Fabrication of novel porous Pd particles and their electroactivity towards ethanol oxidation in alkaline media

Novel porous Pd particles (nanoPd–PEG, nanoPd–PEG–EDTA, nanoPd–HCHO–EDTA, nanoPd–EG, nanoPd–HCHO and nanoPd–EG–EDTA) were synthesized by a hydrothermal method using different reduction agents in the absence and presence of EDTA and investigated as electrocatalysts for ethanol oxidation in alkaline solutions. Results showed that PdCl2 was hydrothermally reduced to nano-scale palladium particles and a three-dimensional texture was formed for Pd particles. Presence of EDTA was favorable for the formation of Pd nanoparticles with small sizes of ca. 70 nm. Ethanol oxidation on the present Pd catalysts took place at a more negative anodic potential in 1 M NaOH solution. Among the electrocatalysts investigated, the electrocatalytic activity of the nanoPd–HCHO–EDTA was the greatest, which was characterized by the largest anodic peak current density of 151 mA cm−2 and lowest onset oxidation potential of −0.788 V (vs. SCE) for the positive scan. Very low charge transfer resistances on the nanoPd–HCHO–EDTA in 1 M NaOH containing various concentrations of ethanol were obtained according to the analysis for electrochemical impedance spectra (EIS). The prepared porous Pd catalysts were promising alternatives to Pt electrodes applied in alkaline direct alcohol fuel cells.