Synthesis of nitrogen-doped graphene supported Pt nanoparticles catalysts and their catalytic activity for fuel cells

• Nitrogen-doped graphene was prepared by pyrolysis of graphene oxide, with cyanamide as the nitrogen-containing precursor, at various temperatures,
• Pt nanoparticles were well dispersed on the N-G surfaces, with small particle sizes and narrow size distributions, ranging from 1 to 5 nm.
• Improved electrocatalytic activity can be ascribed to the optimized dispersion and smaller particle sizes.

In this work, we have developed an efficient approach to prepare the nitrogen-doped graphene supported Pt nanocomposites (Pt/N-G). Nitrogen-doped graphene (N-G) was prepared by pyrolysis of graphene oxide with cyanamide as nitrogen containing precursor at different temperatures, which led to high and controllable nitrogen contents. Subsequently, the Pt nanoparticles were dispersed over N-G surface by modified chemical polyol reduction process. The morphology and nanostructure of as-prepared catalysts were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD), which verified that the Pt nanoparticles were uniformly dispersed over N-G surface with a narrow size distribution. The functional groups on the surface of the catalysts were investigated by the Fourier transform infrared spectra (FT-IR), while the elemental composition and nitrogen bonding configurations in N-G were further evaluated by X-ray photoelectron spectroscopy (XPS). Furthermore, electrochemical properties are studied by cyclic voltammetry (CV). The Pt/N-G catalysts showed the superior electrocatalytic activity toward methanol oxidation compared to that of Pt loaded on undoped graphene (Pt/G). The results suggested that N-G could be used as an effective catalyst support for fuel cell application.

Pt/N-G nanocatalysts were successfully prepared, and investigated using various techniques. The results showed that the Pt nanoparticles were well dispersed on the N-G surfaces, with small particle sizes and narrow size distributions, ranging from 1 to 5 nm. Enhancements of the reactive surface area and specific peak current densities in methanol oxidation for the Pt/N-G catalysts, compared with the Pt/G catalyst, were obtained. The improved electrocatalytic activity can be ascribed to the optimized dispersion and smaller particle sizes induced by nitrogen doping.Figure optionsDownload as PowerPoint slide