Study of oxygen reduction mechanism on Ag modified Sm1.8Ce0.2CuO4 cathode for solid oxide fuel cell

Abstract

Different amount of metal silver particles are infiltrated into porous Sm 1.8 Ce 0.2 CuO 4 (SCC) scaffold to form SCC-Ag composite cathodes. The chemical stability, microstructure evolution and electrochemical performance of the composite cathode are investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), and AC impedance spectroscopy respectively. The composite cathode exhibits enhanced chemical stability. The metal Ag remains un-reacted with SCC and Ce 0.9 Gd 0.1 O 1.95 (CGO) at 800 °C for 72 h. The polarization resistance of the composite cathode decreases with the addition of metal Ag. The optimum cathode SCC-Ag05 exhibits the lowest area specific resistance (ASR, 0.43 Ω cm 2) at 700 °C in air. Investigation shows that metal Ag accelerates the charge transfer process in the composite cathode, and the rate limiting step for electrochemical oxygen reduction reaction (ORR) changes to oxygen dissociation and diffusion process.

Electrochemical Study of the Versatility of a Solid Cell Working both as Fuel Cell and Electrolysis Modes

“…The capacitance C 2 and C 3 are, respectively, of 1.8 10 −4 F cm −2 and 0.5 10 −1 F cm −2 , whereas R 2 and R 3 are of 1.18 Ω cm 2 and 0.62 Ω cm 2 , respectively. If the complete interpretation is difficult , these results, in accordance with results obtained in similar conditions , , , suggest that the corresponding resistances are mainly correlated to gas phase transport across electrode surfaces, such as diffusion and adsorption phenomena , even if a small contribution of charge transfer to R 2 is not excluded. Adding the three resistances R 1 , R 2 , and R 3 (i.e., corresponding to the intersection of the low frequency part of the diagram with the real axis) gives the total resistance R t of the cell, which corresponds also to the slope of the U versus J curve at origin, plotted as the dotted line in Figure .…”

Effects of carbon monoxide, carbon dioxide, and methane on nickel/yttria-stabilized zirconia-based solid oxide fuel cells performance for direct coupling with a gasifier

“…On the contrary the R3/CPE3 loop is unchanged, with comparable R3 and C3 values, suggesting that this loop is associated to a phenomenon which is not dependent on temperature, such as diffusion [31,44e47]. The charge transfer phenomena, which are thermodynamically activated, are even less detectable than at 750 C [40,44,47]. Table 3 also collects the values obtained for the impedance diagram obtained a 780 C, and confirms both the dependence of R1 and (R2A þ R2B) and the independence of R3 and C3 on temperature.…”

Advances in Cathode Materials for Solid Oxide Fuel Cells: Complex Oxides without Alkaline Earth Metal Elements

“…[ 442 ] Some other alkaline earth metal element free oxide materials were also tried with infi ltration method to prepare high-performance oxygen reduction electrodes. [443][444][445][446][447][448] With high electrical conductivity (≈190 S cm −1 ) and compatible TEC (12.2 × 10 −6 K −1 ) but low oxygen ionic conductivity, [ 443 ] the spinel Cu 1.25 Mn 1.75 O 4 phase was impregnated into an YSZ framework to form a new composite cathode, [ 444 ] and an infi ltration amount of 50 wt% was found to exhibit the lowest polarization resistance of 0.3 Ω cm 2 at 750 °C, which was much lower than 8.5 Ω cm 2 from a LSM infi ltrated YSZ cathode.…”