Construction And Application Of Electrochemical Sensors Based On Nanocomposites

In recent years,various nanomaterials have been favored in the electrochemical field due to their unique structure and excellent electrochemical properties.Nanometal materials,especially nanometal sulfides,PtNPs as well as AuNPs are widely used in electrochemical sensors because of their simple synthesis and good electrocatalytic performance.Functionalized graphene overcomes the defects of graphene and enables the two-dimensional layered structure of graphene to be taken full advantage.Electrodes modified by a kind nanomaterial often fail to achieve an ideal electrocatalytic effect.If two or more kinds are combined,it is often possible to make up for each other and to play a synergistic role to construct an electrochemical sensor with excellent performance.For this,the thesis focuses on the researches on the composite materials of nanometal materials including functionalized graphene,as shown below:1.Nanocomposites of CoS₂ and ionic liquid functionalized graphene?IL-GR?were prepared.The morphology and composition of the composites were characterized to confirm that the composites have excellent structure and good dispersion.The as-prepared nanocomposites were subsequently used to build serving as a hydrazine?N₂H₄?electrochemical sensor.The electro-catalytic activity of the prepared sensor towards the N₂H₄ oxidation reaction was estimated by cyclic voltammetry?CV?and amperometric methods.A linear dependence was found between the oxidation peak current and the concentration of N₂H₄.Thus,linear calibration plots were obtained over wide linear ranges of 5¹00?M and 100⁴00?M,with a relatively low detection limit of 0.39?M?S/N=3?.The prepared sensor exhibited good electrocatalytic performance towards the detection of N₂H₄.The sensor was successfully used for the practical determination of N₂H₄ in lake water samples with satisfactory recoveries.2.A highly sensitive enzyme-free glucose sensor was constructed by Ni₃S₂nanomaterials compounded with IL-GR.The structure of Ni₃S₂/IL-GR nanocomposites was characterized by SEM,TEM,XRD and XPS.The electrochemical properties of this enhanced material toward glucose detection were studied by CV and amperometric methods.Compared with the bare GCE and the IL-GR/GCE,the Ni₃S₂/IL-GR/GCE showed significant electrocatalytic activity for glucose oxidation.A wide linear range of0⁵00?M was obtained with a detection limit of 0.161?M?S/N=3?.Some interferences have been considered in the detection of glucose on Ni₃S₂/IL-GR/GCE.The results showed that there was no significant change in the current response of glucose indicating its strong anti-interference ability.Further,the sensor was successfully applied to the detection of glucose in fetal bovine serum.3.The MoS₂ nanomaterials were synthesized by hydrothermal synthesis and combined with Au nanoparticles and IL-GR to construct a novel electrochemical sensor for bisphenol A.By controlling the reaction conditions,nanoflower-like MoS₂ was prepared.The electrochemical sensor based on AuNPs/MoS₂/IL-GR has good electrochemical response to bisphenol A,excellent electrocatalytic performance,and can realize the detection of bisphenol A in different water samples under optimized experimental conditions.4.The Ketchen Black?KB?with good conductivity and metal organic frameworks?MOFs?with excellent biological compatibility and load capacity are used to carry the PtNPs to construct an electrochemical sensor with good electrochemical response,and applied to the detection of the ofloxacin.The structure and composition of PtNPs/KB/MOFs nanocomposites were characterized by TEM and SEM.The detection of ofloxacin by CV method shows that the electrochemical sensor has high sensitivity,low detection limit,good stability and reproducibility.In addition,in the range of 0.08¹00?M,the current responses had a good linear relationship with the concentration of ofloxacin,and the detection limit was 0.037?M?S/N=3?.Finally,the prepared electrochemical sensor was successfully used to detect ofloxacin in serum.