Cobalt-Free Double Perovskite Oxide as a Promising Cathode for Solid Oxide Fuel Cells

Abstract

Double perovskite oxide PrBaFe 2 O 5+δ is a potential cathode material for intermediate-temperature solid oxide fuel cells. To improve its electrochemical performance, the trivalent element Ga is investigated to partially replace Fe, forming PrBaFe 2−x Ga x O 5+δ (PBFGx, x = 0.05, 0.1, and 0.15). The doping effects on physicochemical properties and electrochemical properties are analyzed regarding the phase structures, element valence states, amount of oxygen vacancies, content of oxygen species, oxygen surface exchange coefficients (k chem ), electrochemical polarization resistance, and single-cell performance. Specifically, PBFG0.1 exhibits improved k chem, such as a 19% improvement from 4.09 × 10 −4 to 4.86 × 10 −4 cm s −1 at 750 °C, due to the increased concentration of reactive oxygen species and oxygen vacancies. Consequently, the interfacial polarization resistance is decreased by 28% from 0.057 to 0.041 Ω cm 2 at 800 °C. The subreaction steps of the oxygen reduction reaction in the PBFG0.1 cathode are further investigated, which suggests that the oxygen dissociation process is greatly enhanced by doping Ga. Meanwhile, doping Ga increases the peak power density of the anode-supported single cell by 36% from 629 to 856 mW cm −2 at 800 °C. The single cell with the PBFG0.1 cathode also exhibits good stability in 100 h of long-term operation at 750 °C.

Utilizing High Entropy Effects for Developing Chromium‐Tolerance Cobalt‐Free Cathode for Solid Oxide Fuel Cells

“…Additionally, the detailed PPDs of the PBF and LPNSGBF shown in Figure 6d, exhibit excellent electrochemical performance when compared with most of the reported LnBaFe 2 O 5+ δ ‐based cathodes, such as Sm 0.8 La 0.2 BaFe 2 O 5+ δ , [ 31 ] PrBaFe 2/3 Co 2/3 Cu 2/3 O 5+ δ , [ 32 ] Pr 0.9 Ca 0.1 BaCoFeO 5+ δ , [ 33 ] PrBaFe 1.9 Ga 0.1 O 5+ δ , [ 34 ] GdBaFeNiO 5+ δ , [ 35 ] GdBaFe 2 O 5+ δ , [ 35 ] LaBaFe 1.85 Sn 0.15 O 6‐ δ , [ 36 ] and PrBaFe 2 O 5+ δ . [ 34 ] As shown in Figure 6e, the EIS data reveal that the enhanced electrode activity results from the decreased value of R p (from 0.46 to 0.28 Ω cm 2 ), based on the close (0.19 Ω cm 2 for PBF and 0.18 Ω cm 2 for LPNSGBF) ohmic resistance ( R o ) at 800 °C. The corresponding DRT curves can be divided into three peaks P1, P2, and P3.…”

“…By comparing, as shown in Figure 6c, the PPD of single‐cell with LPNSGBF is higher than that of PBF (794.96 mW cm −2 ) at 800 °C, which demonstrates the electrochemical performance can be dramatically enhanced by high entropy doping. Additionally, the detailed PPDs of the PBF and LPNSGBF shown in Figure 6d, exhibit excellent electrochemical performance when compared with most of the reported LnBaFe 2 O 5+ δ ‐based cathodes, such as Sm 0.8 La 0.2 BaFe 2 O 5+ δ , [ 31 ] PrBaFe 2/3 Co 2/3 Cu 2/3 O 5+ δ , [ 32 ] Pr 0.9 Ca 0.1 BaCoFeO 5+ δ , [ 33 ] PrBaFe 1.9 Ga 0.1 O 5+ δ , [ 34 ] GdBaFeNiO 5+ δ , [ 35 ] GdBaFe 2 O 5+ δ , [ 35 ] LaBaFe 1.85 Sn 0.15 O 6‐ δ , [ 36 ] and PrBaFe 2 O 5+ δ . [ 34 ] As shown in Figure 6e, the EIS data reveal that the enhanced electrode activity results from the decreased value of R p (from 0.46 to 0.28 Ω cm 2 ), based on the close (0.19 Ω cm 2 for PBF and 0.18 Ω cm 2 for LPNSGBF) ohmic resistance ( R o ) at 800 °C.…”

Unraveling the promotional role of BaCO3 in the electrode reaction kinetics of an SmBaFe2O5+δ air electrode of reversible solid oxide cells

“…17 Therefore, modication strategies like lattice doping are employed to tailor the oxygen vacancy concentration and enhance the catalytic activity. [17][18][19][20] For instance, substituting Fe with weak metal-oxygen bond elements Zn or Ga can increase the oxygen vacancy concentration, and enhance the oxygen transport kinetics, resulting in a decreased R p value. 19,20 In addition to lattice doping strategies, inltration is an efficacious approach to boost the electrode reaction kinetics.…”

“…[17][18][19][20] For instance, substituting Fe with weak metal-oxygen bond elements Zn or Ga can increase the oxygen vacancy concentration, and enhance the oxygen transport kinetics, resulting in a decreased R p value. 19,20 In addition to lattice doping strategies, inltration is an efficacious approach to boost the electrode reaction kinetics. Many of the frequently studied oxygen ion conductors and mixed electronic and oxygen ionic conductors have been used to decorate the electrode, like Sm 0.2 Ce 0.8 O 2−d into La 0.6 Sr 0.4 MnO 3 , 21 Gd 0.1 Ce 0.9 O 2−d (GDC) into NdBa 0.9 Co 2 O 5+d , 22 and La 1−x Sr x CoO 3−d into La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3−d -GDC (LSCF-GDC).…”

Highly stable lanthanide cluster-based luminescent materials constructed from β-diketone to 1,10-phenanthroline exhibiting ultrahigh photoluminescence and efficient pesticide detection

“…36 Luminescent lanthanide complexes have been extensively studied in luminescence recognition and detection, including cation and anion recognition, solvate detection and temperature sensing. [37][38][39][40] Consequently, luminescent lanthanide complexes are ideal candidates as fluorescent probes to enhance the sensitivity and selectivity of pesticide detection.…”