| Nanocomposites have the special performance that single nanoparticles can not meet, such as the unique optical, electrical, magnetic, catalytic and other physical and chemical properties, which make them have been widely employed in analytical chemistry and other fields. In this thesis, four types of novel nanocomposites, like TiO2-functionalized graphene nanosheet supported Ag catalyst (Ag-TiO2-graphene), graphene supported silver@Platinum core-shell nanocomposites (Ag@Pt-graphene), gold@platinum core-shell nanoparticles on reduced graphene oxide support (Au@Pt-graphene) and manganese dioxide@silicon dioxide@silver core-shell nanocomposites (MnO22@SiO2@Ag) were prepared by several kinds of control method and synthetic route, and further fabricated in an electrochemical sensor and one supercapacitor based on Au@Pt-graphene/GCE. Investigation on the relationship between these nanocomposites, their sensing interface design and the electrochemical response was carried out, and the new method to detect hydrogen peroxide (H2O2) and nitrite (NO2-) was established.The investigation was beneficial to rich the electrochemical sensing research content and played a certain positive role in extending the application of new types of nanocomposites. In this paper, there has a total of three chapters, the contribution of the author mainly includes the following four aspects.1. TiO2-graphene was prepared by using TiCl3 as the reductant in situ reduction of graphene oxide, and silver nanoparticles was reduced on the surface of functionalized graphene to form the nanocomposite of Ag-TiO2-graphene. The nanocomposite was futher fabricated in electrochemical sensors of hydrogen peroxide (NO2-). The investigation on its electrochemistry and electrocatalysis to NO2- was performed and a new method to detect NO2-. The results revealed that this sensor displayed a good linear relationship between the current response values and the concentration of NO2- with a range from 1.0 μmol·L-1～1.1 m mol·L-1 (r=0.9980), the detection limit was 0.4 μmol·L-1 (S/N=3) and the sensitivity was 112 μA·mM-1·cm-2. In contrast with those H2O2 sensors based on TiO2 or graphene, the electrochemical sensor based on Ag-TiO2-graphene nanocomposite had a lower detection limit and wider detection linear range. Furthermore, this sensor owned a higher anti-inteference ability and a good long-term stability.2. At First, Ag-graphene nanocomposite was prepared by one-step thermal reduction, then Ag nanoparticles were covered with Pt nanoparticles via Galvanic replacement reaction. Ag@Pt-graphene nanocomposite was successfully synthesized and further fabricated in electrochemical sensor of H2O2. Its electrochemistry and electrocatalytic behavior to H2O2 was explored and a new method for determination of H2O2 was established. The results exhibited that this sensor had an excellent electrocatalytic properties to H2O2. The reduction peak current signals had a good linear dependance on H2O2 concentration at the range from 5.0 μmol·L-1 to 12.4 mmol·L-1 (r=0.9989), the determination limit was 0.9 μmol·L-1 ((S/N=3). This preparation method could make silver, platinum and graphene nanomaterial become a unified whole and play a synergistic effect between the nanoparticles effectively, leading to a superior electrocatalytic ability to GO or Ag-graphene nanocomposite.3.The nanocomposite of Au@Pt-graphene was synthesized by one-pot method. An electrochemical sensor based on Au@Pt-graphene nanocoposite and a Au@Pt-graphene/GCE supercapacitor were further fabricated, respectively. Their elctrochemistry, electrocatalysis behavior to H2O2 and the basic capacitance performance of supercapacitor were investigated, and a new method for determination of H2O2 was established. The results showd that the sensor had several advantages, such as a wide linear determination range from 0.5 μmol·L-1 to 22.3 mmol·L-1, a low detection limit of 0.2 μmol·L-1 (S/N=3), good selectivity and stability. The supercapacitor of Au@Pt-graphene/GCE could maintain a good rectangle profile even at the scan rate of 500 mV·s-1 in cyclic voltammetry test and had good symmetrical curves in the process of constant charge/discharge, revealing it showed an excellent electrical double-layer capacitor behavior; Its specific capacitance was 345 F·g-1 under 1 A·g-1 current density, even could reach 300 F·g-1 under 10 A·g-1 current density; After 1000 time constant charge and discharge cycles, the specific capacitance still maintained 96% of the initial value, and the final and the shape of the final five cycles was almostly consistent with the first five; It was obviously that the sensor had the advantage of wider linear range and lower detection limit, while the supercapacitor had excellent coulombic efficiency; Its specific capacitance was 1.5 times of Au-graphene nanocomposite, which was also higher than that reported graphene and active carbon nanomaterial; Furthermore, it had an excellent long-term stability.4.MnO2@SiO2@Ag core-shell nanocomposite was synthesized by layer-by-layer method and further fabricated in H2O2 electrosensor by modified on glassy carbon electrode.Research on its electrochemistry and electrochemical catalytic behavior to H2O2 was performed, and a new method to determinating H2O2 was established. The results revealed that this sensor had better catalytic ability to H2O2 than MnO2, MnO2@SiO2, PVP-Ag, it not only had a wide linear range from 2.0×10-6～8.86×10-3 mol·L-1 (r=0.9990), but also a low detection limit of 7.0×10-10-7mol·L-1(S/N=3)... |
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