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[Display omitted] • Interface engineering and nano-effects were employed to enhance the ORR activity. • PBSC/CPO heterostructure nanofibers were constructed by in situ self-assembly combined with electrostatic spinning. • PBSC/CPO heterostructure nanofibers facilitate the charge transfer and oxygen ion transport. • PBSC/CPO heterostructure nanofibers exhibits an impressive MPD of 1363 mW cm−2 at 750 °C. The engineering and exploration of cathode materials to achieve superior oxygen reduction catalytic activity and resistance to CO 2 are crucial for enhancing the performance of solid oxide fuel cells (SOFCs). Herein, a novel heterostructure composite nanofiber cathode comprised of PrBa 0.5 Sr 0.5 Co 2 O 5+δ and Ce 0.8 Pr 0.2 O 1.9 (PBSC-CPO-ES) was prepared for the first time through a synergistic approach involving in-situ self-assembly and electrostatic spinning techniques. PBSC-CPO-ES exhibits exceptionally high oxygen reduction catalytic activity and CO 2 resistance, which is attributed to its unique nanofiber microstructure and abundant presence of heterointerfaces, significantly accelerating the charge transfer process, surface exchange and bulk diffusion of oxygen. The introduction of CPO not only effectively reduces the thermal expansion of PBSC but also changes the characteristics of oxygen ion transport anisotropy in layered perovskite materials, forming three-dimensional oxygen ion transport pathways. At 750 °C, the single cell employing the PBSC-CPO-ES heterostructure nanofiber attains an impressive peak power density of 1363 mW cm−2. This represents a notable 60.7 % improvement in comparison to the single-phase PBSC powder. Moreover, PBSC-CPO-ES exhibits excellent CO 2 tolerance and performance recovery after CO 2 exposure. This work provides new perspectives to the design and advancement of future high-performance and high-stability SOFC cathode materials. [ABSTRACT FROM AUTHOR]

The development of cathode materials with high oxygen reduction reaction (ORR) activity is crucial to realize the wide application of solid oxide fuel cells. Nd-doped SrFeO 3-δ (SNF) two-phase nanocomposite was fabricated by a dopant-induced in situ self-assembly process. The SNF nanocomposite comprises 63.4 wt% perovskite main phase (P–SNF) and 36.6 wt% Ruddlesden-Popper second phase (RP-SNF). The average thermal expansion coefficient (TEC) of SrFeO 3-δ is reduced by 36.5 % and down to 13.9 × 10−6 K−1. At 750 °C, SNF demonstrates an impressive output power of 779 mW cm−2, which is twice that of the single-phase SrFeO 3-δ. The superior performance stems from the heterointerface effect of the in situ self-assembled two phases. This effect increases the content of oxygen vacancies, thereby enhancing both chemical oxygen surface exchange coefficient and bulk diffusion coefficient. Moreover, the SNF composite exhibits excellent CO 2 tolerance than the single-phase SrFeO 3-δ. This work presents a promising avenue for exploring multifunctional materials through interface engineering, offering new possibilities for future energy conversion devices. [ABSTRACT FROM AUTHOR]

The development of cathode materials with high oxygen reduction reaction (ORR) activity is crucial to realize the wide application of solid oxide fuel cells. Nd-doped SrFeO 3-δ (SNF) two-phase nanocomposite was fabricated by a dopant-induced in situ self-assembly process. The SNF nanocomposite comprises 63.4 wt% perovskite main phase (P–SNF) and 36.6 wt% Ruddlesden-Popper second phase (RP-SNF). The average thermal expansion coefficient (TEC) of SrFeO 3-δ is reduced by 36.5 % and down to 13.9 × 10−6 K−1. At 750 °C, SNF demonstrates an impressive output power of 779 mW cm−2, which is twice that of the single-phase SrFeO 3-δ. The superior performance stems from the heterointerface effect of the in situ self-assembled two phases. This effect increases the content of oxygen vacancies, thereby enhancing both chemical oxygen surface exchange coefficient and bulk diffusion coefficient. Moreover, the SNF composite exhibits excellent CO 2 tolerance than the single-phase SrFeO 3-δ. This work presents a promising avenue for exploring multifunctional materials through interface engineering, offering new possibilities for future energy conversion devices. [ABSTRACT FROM AUTHOR]

Addressing challenges in oxygen reduction efficiency and CO 2 endurance is essential for advancing the electrochemical energy conversion performance of solid oxide fuel cells (SOFCs). This investigation introduces an innovative strategy by employing Ce doping to enhance the oxygen reduction kinetics and CO 2 resistance of NdBaCoFeO 5+ δ (NBCF) cathodes. Ce doping effectively regulates the oxygen vacancy content, the ratio of Co3+/Co4+ and Fe3+/Fe4+ in NBCF, leading to substantial improvements in oxygen exchange, lattice diffusion, and charge transfer processes. Consequently, a significant enhancement in the oxygen reduction reaction catalytic activity and CO 2 endurance is achieved. At 800 °C, the introduction of 10 mol% Ce doping results in a 65.3% reduction in Rp, reaching 0.024 Ω cm2. Simultaneously, the power density experiences a 50.8% enhancement, reaching 1.0 W cm−2. The current investigation presents a novel avenue towards the advancement of next-generation high-efficiency and stable cathode materials for SOFCs. [ABSTRACT FROM AUTHOR]

The sluggish kinetics of the oxygen reduction reaction (ORR) and susceptibility to CO 2 poisoning present significant challenges in the application of intermediate temperature solid oxide fuel cells (IT-SOFCs). In this study, bismuth (Bi) was introduced as a dopant for the first time to enhance both the ORR activity and CO 2 tolerance of PrBaCoCuO 5+ δ (PBCCO) cathode. Bi doping serves to concurrently modulate the oxygen vacancy content and carrier concentration. This dual regulation enhances the processes of oxygen adsorption, dissociation, and charge transfer, as evidenced by the distribution of relaxation time (DRT) technique. Furthermore, PBBCCO demonstrates exceptional CO 2 tolerance and remarkable performance recovery following exposure to CO 2 -induced degradation. At 800 °C, the polarization resistance (R p) and maximum power density (MPD) of PBBCCO were 0.026 Ω cm2 and 631 mW cm−2, respectively. Notably, R p was reduced by 52.45%, and MPD exhibited an improvement of 45.11% at 800 °C. These findings highlight the significant impact of Bi doping on the performance of the PBCCO double perovskite cathode, underscoring its crucial importance for future developments of novel cathode materials. [ABSTRACT FROM AUTHOR]

Cathodes demonstrating elevated electrochemical catalysis and CO 2 endurance are fundamental for solid oxide fuel cells (SOFCs). Herein, Ta/Cu co-doped SrCo 0.8 Ta 0.1 Cu 0.1 O 3- δ (SCTC) and Nb/Cu co-doped SrCo 0.8 Nb 0.1 Cu 0.1 O 3- δ (SCNC) perovskite oxides were prepared and comparative studied as high-performance SOFC cathodes. Due to the synergistic effects of Ta/Cu and Nb/Cu, the oxygen vacancy content, the ratio of Co3+/Co4+, the average bonding energy and the critical radius in the material are well regulated, resulting in the reduction of TEC and enhanced electrochemical catalytic activity in SCTC and SCNC. At 800 °C, SCTC exhibits an ASR of 0.033 Ω cm2, while it is 0.038 Ω cm2 for SCNC. Additionally, SCTC demonstrates a considerable output performance of 0.89 W cm-2, representing a 15.65% improvement over SCNC. This work offers a highly effective approach to developing materials for next-generation energy transformation devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • Doping combined with surface modification boost the performance of Fe-based cathode. • The R p of PSCFN was reduced by 32.4% through Ni doping. • The R p of PSCFN was further reduced by 56.8% after surface modification. • PrO 2 -PSCFN0.1 achieved an performance of 1190 mW·cm−2 at 800 °C. The development of cathodes with high catalytic activity and stability remains a critical challenge for the commercialization of solid oxide fuel cells (SOFCs). In this study, a novel approach combining doping and surface modification was employed to enhance the catalytic activity and CO 2 resistance of Pr 0.4 Sr 0.6 Co 0.2 Fe 0.8 O 3- δ (PSCF) cathode. Initially, Ni was partially substituted for Fe in PSCF, resulting in the reduction of the average bond energy of metal–oxygen, thereby increasing oxygen vacancy concentration and electrochemical activity. The polarization resistance of PSCFN0.1 at 800 °C was found to be 0.025 Ω·cm2, representing a 32.4 % reduction compared to PSCF. Subsequently, Pr(NO 3) 3 solution was impregnated on the surface of the PSCFN0.1 using a spin-coating technique, resulting in the formation of a PrO 2 /PSCFN0.1 heterostructure that significantly improved the oxygen reduction reaction (ORR) kinetics. At 800 °C, the polarization resistance of PrO 2 -PSCFN0.1 was only 0.016 Ω·cm2, a 56.8 % reduction compared to PSCF. Moreover, the peak power density of PrO 2 -PSCFN0.1 reached 1190 mW·cm−2 at 800 °C, representing a substantial increase of 207.4 % compared to PSCF. Furthermore, PrO 2 -PSCFN0.1-based full cell exhibited excellent performance stability and CO 2 resistance. This work provides an effective strategy to explore novel cathodes for SOFCs. [ABSTRACT FROM AUTHOR]

For intermediate-temperature solid oxide fuel cells (IT-SOFCs), high electrochemical catalytic activity and a suitable thermal expansion coefficient (TEC) are essential criteria. In this investigation, simultaneous Ca and Fe co-doped NdBa 1- x Ca x CoFeO 5+ δ (NBCCF, x = 0, 0.1, and 0.2) double-perovskites were prepared and investigated as SOFC cathode materials. The introduction of Ca and Fe effectively decreased the TECs and improved the oxygen reduction activity of the cathode. The average TEC of NdBa 0.9 Ca 0.1 CoFeO 5+δ (NBCCF1) at 30–850 °C was 19.1 × 10−6 K−1, which is decreased by 27.1 % compared to the only Fe-doped NdBaCoFeO 5+δ (NBCF). According to the distribution of relaxation time (DRT) analysis, the rate-limiting steps of the oxygen reduction reaction (ORR) include bulk diffusion and surface exchange of oxygen, and Ca doping can improve both steps. The maximum power density of the single cell with NBCCF1 as cathode reached 665 mW cm−2 at 750 °C. The polarization resistance decreased from 0.0722 to 0.0482 Ω cm2 at 800 °C. These findings indicate NBCCF1 is a viable cathode candidate for IT-SOFC. [Display omitted] • Ca and Fe co-doped NdBaCo 2 O 5+δ double perovskites were synthesized. • Ca and Fe co-doping effectively decreased the TECs of the cathode. • Ca and Fe co-doping significantly increaseed the oxygen vacancy concentration. • NBCCF1 cathode has an output power density of 665 mW cm−2 at 750 °C. [ABSTRACT FROM AUTHOR]