Graphene quantum dots decorated Ag-MnO2 elecro-catalysts for oxygen reduction reaction in alkaline media

Electrocatalysts for oxygen reduction reaction (ORR) play a fundamental role because this reaction is very slow. In this paper, we synthesis of Ag-MnO2 catalyst by electro deposition method and preparation of graphene quantum dots (GQDs) by hummer method and then we prepared composite of GQDs@Ag-MnO2 and we investigated behaviour of composite for ORR. Also, this composite was compared with Ag-MnO2 and showed better performance against Ag-MnO2. The performance of both catalyst was considered with linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS) and choronoamperometry (CA) of catalysts in 0.5 M KOH solution. The cathodic current density of GQDs@Ag-MnO2 was 6.74 mA/cm2 while the cathodic current density of Ag-MnO2 was 3.60 mA/cm2. CA for both two catalyst was showed the same durability and EIS for GQDs@Ag-MnO2 was showed that GQDs enhanced the electrical conductivity of composite and low electrochemical charge transfer resistance was obtained on the GQDs@Ag-MnO2 electrode compared with Ag-MnO2.