 0.7 Fe 0.2 Nb 0.1 O 3- δ (BLCFN) has been developed as a promising cathode for IT-SOFCs. The polarization resistance of BLCFN cathode is 0.073 Ω cm2 at 700 °C air. This remarkable improved ORR activity can be attributed to the increased oxygen vacancies caused by the introduction of La3+ and Nb5+ ions. Furthermore, the collaboration introduction of La3+ and Nb5+ ions greatly reduce the alkalinity of the BLCFN electrode, bringing excellent CO 2 -tolerance for BLCFN cathode. No carbonate is yielded on the surface of the BLCFN cathode. The improvement on CO 2 -tolerance for these cathodes is largely attributed to the introduction of Nb5+ ions, which have higher acidity and more powerful M − O bond, and the introduction of La3+ can improve the ORR activity of the material on this basis. The co-doping of La/Nb elements furtherly stabilizes the lattice structure. Overall, the high ORR activity and CO 2 -tolerance of the cathode manifest a bright application prospect for BLCFN cathode in SOFCs and other membrane reactors. [Display omitted] • A more stable cubic structure is achieved by La/Nb co-doping. • La/Nb co-doping improves the oxygen reduction reaction activity. • BLCFN cathode material exhibits superior resistance towards CO 2 poisoning. • A peak power density of 812 mW cm−2 is achieved at 700 °C with BLCFN cathode. [ABSTRACT FROM AUTHOR]