Preparation of nitrogen-doped graphene supporting Pt nanoparticles as a catalyst for oxygen reduction and methanol oxidation

A novel synthesis procedure is devised to obtain nitrogen-doping graphene sheets (NGs). Initially, a conducting polymer polyaniline (PANI) is used to form a uniform coating of the polymer over graphene oxide (GO) by interfacial polymerization method for the synthesis of high-quality polyaniline-modified GO nanocomposites (PANI/GO). In polymerization, the liquid–liquid (L/L) interface provides a good soft template, which allows PANI to grow uniformly on the surface of the GO. Subsequently, thermal annealing PANI/GO nanocomposites in an inert environment lead to reduce the GO to graphene (GNs) with simultaneous nitrogen atoms incorporation in the graphene frameworks. The obtained nitrogen-doped graphene (NGs) are used as catalyst supports without any chemical modification for dispersing platinum nanoparticles (Pt NPs) by the chemical reduction method, yielding a uniform dispersion of the catalyst nanoparticles. The obtained nanocomposites are characterized by UV–Vis absorption spectra, X-ray photoelectron spectroscopy, Raman, X-ray diffraction, transmission electron microscopy, and thermogravimetric analysis. Electrochemical characterizations clearly demonstrate that the Pt/NGs nanocomposites show excellent electrocatalytic activity toward methanol oxidation and oxygen reduction. The current density of Pt/NGs is 1.58 and 1.51 times higher than that of Pt/graphene (Pt/GNs) in methanol oxidation and oxygen reduction, respectively. These results demonstrate that the Pt/NGs nanocomposites may be an attractive and advanced electrode material with potential applications for proton exchange membrane fuel cells (PEMFCs).