Preparation and Characterization of Nanostructured Electrodes by Electrophoretically Co-deposition of Pd and Pt Nanoparticles

A novel Pd-doped Pt/Ti nanostructured electrode was prepared by the electrophoretic co-deposition of Pt and Pd nanoparticles on a Ti support in a reverse micellar solution of water/Aerosol OT/isooctane, followed by a heat treatment in air at 400 °C. The total catalyst loading (Pt and Pd) was fixed at 0.015 mmol/cm^2, referred to the geometric area. The crystal structure, surface morphology, and elemental distribution of the resultant electrode were characterized by XRD, SEM, and SEMWDS, respectively. The surface composition and electrocatalytic activity of the electrode were investigated by cyclic voltammetry in a solution of 0.5 M H2SO4 and a mixed solution of 0.1 M CH3OH and 1.0 M NaOH, respectively. The composition on the electrode surface could be controlled by adjusting the composition of the electrodeposition solution. Also, with increasing the Pd content on the electrode surface, the electrocatalytic activity of the Pd-doped Pt/Ti nanostructured electrodes for the oxidation of CH3OH first increased, and then decreased after reaching a maximum at a surface composition of 20 atom % Pd. When the Pd content on the electrode surface was larger than 60%, the electrocatalytic activity of the Pd-doped Pt/Ti nanostructured electrode was lower than that of the Pt/Ti electrode because most active sites were occupied by the relatively inactive Pd. This result revealed that the activity enhancement or diminution resulted from the doping of Pd in Pt at an atomic level might be achieved via the interaction between Pt and Pd nanoparticles. In addition, at a surface composition of 20 atom % Pd, the current density at 25 ° C was 55 mA/cm^2, revealing that the resultant electrode had a rather high current density and specific activity.