Synthesis, Characterization, and Electrocatalytic Activity of PtBi and PtPb Nanoparticles Prepared by Borohydride Reduction in Methanol

Intermetallic compounds PtPb and PtBi have been prepared in nanoparticle form by dissolving Pt and Pb or Bi precursors in anhydrous methanol and coreducing the metal precursors with sodium borohydride. The average domain size determined from pXRD is 10 nm. The particles have been characterized by pXRD, SEM, STEM, EDX, and CBED. SEM and STEM images show the particles to be aggregated, forming clusters and chains. The BET surface area of the nanoparticles was measured using Kr as the adsorbing gas. The electrocatalytic oxidation of formic acid and methanol by the as-prepared PtPb and PtBi nanoparticles has been studied by rotating disk voltammetry for potential fuel-cell applications. The PtPb and PtBi nanoparticles displayed enhanced electrochemical activity toward formic acid and methanol oxidation when compared to commercially available Pt and PtRu nanoparticles. The electrocatalytic activity of the PtPb nanoparticles was studied as a function of sonication time of the catalyst ink, and morphology changes were followed by scanning electron microscopy. The results showed that the activity of the catalyst initially increased with sonication time and then decreased.