Synthesis of Pt-Mo/WMCNTs Nanostructures Reduced by the Green Chemical Route and Its Electrocatalytic Activity in the ORR

Abstract

Platinum (Pt) and molybdenum (Mo) nanoparticles were supported on multiwall carbon nanotubes (MWCNTs) by a green chemical route. Different relations of Pt:Mo (10:0, 8:2, 5:5, 2:8, and 0:10, respectively) in weight percent were compared to their electrocatalytic activity in the oxygen reduction reaction (ORR) in an acid medium. The morphologies and the structure were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The rotary disc electrode (RDE) and linear voltammetry (LV) techniques were employed to observe the electron transfer and mass transport phenomena. The surface activation of the samples was conducted by cyclic voltammetry (CV) technique According to the TEM analysis. The TEM analysis, shows that Mo and Pt nanoparticles have a good dispersion on the tubular carbon support, with sizes between 3.94 and 10.97 nm. All Pt-containing ratios had exhibited a first-order transfer in the ORR without inhibition of the reaction. Molybdenum is a reducing agent (oxyphilic metal) that benefits the adsorption of oxygenated species. The Pt:Mo 8:2 wt.% ratio presents the maximum benefits in the kinetic parameters. The Mo10/MWCNTs nanostructure inhibits the ORR due to the strong bonds it presents with oxygen. Molybdenum at low concentrations with platinum is conducive to oxygen molecule adsorption-desorption by increasing the ORR’s electroactivity.