Comparative study of carbon-supported Pd and PdAg catalysts synthesised by the polyol process and reverse micelles methods

Carbon-supported Pd and PdAg nanoparticles were synthesised by the polyol (P) and reverse micelles (RM) methods for use in a comparative study as catalysts for ethanol electro-oxidation in alkaline media. The electrocatalysts were physically and chemically characterised by transmission electron microscopy, X-ray diffraction and thermogravimetric analysis. Electrochemical characterisation was performed by cyclic voltammetry in the absence and presence of ethanol (0.1, 1, 3 M ethanol), chronoamperometry and electrochemical impedance spectroscopy. The electrochemical measurements showed that the catalysts obtained by the RM method presented excellent dispersion and small crystal size, resulting in materials with high electro-active area. However, the PdAg/C catalysts prepared by the polyol process presented better catalytic activity and stability during the electro-oxidation reaction. In addition to the excellent dispersion and low agglomeration promoted by the polyol method, catalytic enhancement can also be associated with the synergic effect between Pd and Ag elements.