Fabrication Of Iron Oxide Nano-material Modiifed Electrodc And Its Application For Determination Of Heavy Metal Ions

Nano-materials have been found broad utility in electrochemical sensors. In thispaper, we fabricated several kinds of iron oxide nano-materials such as Fe₂O₃andFe₃O₄and then modified them with other materials on the electrode to form differentsensors. Further more, we explored the capability and application of the sensors. Thedetails are summarized as follows:（1） In this chapter, we reviewed the development of sensors and the mostrelevant applications in environmental analysis. And then the thesis idea waspresented.（2） Shuttle-like Fe₂O₃nanoparticles （NPs） were prepared by microwave-assistedsynthesis and characterized by scanning electron microscopy and X-ray diffraction.The NPs were immobilized on a glassy carbon electrode and then covered withdsDNA. The resulting electrode gives a pair of well-defined redox peaks for Pb（II） atpH6.0, with anodic and cathodic peak potentials occurring at0.50V and0.75V（vs.Ag/AgCl）, respectively. The amperometric response to Pb（II） is linear in the rangefrom0.12to40nM, and the detection limit is0.1nM at a signal-to-noise ratio of3.The sensor exhibits high selectivity and reproducibility, and was successfully appliedto determine Pb2+in water samples.（3） In the chapter3, Spherical Fe3O4nanoparticles （NPs） were prepared byhydrothermal synthesis and characterized by scanning electron microscopy and X-raydiffraction. A glassy carbon electrode was modified with such NPs to result in asensor for Pb （II） that is based on the strong inducing adsorption ability of iodide. Theelectrode gives a pair of well-defined redox peaks for Pb（II） in pH5.0buffercontaining10mM concentrations of potassium iodide, with anodic and cathodic peakpotentials at-487mV and-622mV （vs. Ag/AgCl）, respectively. The amperometricresponse to Pb （II） is linear in the range from0.10to44nM, and the detection limit is40pM at an SNR of3. The sensor exhibits high selectivity and reproducibility, andhas been used for quantitative detecting Pb2+in real samples.（4） In the chapter4, dendritic-like Fe₂O₃nanoparticles （NPs） were prepared by hydrothermal synthesis and characterized by scanning electron microscopy and X-raydiffraction. An electrochemical sensor for Hg（II） was fabricated based on the glasscarbon electrode modified with multi-walled carbon nanotubes-wired Fe₂O₃film.The resulting electrode gives a pair of well-defined redox peaks for Hg（II） at pH5.0,with anodic and cathodic peak potentials occurring at0.28V and0.16V （vs.Ag/AgCl）, respectively. The amperometric response to Hg（II） is linear in the rangefrom0.18to50M, and the detection limit is0.07nM at a signal-to-noise ratio of3.The sensor exhibits high selectivity and reproducibility, was successfully applied todetermine Hg2+in water samples.