Graphene-Supported Pt–Au Alloy Nanoparticles: A Highly Efficient Anode for Direct Formic Acid Fuel Cells

Abstract

Graphene-supported Pt and Pt–Au alloy electrocatalysts are prepared by ethylene glycol reduction method and characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDX). XRD reveals the face-centered cubic structure of Pt in the materials. SEM and TEM images show the good spatial distribution of metal nanoparticles on layered graphene sheets. EDX reveals that the average composition of elements in the Pt–Au alloy catalyst is approximately 1:1. Electrocatalytic performance of the prepared materials toward formic acid oxidation (FAO) is investigated using cyclic voltammetry. FAO activity of the Pt–Au/graphene is found to be ten times higher than that of Pt/graphene. The prepared electrocatalysts are used as anode in a direct formic acid fuel cell and tested at 303 and 333 K. An increase in the performance with increasing temperature is observed. A maximum power density of 185, 70, and 53 mW/cm2 is observed with Pt–Au/graphene, Pt/graphene, and commercial Pt/C anodes, respectively, at 333 K. The high electrocatalytic performance of Pt–Au/graphene is attributed to the change in the electronic structure of Pt by the presence of alloying element, Au.