Preparation And Performance Study Of Ni Based Magnetic Nanocomposites

In recent years,as an important transition metal,nickel?Ni?has been widely studied not only in catalysis,lithium battery and other fields,but also in the separation of histidine rich proteins.However,the easy agglomeration of these single nickel nanoparticles limits their practical application.Therefore,in order to avoid serious agglomeration,maintain its high activity and good magnetic properties,it is feasible but still challenging to fix it on the appropriate substrate surface to improve its performance.In this paper,the controllable preparation of Ni based magnetic nanocomposites and their protein adsorption and catalytic properties were systematically studied.The specific research contents are as follows:1.A unique nanostructure of Fe₃O₄nanoparticles?NPs?-in/carbon layer/out-Ni NPs was developed and proved to be an efficient catalyst and protein adsorbent.This kind of nanostructure was formed through a space-confined pyrolysis procedure by using polydopamine-Ni²⁺coated Fe-NTA nanowires as the precursor.N-doped carbon interlayer derived from polydopamine?PDA?supported a large amount of Ni NPs and entrapped well-defined Fe₃O₄ NPs,which were obtained through reduction of Ni²⁺,Fe³⁺by carbonized NTA groups and PDA layer.The contributions of unique configuration along with high density of Ni NPs in Fe₃O₄@C-Ni are significant for improving catalysis and protein adsorption performance,which is expected to be a promising alternative to other conventional catalysts and protein adsorbents.Due to the unique novel nanostructure,this nanocomposite possesses wide range of applications,not only for catalytic reactions but also for other inhomogeneous reaction.2.Mn O@Mo O₂@C/Ni was prepared by template method and carbonization method.Firstly,length controlled Mn O₂nanowires were synthesized by hydrothermal method,and then a layer of Ni Mo O₄ nanowires was grown on the surface of Mn O₂ nanowires by chemical vapor deposition.Mn O₂@Ni Mo O₄@PZS was obtained by in-situ polymerization of polyphosphazene.The precursor was calcined at different temperatures to synthesize Mn O@Mo O₂@C/Ni nanomaterials.This process mainly involves the polymerization of polyphosphazene?PZS?and the synthesis of Ni Mo O₄ under alkaline conditions to obtain large surface area structure.Due to the support of lamellar structure,nickel particles are not agglomerated,with large load and uniform distribution,showing high catalytic activity and good recycling performance.In addition,the material has good structural stability,can be repeatedly used in catalysis and has good cycling effect.Moreover,Mn O@Mo O₂@C/Ni can be easily separated by external magnetic field and has good cycle stability,which is very important for practical application.3.Decoration of high coverage of transition metallic Ni nanoparticles?NPs?on magnetic support are of interest for histine-rich protein adsorption.Using a combination of hydrothermal reaction,mussel-inspired coating and carbonization strategy,we have investigated two paths to access hierarchical nickel-based magnetic nanostructures:?1?The Fe₃O₄ spheres are covered with hierarchical Ni Mo O₄ nanosheets and subsequently coated with a layer of polydopamine?PDA?,the Fe₃O₄@Mo O₂?C-Ni composites are synthesized after pyrolysis in nitrogen atmosphere,?2?The Fe₃O₄ spheres are coated with PDA and subsequently covered with hierarchical Ni Mo O₄nanosheets,then the Fe₃O₄@C?Mo O₂-Ni composites are obtained after pyrolysis in nitrogen atmosphere.We find that only route 1,which can be defined as space-confined carbonization strategy,results in the formation of high coverage of nickel NPs with tiny diameter decorated on Fe₃O₄ spheres.Routes 2defined as non-space-confined carbonization strategy lead to the formation of low coverage of Ni NPs with large diameter.Detailed examination of the nickel-based magnetic composites obtained by route 1 displayed superior adsorption capacity for BHb than that of route 2.The results demonstrated that space-confined strategy is greatly beneficial for the synthesis of Ni-based magnetic composites with high coverage,which would pave a novel way for synthesizing high density of Ni-based magnetic composites.