Investigation On Preparation And Characterization Of Graphene-based Nanocomposites And Their Catalytic Application For Ammonium Perchlorate

The thermal decomposition of ammonium perchlorate（AP）can directly affect the combustion behavior of solid propellants.Lower thermal decomposition temperature and more heat release have important applications for AP utilization.Graphene（G）with large specific surface area can inhibit the aggregation of nanoparticles and improve their catalytic performance on the thermal decomposition of AP.G/Ni,G/Fe₂O₃,G/Ni/Fe₂O₃,GO/Fe₂O₃nano-composites and G/Fe₂O₃/AP（ammonium perchlorate）nanostructured energetic materials were prepared using graphene oxide（GO）as the raw material in my thesis.The structure of the nanocomposites was characterized and the catalytic performance of the nanocomposites on the thermal decomposition of AP was investigated.Firstly,G/Ni nanocomposites,G/Fe₂O₃ nanocomposites and G/Ni/Fe₂O₃nanocomposites were prepared by sol-gel method and supercritical carbon dioxide drying technique with NiCl₂·6H₂O and FeCl₃·6H₂O as the precursor.The composition,morphology,specific surface area and pore structure of the three nanocomposites were characterized by X-ray diffraction（XRD）,Raman spectra,X-ray photoelectron spectroscopy（XPS）,scanning electron microscope（SEM）,transmission electron microscope（TEM）and N₂ sorption tests.The catalytic performance of the three nanocomposites on the thermal decomposition of AP was investigated.The results showed that Ni and Fe₂O₃ particles with particle sizes in the nanometer range were well-distributed on the graphene sheets.The three nanocomposites with porous structure showed large specific surface area.The thermal analysis results demonstrated that the G/Ni nanocomposites,G/Fe₂O₃ nanocomposites and G/Ni/Fe₂O₃ nanocomposites can promote the thermal decomposition of AP.When 9%G/Ni nanocomposites,G/Fe₂O₃nanocomposites and G/Ni/Fe₂O₃ nanocomposites were added,the high temperature decomposition temperature of AP decreased from 434.2℃ to 359.6℃,340.8℃,347.9℃and the total heat release increased from 593 J/g to 1631 J/g,1653 J/g,1524 J/g.Secondly,GO/Fe₂O₃ nanocomposites were prepared by electrostatic self-assembly method.The structure of the GO/Fe₂O₃ nanocomposites were characterized and the catalytic performance of the nanocomposites on the thermal decomposition of AP was investigated.The results showed that Zeta potential of Fe₂O₃ nanoparticles with positive electrical charges was 37.2 mV.The Zeta potential of GO with negative electrical charges was-89.9 mV.Electrostatic attraction occurs between opposite charges of Fe₂O₃nanoparticles and GO,thus resulting in the self-assembly process.Dynamic light scattering results showed that the self-assembly process almost completed in about 15 min.XRD、Raman、SEM and TEM showed that Fe₂O₃ nanoparticles were dispersed on the graphene sheets in the GO/Fe₂O₃ nanocomposites.The low temperature decomposition peak was weakened and eventually disappeared.The high temperature decomposition temperature of AP was decreased and the total heat release increased.When 9%GO/Fe₂O₃nanocomposites were added,the decomposition temperature of AP decreased to 347.2℃and the total heat release increased to 1492 J/g.Compared to pure AP,the decomposition temperature decreased by 87.0℃and the total heat release increased by 899 J/g.Finally,G/Fe₂O₃ gels were prepared by sol-gel method with GO as the precursor.Then G/Fe₂O₃/AP nanostructured energetic composites were prepared through solution permeation,solvent and anti-solvent method and supercritical carbon dioxide drying technique.The structure and catalytic performance of G/Fe₂O₃/AP nanostructured energetic composites were characterized and investigated.XPS and XRD analysis showed that G,Fe₂O₃ and AP have been composited.AP with nanometer size was added and dispersed in the porous three-dimensional networks of the G/Fe₂O₃.SEM results demonstrated that G/Fe₂O₃ gels with porous structure were filled by AP in G/Fe₂O₃/AP nanostructured energetic composites.Nitrogen sorption tests showed that specific surface area and total pore volume decreased in comparison with GA and G/Fe₂O₃ gels.Comparing pure AP,the low temperature decomposition peak disappeared,high temperature decomposition temperature of the nanocomposites decreased obviously,while the total heat release significantly increased.The high temperature decomposition temperature decreased by as high as 139.3℃and the total heat release increased to as high as 2383 J/g.