Synthesis Of Carbon Nanotubes Or Nitrogen-doped Carbon Nanostructure-supported Metal And Metal Oxide Composites And Their Applications In Electrochemical Sensing

In recent years,the development of metals and their oxides/carbon nanocomposites has been widely concerned in the field of electrochemical sensors.Combining metals and their oxides with carbon nanomaterials can present better biocompatibility and more catalytic active sites.In this thesis,the carbon nanotubes or nitrogen-doped carbon nanomaterials were used as the support matrix for the deposition of metal or bi-metallic oxide nanoparticles,and then the obtained composites were employed to fabricate the non-enzymatic electrochemical sensors.Through the optimization of experimental conditions and various physical and electrochemical techniques,the electrocatalytic properties of as-fabricated sensors for glucose or hydrogen peroxide detection are thoroughly investigated.The original results obtained are as follows:(1)Nitrogen doped carbon nano-networks(NCNWs)were prepared via a solvothermal route using choline chloride/urea deep eutectic solvents(DES)as the medium and glucose as the carbon source.Then,a novel Pd/NCNWs composite was obtained by depositing Pd nanoparticles(PdNPs)on the NCNWs.The morphology,surface valence state and structure of the synthesized materials were analyzed by scanning electron microscopy(SEM),transmission electron microscopy(TEM),X-ray powder diffraction(XRD)and X-ray photoelectron spectroscopy(XPS).At the same time,the electrochemical efficiency and sensing properties of the synthesized materials were studied by cyclic voltammetry(CV)and current-time(i-t)methods.The results show that the designed Pd/NCNWs/GCE sensor presents good sensing features towards target analyte in terms of wide linear range(0.0285⁴.99 mM),lower limit of detection(2.27?M,S/N=3),high sensitivity(83.34?A mM^-1 cm^-2),and excellent reproducibility(relative standard deviation of 4.3%),stability(the oxidation peak current of the sensor still maintains 84.3%of the initial value after 500 CV cycles)and anti-interference ability.(2)The NiCeO_x/MWCNTs nanocomposite was synthesized by hydrogen reduction method using carbon nanotubes as the carrier matrix,and then this material was employed to develop a non-enzymatic sensing platform for efficient and rapid detection of glucose.The synthesized nanocomposites were characterized through SEM,TEM,XRD and XPS.The electrochemical performance of the sensor was systematically studied by CV and i-t methods.Under the optimized conditions,the sensor shows a good linear relationship between glucose concentrations ranging from0.03211 to 2.12 mM.In addition,the sensor exhibits low detection limit(9.5?M,S/N=3),high sensitivity(315.63?A mM^-1 cm^-2)and excellent reproducibility(relative standard deviation of 4.6%),stability(the oxidation peak current of the sensor retains97.7%of the initial value after 500 continuous cycles,the response current is 81%of the initial value after one week)and anti-interference ability and showed good selectivity in the determination of human serum samples(recoveries were 100.8%,101.4%and 99.6%,respectively).(3)The nitrogen doped carbon nano-sheets(NCNs)were prepared via a solvothermal method using choline chloride/urea DES as the medium and citric acid as the carbon source.Then,the CuMnO_x nanoparticles were supported on the surface of NCNs and a non-enzymatic H₂O₂ sensor was fabricated based on this CuMnO_x/NCNs composite.The as-synthesized nanocomposites were physically characterized by TEM,XRD and XPS.Under the optimized conditions,the electrochemical performance of the sensor was tested by CV and i-t methods.The results show that the prepared enzyme-free H₂O₂ sensor has a wide linear range(0.078⁵.63 mM),high sensitivity(165?A mM^-1 cm^-2),low detection limit(15.6?M)and excellent reproducibility(relative standard deviation of 3.6%),stability(the reduction peak current retains 80.3%of the initial value after 500 continuous cycles)and anti-interference ability.