Preparation of Nanometer La1-x SrxMnO3 and Application in Air-Cathode

The nanometer La1-xSrxMnO3 perovskite catalyst was prepared by sol-gel method. The optimum conditions of material preparation were gained by studying the effect of process parameters, such as pH value, temperature of water bath, drying method of gel and the sintering mode of sol, on the crystal structure of the nanometer La1-xSrxMnO3. The average diameter of the La1-xSrxMnO3 catalysts is 20 ∼ 50 nm. The softly congregated nanometer La1-xSrxMnO3 could be separated by ultrasonic and loaded on active carbon uniformly, thus the properties of air cathode was improved significantly. The influence of doping Sr on the catalytic performance was studied by measuring the steady-state polarization curve of the air cathode. It was found that doping Sr would induce the deformation of La1-xSrxMnO3 lattice, and the main factors affecting the catalyst's performance were concentration of oxygen vacancies in the crystal, the ratio of Mn4+/Mn3+ and the variation of La1-xSrxMnO3 paramagnetism. The result showed that the catalytic performance of La1-xSrxMnO3 increased with the amount of doping Sr initially, and the performance was the best at x =0.4, then decreased. The current density reached 324 mA · cm−2 at -200 mV vs Hg/HgO while electrolyte was alkaline solution at room temperature.