The Oxygen Reduction Half-reaction (ORR) at the cathode of fuel cells is a slow process even with expensive platinum-based catalysts. Therefore, development of low-cost electro-catalysts with fast kinetics for ORR is a key factor for practical application of fuel cell power. Hydrogen fuel cells provide clean energy without producing environmentally hazardous materials and their by-product is only water. Graphene-based electrocatalysts for ORR is a very attractive area of current state-of-the-art R&D activities. Herein, we report a novel method for the preparation of graphene-based material with silver nanoparticles, its characterization and possible application as an electrocatalyst for ORR of fuel cells. Graphene oxide was prepared by oxidation of Sri Lankan Natural Vein Graphite obtained from Bogala Mines, Sri Lanka which was mixed with ammoniacal silver solution and sonicated to disperse well. Then, freshly prepared extract of green tea was added to reduce both graphene oxide and Silver(I) ions, respectively, to graphene and metallic silver. Polyphenolic compounds in green tea extract act as the reducing agent. This eco-friendly method has advantages over chemical reduction method due to cost effectiveness and non-toxicity. Then the prepared silver-graphene composite material was washed and allowed to air dry. It was characterized by XRD, Raman spectroscopy and SEM. All analytical data confirm that composite contains 50 nm sized Ag nanoparticles embedded in N-doped Multi-layer graphene. Electrochemical analysis shows good electro-catalytic activity towards ORR that is higher than commercially available C/Pt at same mass loading and improved tolerance for methanol with higher durability.

Green synthesis of N-doped multilayer graphene/silver nano-particle composite using tea leave extract and its application as electrocatalyst for oxygen reduction reaction

256th National Meeting (2018)

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