One-pot synthesis of ultrasmall Pt-Ag nanoparticles decorated on graphene as a high-performance catalyst toward methanol oxidation

A one-pot synthesis method is utilized for the fabrication of ultrasmall platinum-silver nanoparticles decorated on graphene (Pt-Ag/G) catalyst. This method has several advantages such as inexpensiveness, simplicity, low temperature, surfactant free, reductant free, being environmentally friendly and greenness. In this work, graphene and silver formate were dispersed in ultrapure water in an ultrasonic bath at 25 degrees C followed by through a galvanic displacement reaction; to prepare Pt-Ag/G, PtCl2 was added to the suspension under mild stirring condition. The morphology, crystal structure and chemical compositions of the as-fabricated Pt-Ag/G and Pt/C catalysts were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and Energy dispersive X-ray spectroscopy (EDS) techniques. Electrochemical techniques, including cyclic voltammetry (CV) and chro-noamperometry (CA) measurements were used to analyze the electrochemical activity of the Pt-Ag/G and Pt/C catalysts. The TEM images illustrate the uniform distribution of ultrasmall Pt-Ag nanoparticles with the average size of 2-3 nm on the graphene nanosheets. The Pt-Ag/G promoted the current density 2.46 times as much as Pt/C with a negative shift in onset oxidation potential and peak potential for oxidation reaction of methanol. Besides, the novel Pt-Ag/G catalyst shows large electrochemically active surface area, lower apparent activation energy, and higher levels of durability in comparison to the Pt/C catalyst for the oxidation of methanol. The Pt- Ag/G catalyst depicts extraordinary catalytic performance and stability to those of the Pt/C catalyst toward methanol oxidation in alkaline media. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.