Nano-materials Chemical Sensor Applications,

Nano-materials has great surface area and some special structures, so that it has become a kind of sensor's materials possessing special properties, Nowdays, the study about which has become the focus. It is main character in nano-materials' application of sensors that the amplificatory effect to the signal of the sensor attributing to great surface area of nano-materials. With the nano-materials prepared by our group and others, this paper makes some researchs about chemical sensors that the carbon paste electrodes modified by nano-materials.1 Electrochemical determination of amino acid with carbon paste electrode modified by copper nanoparticlesWith carbon paste electrode modified by copper nanoparticles (average diameter of nanoparticles d≈50nm), direct electrochemical detection of fifteen kind amino acids (including glycine) is firstly achieved in approximately neutral solution(pH=8.0 phosphate buffer solution). The copper nanoparticles can be obtained by reducing CuSO₄ with N₂H₄·H₂O in the ethanol. Then, the carbon paste electrode modified by copper nanoparticles can be used to determine amino acids with Cyclic Voltammetry. About the determination, the linear range of detection(glycine) is 2.5 X10^-5 mol/L⁷.4X 10^-4 mol/L, and the detection of limit (glycine) is 2.5 X 10^-6 mol/L (S/σ>3 ) .2 Direct potentiometric determination of H₂O₂ in waterThere is hydrogen peroxide sensor that don't need to be activated , and which has nice linear range with high sensitivity. The chemical modified carbon paste electrode(CMCPE) is made up of carbon power, manganese dioxide and silicone oil II. In the 0.05 mol/L phosphate solution(20℃), the CMCPE gives that five magnitudes' linear range 1.08X 10^-5 mol/L -0.104 mol/L, with a sensitivity of 63.02 mV/pH₂O₂ and a detection limit of 6.22 X 10^-7mol/L by the direct potentiometry, the CMCPE has fine selectivity, i.e. most anion and cation don't interfere with the detection. Moreover, theCMCPE can be used in pH=7.4 phosphate buffer solution, and has a sensitivity of 31.0 mV/pH₂O₂.3 No standard reagent potentiometric titration of hydrogen peroxideThe carbon paste electrode modified by β-MnO₂ nanorods (CMCPE) is used as the indicator electrode, no standard reagent potentiometric titration of hydrogen peroxide is the first realized. β-MnO₂ nanorods can be prepared very easily with hydrothermal method. With the hydrogen peroxide solution adding and reaching a certain concentration, the potential of the CMCPE would provide a enormous change in pH=3.0 phosphate buffer solution. The end-point of potentiometric titration has relation to the concentration of hydrogen peroxide, According to which, quantitative analysis of the hydrogen peroxide can be achieved. The method is no standard reagent, simple, precise and can be used as a convenient determination of hydrogen peroxide.