Polymer-assisted electrophoretic synthesis of N-doped graphene-polypyrrole demonstrating oxygen reduction reaction with excellent methanol crossover impact and durability.

The design and synthesis of the metal-free catalysts having superior electrocatalytic activity, high durability, low cost and under mild conditions is extremely desirable but remains challenging. To address this problem, we report a polymer assisted electrochemical exfoliation technique of graphite in the presence of aqueous acidic medium. This simple, cost-effective and mass scale production approach could open a possibility for the synthesis of high-quality nitrogen doped graphene-polypyrrole (NG-PPy). The NG-PPy catalyst displays an improved half wave potential (E1/2 = 0.77 V) in alkaline medium than G-PPy (E1/2 = 0.66 V). Most importantly, this catalyst demonstrating excellent stability with high methanol tolerance, which is outperforming the commercial Pt/C catalyst and few other previously reported metal-free catalysts. The content of graphitic nitrogen atoms is the key factor for the enhancement of electrocatalytic activity towards oxygen reduction reactions (ORR). Interestingly, the NG-PPy catalyst is used as a cathode material in a zinc-air battery, which demonstrates a higher peak power density (59 mW cm-2) than G-PPy (36.6 mW cm-2), which is broadcasting the importance of the low-cost material synthesis approach towards the development of metal-free efficient ORR catalysts for fuel cell and metal air battery applications. Remarkably, the polymer assisted electrophoretic exfoliation of graphite with high yield (~88 wt %) of few layers of graphene flakes could pave the path towards mass production of high-quality graphene for a variety of applications.