Neodymium Calcium Manganese Perovskite-type Oxide Preparation And Oxygen Reduction Catalytic Properties

The high catalytic and inexpensive catalyst applying to oxygen electrode is the key problem on alkaline fuel cells.The inexpensive perovskite-type oxide Nd_0.6Ca_0.4MnO₃ was prepared by sol-gel-Conventional heating and Microwave heating in this thesis;XRD, SEM,TEM were employed to characterize the prepared catalysts.The polarization curve technique,electrochemical impedence spectroscopy (EIS) methods and the chronoamperometry(CA) were used to study the electrocatalytic performances of the prepared oxides for Oxygen Reduction Reaction(ORR) in alkaline medium.When the catalyst was prepared by sol-gel-Conventional heating,the premonitory solid gelatin was made,then fired to steady complicated oxide.The oxide behaves high catalytic performance,giving a density of -82 mA·cm^-2 at the potential -0.2V(vs Hg/HgO) under air atmosphere and -141 mA·cm^-2 under oxygen atmosphere at room temperature, respectively;A series of factors were considered during preparing process.The oxide Nd_0.6Ca_0.4MnO₃ was also prepared by Microwave heating, The prepared catalyst was a kind of well-proportioned and slight diameter grain,can get to 15-20nm.The oxide behaves high catalytic activity, giving a density of-80mA·cm^-2 at the potential -0.2 V(vs Hg/HgO) under air atmosphere.The Zinc/air fuel cell was fabricated,the prepared oxide as the catalyst of air diffusion electrode,and the discharge performance of the fuel cell was research.The carbon material is applied as the gas diffusion electrode carrier, also supplied active side for catalyst,can complex affect the catalytic activity of catalyst.During process of catalyzing,O₂ adsorbed on carbon materials surface first.The oxygen adsorption on the surface of graphite was studied,this study is very important to understanding the ORR catalytic mechanism.So,this adsorption process is studied by DFT(density functional theory) methods and module Dmol3 of Materials Studio software.