Preparation and capacitance performance of Ag-graphene based nanocomposite

摘要

Ag-graphene nanocomposite has been prepared by a simple way in situ simultaneous reduction of Ag~+ ions and graphite oxide in a solution of hydrazine hydrate at 95 ℃ for 12 h. The morphology and structure of the obtained material are examined by XRD, SEM, TEM, FT-IR, and XPS. The Ag nanoparticles with an average particle size of 20 nm are decorated on the surface of graphene in uniform and regular stacks, while the graphene nanosheets exist as an exfoliation state in Ag-graphene nanocomposite. The tremendous intensity decrease of the C-O and C=O XPS peaks and the disappearance of FT-IR band around 1730 cm~(-1) for Ag-graphene nanocomposite suggest that the graphite oxide has been reduced into graphene. Electrochemical properties are characterized by cyclic voltammetry and electrochemical impedance spectroscopy in 2.0 mol L~(-1) KNO_3 electrolyte. Ag-graphene nanocomposite electrode shows a characteristic Faradic capacitance behavior, and the specific capacitance value is 220 Fg~(-1) at a scan rate of 10mVs~(-1), which is much higher than that of the graphene electrode (140 Fg~(-1)). The high capacitance is ascribed to the large pseudocapacitance from the residual C-O and C=O function groups, high electrical conductivity, and less aggregation of the graphene nanosheets due to the existence of Ag particles.