Preparation And Electrochemical Applications Of Graphene/Ag Nanocomposites

Graphene has excellent electrical properties because of its unique electronic band structure is widely applied to energy storage materials. The electrochemical performance of graphene/Ag nanocomposites is increased significantly once again due to the existence of Ag nanoparticles, and this composite can be applied to detect heavy metal ions in water. In this paper, graphene/Ag nanocomposites with different Ag contents were prepared based on expanded graphite and AgNO₃ by a liquid exfoliation method, meanwhile the structure and electrical properties were researched. Then, the glassy carbon electrode was modified by graphene/Ag nanocomposites to detect the heavy metal ions in water. The main contents are generalized as follows:（1） Graphene was prepared by liquid exfoliation method. Then, the morphology and structure of graphene were studied by scanning electron microscope（SEM）, transmission electron microscopy（TEM）, atomic force microscope（AFM）, X-ray diffraction（XRD） and Raman spectroscopy, that proved the graphene was successfully prepared. Furthermore, the conductivity of graphene was 219.09 S/cm, and the capacitance was 18.6 F/g.（2） On the basis of prepared graphene, graphene/Ag nanocomposites were prepared by liquid exfoliation method. The effect of Ag content on the morphology and the structure of graphene/Ag nanocomposite was studied by transmission electron microscopy（TEM）, X-ray diffraction（XRD） and Raman spectroscopy, that proved the Ag nanoparticles were loaded successfully on graphene sheets. The conductivity of the composite material also increased to248.8 S/cm, and the capacitive property of graphene/75%Ag nanocomposites increased to39.01 F/g.（3） The glassy carbon electrode was modified by graphene/Ag nanocomposites, and the modified electrode detected the heavy metal ions of lead, cadmium and mercury in water bysquare wave voltammetry. This study showed that graphene/100%Ag nanocomposites had a good electrochemical response about Pb²⁺ when the pH of PBS buffer solution was 7.0, and the detection limit is 0.5×10-6mol/L. Graphene/100%Ag nanocomposites also had a good electrochemical response about Cd²⁺ when the pH of PBS buffer solution was 7.2, and the detection limit is 5.2×10^-6 mol/L. Graphene had a good electrochemical response about Hg²⁺when the pH of PBS buffer solution was 7.0, and the detection limit is 1.86×10^-6 mol/L. The recovery of three kinds of heavy metal ions detection was between 80% to 120%. So it can be used in the actual detection.