Abstract: The La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ(LSCF) composite oxide was prepared via combined EDTA-citrate complexing process with concentrated nitric acid treatment. The treatment would result in the self-combustion of solid state precursors at low temperatures. The effect of preparing conditions on LSCF’s catalytic properties was investigated by using decomposition of peroxide hydrogen as the model. The FT-IR results of the solid state precursor and the pH values of aqueous solution of it were studied to determine the mechanism of the thermal decomposition of organic in the precursor and of the self-combustion process. Moreover, XRD was employed to characterize the crystal structure of LSCF calcined at higher temperatures. The study shows that the treatment can depress the growth of crystallite and improve the
catalysis for decomposition of peroxide hydrogen. Of the all samples, the LSCF-40-900 has the highest activity to the decomposition of peroxide hydrogen.

Key words: perovskite-type oxide, La0.6Sr0.4Co0.2Fe0.8O3-δ, HNO3 treatment, decomposition of peroxide hydrogen