Synthesis of Au-Pd Alloy Nanoparticles and Their Catalytic Activity in the Electrooxidation of Formic Acid and Lower Alcohols in Alkaline Media

Special attention was given to incorporate green chemistry into fabrication of stable Au-Pd nanoparticles and their potential applications in fuel cells. Microwave method was employed with bioconnpatible stabilizing and reducing agents to obtain Au-Pd alloy nanoparticles of average size of 5 nm diameter. The UV-vis spectroscopy helped in optimization of microwave reaction as it provided information that reaction completed in 20 s. The spherical shape, size as 5 nm and the alloy form of the nanoparticles were confirmed with the help of transmission electron microscopy, X-ray diffraction and particle size analyser. The catalytic activity of synthesized particles in electrooxidation of formic acid, methanol and ethanol in alkaline medium as model reactions in fuel cells was analyzed through cyclic voltammetry. From linear relationships between the peak current and square root of scan rate, and peak potential and log of scan rate, the electrooxidation was found to be diffusion controlled and irreversible, respectively. The current voltage characteristics improve with increase in each of electrolyte (NaOH) and fuel concentrations. However, in both the cases a saturated concentration was observed after which the current density started decreasing. The electro-active area for catalysis was found to be Au:Pd = 4:1 > 0:1 > 1:1 > 2:1.