Electrochemical Reduction of Oxygen and Nitric Oxide at Low Temperature on La[sub 1−x]Sr[sub x]CoO[sub 3−δ] Cathodes

Abstract

Six La1−xSrxCoO3−δ (x=0,0.05,0.15,0.25,0.35,0.50) perovskites were synthesized and characterized by powder X-ray diffraction and cyclic voltammetry on conical electrodes in either air or nitric oxide in argon at 200, 300, and 400°C . At 200°C , the current densities in air was the highest for the strontium-free cobaltite, whereas the current densities were the highest for La0.95Sr0.05CoO3−δ in the nitric oxide-containing atmosphere. This was also the compound with the highest INO/InormalO2 current ratio at 200°C . At higher temperatures, a limiting cathodic current was observed for all of the cobaltites, except for La0.50Sr0.50CoO3−δ , in both air and nitric oxide-containing atmosphere. This was attributed to a rate-limiting chemical step (i.e., dissociation of oxygen or nitric oxide) in the reaction sequence.

Electrochemical Reduction of Oxygen and Nitric oxide at low Temperature on La1-xSrxCr0.97V0.03O3-δCathodes

“…The magnitude of current densities for the LSCrV perovskites can be compared with the magnitude of the current densities obtained for strontium substituted lanthanum cobaltite's (LSCo) under the same conditions as used in this study. 20 The magnitude of the current densities is of the same order of magnitude at 200 and 300 • C. At 400 • C the magnitude of the current densities is similar for low strontium substituted lanthanum cobaltite's, but the magnitude of the current density for the most active LSCo perovskite La 0.5 Sr 0.5 CoO 3-δ are many times higher than for the LSCrV compounds. This is probably due to a high oxide ionic conductivity of the La 0.5 Sr 0.5 CoO 3-δ compound at 400 • C compared to the other compounds.…”

“…For manganite and ferrite based perovskites it has been shown that the properties needed to reduce nitric oxide is due to the amount of a trivalent transition metal ion and the amount of oxygen vacancies, whereas for the cobaltite's the same is probably valid, but with the exception that also the mobility of the oxygen ions is important for the cobaltite's with a high amount of strontium doping. 20,24,25 In the case of the chromites it seems like that the role of the trivalent transition metal cation is less important, and that the electronic conductivity and the amount of oxygen vacancies are the most important properties. The reason for this difference could be that Cr is less catalytic active for the reduction of nitric oxide than the three other transition metal ions.…”

Effect of magnesium on the XPS and Raman spectra of (Ba0.5Sr0.5)(Al0.2-xMgxFe0.8)O3-ξ (x ≤ 0.2)

“…The perovskite-type cubic oxide (ABO 3 ; A = La, Ba, Sr; B = Co, Fe, Al, Mg; O-oxygen) based systems have generated immense interest due to their potential applications as gas separation membranes, solid electrolyte materials, and catalysts besides in fuel cells, sensors, etc [1][2][3][4][5][6][7][8][9][10]. Their membranes possess a unique capacity of oxygen separation from the air and so play a vital role in industry and power generation [10][11][12][13].…”