Microwave heated synthesis of carbon supported Pd, Ni and Pd-Ni nanoparticles for methanol oxidation in KOH solution

Pd, Ni and Pd-Ni nanoparticles uniformly dispersed on Vulcan XC-72R carbon black are prepared by microwave-irradiation using NaBH4 as a reducing agent. Pd/C, Ni/C and Pd-Ni/C electrocatalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDX). Pd-Ni alloy was formed with an average particle size of 3 nm. Kinetic parameters such as the electron transfer coefficient value (a) and electron transfer rate constant of Ni/C and Pd-Ni/C electrocatalysts in 0.5 M KOH solution were calculated. The prepared electrocatalysts were examined for methanol oxidation in alkaline medium. The long-term stability of electrocatalysts in (0.6 M MeOH + 0.5 M KOH) solution was studied using repeated cyclic voltammetry and chronoamperometry. Two methanol oxidation peaks were observed at Pd-Ni/C at 0 and +913 mV. Their current density values are higher than those at Pd/C and Ni/C electrocatalysts by 3.84 and 1.43 times, respectively. The catalytic rate constant at Ni/C and Pd-Ni/C was estimated using double-step chronoamperometry as 1.80 x 10(3) and 5.88 x 10(3) cm(3) mol(-1) s(-1), respectively. Pd-Ni/C showed better stability performance when compared to Pd/C and Ni/C electrocatalysts. (C) 2013 Elsevier B.V. All rights reserved.