Synthsis And Applications Of One-dimensional Magnetic Nanomaterials

In recent years,nanocomposites with core-shell and hollow structure have attracted great interest due to their unique structure and properties,which are widely used in catalysis,energy,biology and so on.Carbon nanotube has been researched by Japanese scientists in 1991.Since that,1-D（dimensional）nanostructures such as nanowires,nanotubes,nanobelts and nanorods have attracted great interest.In the past decades,a great deal of 1-D（dimensional）nanomaterials have been synthesized and studied.But it is very hard to control the size,shape and chemical component.In this thesis,we have developed facile methods to synthesis the core-shell and hollow structured functional nanocomposites with good morphology and controllability,which exhibit excellent performance on catalysis and adsorption.Specific contents are as follows:In the first chapter,the trend and characteristics of the functional nanocomposites were smmarized.Meanwhile,the preparation methods of core-shell and hollow nanocomposites were also stated.Finally,the application of functionalized nanocomposites in catalysis and adsorption were described.In the second chapter,the fabrication of hierarchical magnetic magnesium silicate hollow nanotubes were studied.Owing to its unique structure and high surface area the as-prepared hierarchical magnetic hollow nanotubes exhibit excellent adsorption performance on uptake of methylene blue（MB）.Particularly,this strategy can be extended as a general method to prepare other magnetic metal silicate hollow nanotubes.In the third chapter,an extended st?ber method for PDA-Ni²⁺was applied to synthesize Ag NWs@SiO₂@PDA-Ni²⁺.Followed by calcination at 500°C under N₂atmosphere,the Ag NWs@SiO₂@C-Ni with numerous well-dispersed Ni NPs of about 10nm can be easily synthesized.Ag NW s-Ni@C was also synthesized to demonstrate SiO₂was applied to protect Ag nanowires and block the transfer of electron.After that,Tris buffer was applied to replace NH_3·H₂O.The result demonstrated that Ag Cl was existed before calcination.It demonstrated NH_3·H₂O was applied to protect Ag nanowires and block the production of Ag Cl.The catalytic performance of the Ag NWs@SiO₂@C-Ni was evaluated by the catalytic reduction of 4-NP with an excess of Na BH₄.Ag NWs@SiO₂@C-Ni exhibited excellent performance on catalysis.In the forth chapter,an extended st?ber method for PDA-Ni²⁺was applied to synthesize CuxGeOy@Cu/C-Ni.SiO₂was applied to study reduction of PDA in different conditions.SiO₂layer with A thin thickness do not have an effect of protecting Cu Ge O₃nanowires.And copper ions could also be slowly reduced by PDA to product Cu NPs after the carbonization.But when we increased the thickness of SiO₂layer,there was no apparent Cu NPs onto the surface of the product.The catalytic activities of CuxGeOy@Cu/C-Ni and Cu Ge O₃/SiO₂//C-Ni on the reduction of 4-nitrophenol was investigated in this chapter,which suggested that CuxGeOy@Cu/C-Ni has higher catalytic activity than Cu Ge O₃/SiO₂//C-Ni.