Study On Enzyme-free Electrochemical Sensor Based On Nickel Composites

Nickel and nickel oxide have stable chemical properties,excellent biocompatibility and good electrocatalytic performance,is widely used in enzyme-free electrocheical sensors.However,there is a certain defect in nickel and its oxides,which leads to some restrictions on the application of enzyme-free electrochemical sensors.In this paper,nickel-based composites were prepared by doping nickel and its oxides with other materials to improve the electrocatalytic activity of Ni-based composites and construct novel enzyme-free sensors.The main contents of this thesis are follows:（1）Preparation of carbon-nitrogen doped nickel oxide microspheres（Ni O）novel composites（C-N/Ni O）and fabricate hydrogen peroxide（H₂O₂）enzyme-free electrochemical sensors.Ni O was prepared by solvothermal method,and C-N/Ni O composites were obtained by calcining the mixture of Ni O and diblock copolymer poly（2-hydroxyethyl methacrylate）-b-poly（2-（dimethylamino）ethyl methacrylate）(PHEMA₂₀₀-b-PDMAEMA₁₀₀)at high temperature.The morphology and electrocatalytic performance of the samples as prepared were characterized by scanning electron microscopy（SEM）,X-ray diffraction（XRD）,cyclic voltammetry（CV）and amperometrc current-time curve（i-t）.The result shows that the C-N/Ni O modified glass carbon electrodes（GCE）（denoted as C-N/Ni O/GCE）exhibits excellent electrocatalytic performance for hydrogen peroxide（H₂O₂）determination:alower detection limit with 0.042μM（S/N=3）.Therefore,the Ni O@C/N/GCE has potential to be excellent for fast determination of hydrogen peroxide,which is applied to medicine management,environmental protection and food safety.（2）Preparation of Ag coated Ni O hollow spheres composites（Ag/Ni O HS）and fabricate glucose enzyme-free electrochemical sensors.Ni O HS was synthesized by hydrothermal method,and then Ag/Ni O HS was fabricate by seed-induced growth procedure.The morphology and electrocatalytic performance of the samples as prepared were characterized by SEM,XRD,and CV.The result shows that the 2%Ag/Ni O HS modified GCE（denoted as 2%Ag/Ni O HS/GCE）exhibits excellent electrocatalytic performance for glucose determination:a much higher sensitivity withrange under the synergistic effect was achieved between Ag and Overall,these results indicate that the Ag Ni O HS based sensor is a promising candidate in the development of highly sensitive and selective nonenzymatic glucose sensors.（3）Preparation of nickel doped graphitic carbon nitride（Ni/g-C₃N₄）composites and fabricate bisphenol A（BPA）enzyme-free electrochemical sensors.Ni/g-C₃N₄ was prepared by thermal treatment the mixture of melamine and Ni Cl₂·6H₂O.The morphology and electrocatalytic performance of the samples as prepared were characterized by SEM,XRD,infrared（IR）,alternating-current impedance（EIS）and differential pulse voltammetry（DPV）.The result shows that the 10%Ni/g-C₃N₄modified GCE（denoted as 10%Ni/g-C₃N₄/GCE）exhibits excellent electrocatalytic performance for BPA determination:the linear range are 0.01 n M to 1μM and 1μM to 100μM,with a limited detection of 4.34 n M（3S/N）.Therefore,Ni/g-C₃N₄composites based sensor has great potential value in BPA detection.