Electrocatalytic activity of ordered intermetallic PtPb nanoparticles prepared by borohydride reduction toward formic acid oxidation

The electrocatalytic activity of nanoparticles of the ordered intermetallic compound PtPb toward the oxidation of formic acid (FA) for potential fuel cell applications has been studied using cyclic voltammetry, rotating disk electrode voltammetry, and chrono-amperometry. The PtPb nanoparticles were prepared by dissolving Pt and Pb precursors in anhydrous methanol, and co-reducing with sodium borohydride (NaBH4). When the activity of PtPb nanoparticles was compared to that of commercially available Pt, Pd, and Pt-Ru/Vulcan alloy nanoparticles for the oxidation of FA, the PtPb nanoparticles exhibited superior electrocatalytic activity in terms of oxidation onset potential (-0.18 V vs Ag/AgCl) and mass activity (0.13 mA mu g(-1) at +0.2 V) in 0.5 M FA and 0.1 M sulfuric acid (H2SO4) solution. In addition, the PtPb nanoparticles exhibited larger heterogeneous charge-transfer rate constants and significantly enhanced tolerance to poisoning by carbon monoxide (CO) and sulfur-containing compounds. At low applied potential (E = 0.0 V), a stable oxidation current for FA oxidation could be observed for 9 h, compared to a large decrease in oxidation current, ostensibly due to CO poisoning, on Pt, Pd, and Pt-Ru/Vulcan alloy nanoparticles. (c) 2007 The Electrochemical Society.