Controlled Synthesis Of Co₃O₄Nanostructures By A Spray Combustion Method And Their Catalytic Properties

In the paper, a novel route for controlled fabrication of nanostructured Co3O4has been proposed based on solution combustion reaction between cobalt nitrate and glycine in the aerosol, which is atomized by supersonic spray equipment and carried into tube stove by flowing air. The effects of concentration of cobalt nitrate, reaction temperature, addition of assistant salts, etc. on the phase and morphology of the products and relevant mechanisms are investigated. The catalytic activities of nanostructured Co3O4with different morphologies on oxidation of CO and thermal decomposition of AP are valued.The results show that uniform330nm Co3O4hollow spheres with23nm constitute crystallites and specific surface area of86.86m2/g can be synthesized via spray combustion method when the0.06M cobalt nitrate reacts with stoichiometic glycine at800℃. The addition of assistant salts into redox aerosol has great significant influence on the morphologies of the products. In the case of NaCl/Co(NO3)2=2,the well-dispersed Co3O4nanoparticles with particle size of65nm can be obtained.The studies on catalytic activities indicate that the morphologies of nano-structured Co3O4have remarkable influence on oxidation of CO. The conversion temperature T100%for CO oxidation is170℃, lowerthan that of the well-dispersed Co3O4nanoparticles by50℃, which reveals that a great improvement in their catalytic activities and dependence on product morphologies. It is demonstrated that nanostructured Co3O4hollow spheres have remarkable influence on thermal decomposition of AP. The addition of2wt.%Co3O4hollow spheres into AP decreases the temperature of AP higher exothermic peak by reduction of110℃and increases the apparent decomposition heat of AP by13fold. It is clear that Co3O4hollow spheres show stronger catalytic property for AP thermal decomposition than micron-sized Co3O4。...