Research On Structure,Morphology,Magentic Properties Of Magnetic Nanofibers And Their Applications For Glucose Sensing

Magnetic nanofibers have been a focus of study due to their unique physical and chemical properties such as outstanding electromagnetic performance,very large specific surface area,continuous length,ultrafine diameter,and are widely used in high-density magnetic recording media,spintronics devices,biomedical and tissue engineering,environmental protection,sensors and other fields.In this thesis,we have fabricated a series of magnetic nanofibers with excellent properties via electrospinning technique,and their morphology,structure,magnetic properties and formation mechnism have been investigated in great detail.Some of our samples have been applied to the removal of Pb²⁺ ions from solutions,non-enzymatic glucose and hydrogen peroxide sensors.The main contents are organized as follows:1.First,we have investigated the morphology,structure,and magnetic properties of the CoFe₂O₄ nanofibers that annealed at different temperatures.In addition,the CoFe₂O₄ nanofibers annealed at 500 ? were applied to the removal of Pb²⁺ ions from aqueous solutions,and to the detection of non-enzymatic glucose and hydrogen peroxide.For investigating the removal of heavy metal ions,adsorption property of our CoFe₂O₄ nanofibers for the Pb²⁺ ions in aqueous solution has been studied.The effects of initial concentration,adsorption time,p H value of the solution on the adsorption property have been studied and it was found that the maximum adsorption capacity for one hour amounts to 23.83 mg/g.For the detection of nonenzymatic glucose and hydrogen peroxide,the CoFe₂O₄ nanofiber decorated nickel foam electrode in alkaline condition was studied by electrochemical cyclic voltammetry and chronoamperometry response measurements.Sensitivity,anti-interference and stability of the modified electrode have been investigated and we found that the sensitivity for the detection of hydrogen peroxide and nonenzymatic glucose amounts to 209.86 u Am M-1cm-2 and 1556.57 u Am M-1cm-2,respectively,which proves the good electrocatalytic activity of our CoFe₂O₄ nanofibers.2.Second,to further improve the properties of the CoFe₂O₄ nanofibers,we have optimized the precursor solution and other parameters of the electrospinning process.Moreover,Co Fe2-xZnxO4 nanotubes have also been fabricated by electrospinning and their morphology,structure and magnetic properties have been investigated.In addition,the CoFe₂O₄ nanotubes have been applied also to the removal of heavy metal ions from aqueous solutions,and to the detection of non-enzymatic glucose and hydrogen peroxide.Our results show that the maximum adsorption capacity for two hour amounts to 62.63 mg/g and the sensitivity of our Co Fe2-xZnxO4 nanotube decorated nickel foam electrode for the detection of hydrogen peroxide and nonenzymatic glucose amounts to 478.9 u Am M-1cm-2 and 1168.56 u Am M-1cm-2,respectively,showing the improved sensitivity of our Co Fe2-xZnxO4 nanbtubes.3.Finally,CoFe_2-xCe_xO₄and NiFe_2-xCe_xO₄ nanoribbons have been fabricated by electrospinning.The composition,morphology,structure,magnetic properties and the formation mechanism of these nanoribbons have been explored.We found that the CoFe₂O₄ nanoribbons annealed at 500 ? show a maximum coercivity of 1348 Oe and the CoFe₂O₄ nanoribbons annealed at 700 ? show a maximum saturation magnetization of 84.41 emu/g.Our results show that the doping of Ce3+ ions can effectively modify the magnetic properties of the CoFe_2-xCe_xO₄and NiFe_2-xCe_xO₄ nanoribbons.