Decreasing the Polarization Resistance of (La,Sr)CrO_3−δ Solid Oxide Fuel Cell Anodes by Combined Fe and Ru Substitution

Abstract

The perovskite compounds La 0.33 Sr 0.67 Cr 1−x−yFe x Ru y O 3−δ (LSCrFeRu, x = 0.62, 0.57, and 0.47; y = 0.05, 0.14, and 0.2, respectively) were synthesized and assessed as a new type of solid oxide fuel cell (SOFC) anode in composite with Gd 0.1 Ce 0.9 O 2-β (GDC) in La 0.9 Sr 0.1 Ga 0.8 Mg 0.2 O 3-ε / La 0.4 Ce 0.6 O 2 bilayer electrolyte-supported cells. By comparing anode polarization resistance R P,A values for the LSCrFeRu compounds to the either exclusively Fe-or Ru-substituted (La,Sr)CrO 3−δ perovskites, the present results demonstrate that the two substituent cations work synergistically to provide further reduction in R P,A from 0.290 Ω·cm 2 for La 0.33 Sr 0.67 Cr 0.33 -F e 0 . 6 7 O 3 − δ ( L S C r F e ) a n d 0 . 2 3 5 Ω · c m 2 f o r La 0.8 Sr 0.2 Cr 0.8 Ru 0.2 O 3−δ (LSCrRu) to 0.195 Ω·cm 2 for LSCrFeRu (all measured in humidified hydrogen at 800°C). These impedance results also strongly suggest that hydrogen dissociative adsorption was the rate-limiting step in the hydrogen oxidation reaction sequence for LSCrFe anodes at some of the pH 2 and temperatures measured. However, the formation of Ru nanoparticles on LSCrFeRu and LSCrRu surfaces, observed by scanning and transmission electron microscopy, appears to promote hydrogen dissociation. Substituting even small amounts of Ru into (La,Sr)(Cr,Fe)O 3−δ perovskites is thus sufficient to make hydrogen electrochemical oxidation the rate-limiting step, resulting in anodes with significantly reduced R P,A .

Fast Response, Highly Sensitive and Selective Mixed-Potential H2 Sensor Based on (La, Sr)(Cr, Fe)O3-δ Perovskite Sensing Electrode

“…The power law-type dependence, Ri  CH2 n , was obtained with n= -0.45, -0.31, and -0.16 at 450 ˚C, 500 ˚C, and 550 ˚C, respectively. Similar power law dependence of anodic polarization resistance on the H2 partial pressure has been observed in several studies on solid oxide fuel cells 14,24. According to the model Zhu et al developed, a power law exponent of -1 corresponded to dissociative adsorption of H2 as the rate-limiting…”

A robust and active hybrid catalyst for facile oxygen reduction in solid oxide fuel cells

“…S1) under the conditions of our study (solution infiltration of catalysts into a porous LSCF cathode). The advantages of the nanoparticles derived from an exsolution process over those from other deposition techniques (such as solution infiltration of nanoparticles 27,28 ) include better control over particle size, distribution, and morphological stability. To probe the surface chemistry and electronic structure of the hybrid catalyst in order to explain the mechanism of performance enhancement, we deposited a thinfilm of the catalyst on a model cell with a flat, dense LSCF electrode using pulsed laser deposition (PLD) (ESI, † Fig.…”

The Electrochemical Properties of Sr(Ti,Fe)O3-δfor Anodes in Solid Oxide Fuel Cells

“…34 This Fe0 formation was accompanied by strongly increased electrochemical water splitting kinetics. Improvement of the hydrogen electrode performance by exsolution of easily reducible transition metals was also demonstrated on various (La,Sr)TiO 3 based materials, 9,55,56 (La,Sr)FeO 3-δ , 33 (La,Sr)CrO 3-δ based materials, [57][58][59][60] and rare earth vanadates. 61 Decreased anode polarization resistance in cells with (La,Sr)(Cr,Ru)O 3-δ anodes was quantitatively modelled by enhanced hydrogen dissociative adsorption at exsolved Ru nanoparticles.…”