| Carbon-based materials are increasingly popular due to their unique electrical conductivity,structural law,chemical inertness,biocompatibility,mechanical stability and thermal stability.They are widely applied to the sensor field.However,carbon-based material sensors are still lacking in selectivity and sensitivity.Adding metal/metal oxide catalysts can effectively improve the sensitivity and selectivity of the sensor.Noble metals such as Pd and Ag have unique nano-size effects and physicochemical properties,as well as strong electrocatalytic activity,excellent conductivity and biocompatibility,so as to achieve specific identification and sensitive detection of target analytes.It provides a new research scheme for the improvement of sensor performance.The specific research results of this article are as follows:(1)The carbon-coated metal nanoparticles Ag@C core-shell structure nanoparticles were successfully synthesized by hydrothermal synthesis method.Through scanning electron microscope(SEM),transmission electron microscope(TEM),X-ray diffractometer(XRD),Thermogravimetric analyzer(TGA)and other instruments characterize the synthesized Ag@C.The Ag@C core-shell structure nanocomposite was loaded onto the working electrode surface of screen-printed electrodes(SPEs)by drip coating method,and a sensor based on Ag@C material was successfully fabricated.The electrochemical performance of Ag@C material modified SPEs was studied by AC impedance method,cyclic voltammetry and differential pulse voltammetry method.The characterization results show that the synthesized Ag@C is uniformly spherical and has a perfect core-shell structure.The size of the nanoparticles is 330-600 nm,and the Ag NPs are well covered by the carbon material in the center.The experimental results show that,compared with carbon materials,the Ag@C core-shell structure nanocomposite has a good response signal to BPA when the reaction time of hydrothermal synthesis is 4 h,the p H of phosphate buffer solution is 7,the scanning speed is 40m V/s.Due to the excellet electrocatalytic effect,the concentration of BPA in the interval of 1.0×10-7-6.0×10-5mol/L has a linear relationship with the oxidation peak current,and its detection limit is 7.2×10-8 mol/L.(2)The carbon-coated metal oxide nanoparticles,Fe3O4@C core-shell structured nanoparticles were successfully synthesized by hydrothermal synthesis.The synthesized Fe3O4@C was characterized by SEM,TEM,XRD,EDS and other instruments.The Fe3O4@C core-shell nanocomposite material was loaded onto the working electrode surface of SPEs by the drip coating method,and a sensor based on Fe3O4@C material was successfully fabricated.The EIS,CV and DPV were used to study the electrochemical performance of SPEs modified with Fe3O4@C materials.The characterization results show that the Fe3O4@C core-shell structure is uniformly spherical and has a perfect core-shell structure,with a size of about350-500 nm,while the carbon shell is relatively thin.The experimental results show that compared with the traditional carbon-coated metal nanoparticles modified electrode,the Fe3O4@C modified electrode has a excellent electrocatalytic effect on BPA under the conditions of PB buffer solution p H=7 and scanning speed of 50m V/s.It was confirmed by the DPV method that there is a linear relationship between the concentration of BPA and the oxidation peak current in the range of 5.0×10-7-1.3×10-5 mol/L,the detection limit is 5.0×10-8mol/L.(3)The Pd-doped carbon-coated metal nano-particles,namely Pd/Ag@C core-shell structured nano-particle composite materials were successfully synthesized by the impregnation-reduction method.The synthesized Pd/Ag@C was analyzed by SEM,TEM,XRD,EDS and other instruments.The Pd/Ag@C core-shell nanocomposite material was loaded on the surface of the working electrode of SPEs by drip coating method,and a sensor based on Pd/Ag@C material was successfully fabricated.The characterization results show that Pd NPs are uniformly doped on the surface of the Ag@C core-shell structure,showing a uniform spherical shape and having a perfect core-shell structure.The size of Pd/Ag@C nanoparticles is 150-300 nm and Pd NPs is 3-5 nm.The experimental results show that under the condition of p H=7,the Pd/Ag@C modified electrode with appropriate Pd content has a electrocatalytic effect on BPA.Within the range of 8.0×10-8-1.5×10-5 mol/L BPA concentration,the response current increases with the increase of BPA concentration and shows a linear relationship,and the detection limit can reach 1.0×10-8 mol/L.Compared with Pd/C and Ag@C,Pd/Ag@C not only greatly improves the detection sensitivity of bisphenol A,but also greatly reduces the cost of the reactant metal source. |
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