Graphene Supported Silver Nanocrystals Preparation for Efficient Oxygen Reduction in Alkaline Fuel Cells

The silver nanocrystals (AgNCs) anchored on graphene oxide (GO) catalysts have been synthesized by a facile chemical reduction and nontemplate method using ascorbic acid (AA) as reducing agent and have successfully employed as a cathode catalyst for oxygen reduction reaction (ORR) in direct alkaline fuel cells (DAFCs). The morphological characterizations demonstrate that the AgNCs have crystalline form and grafted onto reduced graphene oxide (AgNCs/rGO_AA). Comparatively better dispersion and higher population of AgNCs have observed on AA treated AgNCs/rGO than NaBH 4 which is known as conventional reducing agent. The electrochemical catalysis in 0.1 M KOH electrolyte has demonstrated that the AgNCs/rGO_AA has an excellent electrocatalytic activity for ORR in alkaline media compared to the other tested electrodes. Particularly, it shows 40% higher mass activity with large specific activity against 20 wt% Pt/C with faster electron transfer rate per O 2 . Moreover, the reaction kinetic parameters have confirmed that the ORR at AgNCs/rGO_AA catalyst not only follows a 4e − process with lowering H 2 O 2 formation but also proceeds on with good stability and fuel selectivity in DAFCs.