Preparation of Pd-Modified Ni Foam Electrodes and Their Use as Anodes for the Oxidation of Alcohols in Basic Media

Pd-modified Ni foam electrodes were prepared by a spontaneous deposition method. Ni foam samples were immersed in acid PdCl2 solutions for different durations (t(SD)). The Pd loading and the surface area of the Pd deposits were determined as a function of [PdCl2] and t(SD). SEM-EDX showed that Pd deposits were homogeneously formed on the walls of both the outer and the inner cells of the Ni foam. Pd-modified Ni foam electrodes were used as anodes for the oxidation of methanol, ethanol, ethylene glycol, and glycerol in basic media. Voltammetric curves for the oxidation of alcohols showed that the peak current increased with increasing Pd loading in a sub-linear way. For the lowest loading explored (ca. 1 mg of Pd in a 1 cm(3) foam volume), the peak current per unit Pd mass was of the order of 650 Ag-1 for 0.5 M methanol and ethanol, ca. 1,500 Ag-1 for glycerol and higher than 2,000 Ag-1 for ethylene glycol.