Pt decorated PdAu/C nanocatalysts with ultralow Pt loading for formic acid electrooxidation

Abstract

Understanding how the pathway of formic acid electrooxidation depends on the composition and structure of Pt or Pd atoms on the surface of Pd- or Pt-based nanoparticles is important for designing catalysts aiming toward active, selective, stable, and low-cost. This work reports new findings of the investigation of submonolayer Pt decorated PdAu/C nanocatalysts (donated as Pt-PdAu/C) for formic acid electrooxidation. The Pt-PdAu/C are synthesized via a spontaneous displacement reaction and characterized by an array of analytical techniques including transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The electrocatalytic activity is examined using cyclic voltammetric and chronoamperometric measurements. The results show that the as-prepared Pt-PdAu/C with an optimal Pt:Pd atomic ratio of 1:100 exhibits enhanced electrocatalytic activity for formic acid electrooxidation compared with the PdAu/C and commercial the Pt/C catalysts. The oxidation potential on the Pt-PdAu/C shifts negatively by about 200 mV compared with that of the PdAu/C. The enhanced electrocatalytic activity and stability are attributed to the replacement of the Pd atom layer by Pt atoms, which significantly reduces the presence of the so-called "three neighboring site" of Pd or Pt atoms in the Pt-PdAu/C to efficiently suppress CO formation. The enhanced activity/stability and ultralow Pt loading of the Pt-PdAu/C have implications to the development of commercially-viable catalysts for application in direct formic acid fuel cells and catalysis.