Facile synthesis of Pt nanoparticles loaded porous graphene towards oxygen reduction reaction

Abstract

A facile method was developed to fabricate Pt nanoparticles loaded porous graphene (Pt-PGR) composites via impregnation and reduction. The PGR was first immersed into a H2PtCl6 ethanol solution, and then the H2PtCl6 was reduced to Pt nanoparticles with NaBH4 to produce the Pt-PGR composites. Morphologies and composition of the Pt-PGR composites were characterized by filed-emission scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and nitrogen physisorption. It was found that the obtained Pt-PGR composites had three-dimensional interpenetrating porous structure, and the Pt nanoparticles from 50 to 150nm uniformly distributed on the graphene surfaces. Electrochemical and electrocatalytical properties of the Pt-PGR composite were investigated by cyclic voltammogram and linear sweep voltammogram. The results indicated that the Pt-PGR composites had excellent catalytical activity towards the oxygen reduction reaction (ORR), and showed the higher diffusion-limited current densities (4.0mAcm−2 and 25mAmgpt−1 at −0.6V) and stability compared with the commercial 20% Pt/C catalyst. The electrocatalytical kinetics experiments showed that the electron transfer number was 3.6 calculated from the Koutecky-Levich plot, indicating an approximate four-electron process and the oxygen directly reduced to water for the ORR.