Pd black decorated by Pt sub-monolayers as an electrocatalyst for the HCOOH oxidation

Abstract

Pd black was modified by a very low amount of Pt corresponding to a sub-monolayer (ML). Spontaneous displacement method was employed. The catalysts with 0.02-0.12 ML were characterized by cyclic voltammetry and COads stripping and were tested for HCOOH oxidation under the potentiodynamic and potentiostatic conditions. All the Pt"Pd catalysts were more active for HCOOH oxidation than Pd black. The Pt"Pd with 0.08 ML of Pt exhibited the highest activity with the maximum current density under the potentiodynamic conditions of 8 mA cm(-2) (vs. 2.7 mA cm(-2) on Pd black). Contrasting HCOOH oxidation kinetics on Pt"Pd and Pt"Au catalysts revealed that the current densities are higher, and the poisoning rate is lower on Pt"Pd catalyst. This was ascribed to an optimal strength of the Pt-adsorbate bond when Pt is supported on Pd and to a possible influence of the Pt atoms on the Pd substrate.