Nitrogen Doped Graphene as Metal Free Electrocatalyst for Efficient Oxygen Reduction Reaction in Alkaline Media and Its Application in Anion Exchange Membrane Fuel Cells

Abstract

High cost of benchmarked platinum-based electro-catalyst restricts their extensive usage in various energy technologies such as fuel cell. To overcome this, we report a simple, economical and facile synthesis route for a series of edge-defective nitrogen doped graphene (NG) from graphene oxide in the presence of melamine as a nitrogen precursor. The oxygen reduction reaction activity of NG in alkaline medium is studied with varying GO to melamine ratio to optimize the N-content in the graphene sheet. Cyclic voltammograms and linear sweep voltammograms have been recorded in N2/O2 saturated 0.1 M aqueous KOH electrolyte. It is observed that N-doped graphene exhibits a favorable formation of hydroxide ions through a four electron transfer process as confirmed from both rotating disk and rotating ring-disk electrode measurements. The stability of the optimized NG catalyst is ascertained by cycling the potential between −0.8 and 0.2 V vs. Ag/AgCl upto10,000 potential cycles and found to have better durability in comparison to the commercial Pt/C catalyst. The resultant N-doped graphene is used as cathode catalyst for fabricating membrane electrode assembly (MEA) and the performance is evaluated in an anion exchange membrane fuel cells (AEMFCs) at 60°C under ambient pressure.