Study On Preparation, Electrochemical Character And Application Of Nanoparticles Modified Electrode

Due to the unique character of nanoparticles such as optical, electrical and catalytic character, nanoparticles have attracted much attention of many chemists for their novel application in modified electrode. In this paper, nanoparticles modified electrode has been fabricated by combining nanotechnique with electrochemical method. Besides, nanoparticles modified electrode fabricated by us is taken into the study on bio-molecular, neurotransmitter and environmental pollution. First, the silver nanoparticles modified electrodes made by adsorption or covalence self-assembly have been fabricated. The electrochemical behaviors of SCN^-and hydroquinone on the modified electrode have been studied with cycle voltammetry, different pulse voltammetry and electrochemical impedance spectroscopy. It showed that SCN^-can be quantitatively determined with adsorption silver nanopaticles modified electrode and the detection limit is 4.137×10^-8 mol/L. The content of SCN^-in saliva can be determined by this method and the result is satisfied with us. The response of hydroquinone on the covalence self-assembly silver nanoparticles modified electrode is also good. The peak current of hydroquinone is linear with its concentration on this modified electrode and the detection limit is 1.720 ×10^-7 mol/L. The application in determination of hydroquinone in imitative waste water sample is satisfied. Secondly, the preparation and application of gold nanoparticles (GNP) modified electrode has been discussed: GNP are modified onto the 1,4-benzenedimethanethiol (BDT) modified gold electrode with covalence bond and then this modified electrode (GNP/BDT/Au) was immersed in Hb from its solution at pH6.2 to form a Hb/GNP/BDT/Au electrode. When the Hb/GNP/BDT/Au electrode was put into blank phosphate buffer solution, a pair of well-defined CV peaks were observed at about -0.180V(vs.SCE) characteristic of Heme Fe(III) / Fe(II). The Hb/ GNP/BDT/Au electrode can catalyze the electroreduction of H₂O₂ and O₂ with a significant lowering of overpotential. Thus based on Hb immobilized GNP modified electrode, a novel reagentless H₂O₂ or O₂ biosensor will be constructed. Thirdly, fabrication of Fe₃O₄ nanoparticles modified electrode and its application in electrocatalyzing dopamine (DA) are studied. Fe₃O₄ nanoparticles modified electrode is fabricated by adsorption. The electrochemical behavior of DA on this modified electrode is investigated and the result shows that the oxidation peak current of DA increases obviously. The result shows that it also can eliminate the interference of AA and then DA can be determined selectively. It is applied in the sample determination and the result is satisfied with us. Besides, the catalytic mechanism is discussed primarily. Last, catalyze of active silver particulate on the kinetic electrochemical benavior of formaldehyde is investigated. The reduction peak of formaldehyde on silver micro-disk can be found at 0.00V in the presence of a little I^-or Br^-. Discussion of mechanism shows that Ag⁺ produced during the anodization combines with I^-or Br^-to form insoluble salt AgI or AgBr, and then it is reduced to active silver during a cathodic stripping potential sweep. The active silver can catalyze the dimethanol dehydrating on the electrode surface and the reduction peak of formaldehyde is observed in the negative sweep. It is hopeful to establish a direct, fast and sensitive method to detect the concentration of formaldehyde.