Large level of N-doped graphene prepared by facile route with high supercapacitance.

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A single material that can perform water oxidation and oxygen reduction reactions (ORR), also called bifunctional catalyst, represents a novel concept that emerged from recent materials research and that has led to applications in new‐generation energy‐storage systems, such as regenerative fuel cells. Here, metal/metal‐oxide free, doped graphene derived from rhombohedral boron carbide (B4C) is demonstrated to be an effective bifunctional catalyst for the first time. B4C, one of the hardest materials in nature next to diamond and cubic boron nitride, is converted and separated in bulk to form heteroatom (boron, B) doped graphene (BG, yield ≈7% by weight, after the first cycle). This structural conversion of B4C to graphene is accompanied by in situ boron doping and results in the formation of an electrochemically active material from a non‐electrochemically active material, broadening its potential for application in various energy‐related technologies. The electrocatalytic efficacy of BG is studied using various voltammetric techniques. The results show a four‐electron transfer mechanism as well as a high methanol tolerance and stability towards ORR. The results are comparable to those from commercial 20 wt% Pt/C in terms of performance. Furthermore, the bifunctionality of the BG is also demonstrated by its performance in water oxidation.

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.

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