Carbon-nitrogen/graphene composite as metal-free electrocatalyst for the oxygen reduction reaction

Sheet-like carbon-nitrogen (CN (x) )/graphene composites with a high content of nitrogen (x a (c) 1/2 0.15) was prepared by the carbonization of polypyrrole (PPy)/reduced-graphene-oxide (rGO) composite at 600-800A degrees C. We used rGO instead of graphene oxide (GO) sheets as a template and a substrate to immobilize PPy since the PPy/GO composite agglomerates easily because of the dehydration of excess oxygen-containing groups on the GO sheets during the drying process. The dried PPy/rGO intermediate and its derived CN (x) /graphene products retain their high dispersion and loose-powder features. The as-prepared CN (x) /graphene composites have a total nitrogen content of about 10 at% and their nitrogen state is mainly of pyridinic and graphitic type. CN (x) /graphene composites exhibit excellent performance for the oxygen reduction reaction (ORR) in terms of electrocatalytic activity, stability and immunity towards methanol crossover and CO poisoning, suggesting their potential as metal-free electrocatalysts for the ORR.