Synthetic Procedures to Pd-Based Electrocatalysts for Alcohol Oxidation

Current synthetic methods for the preparation of Pd-based electrocatalysts for anodes of DAFCs are manifold, including reduction of high-valent metal compounds with chemical agents, colloidal metal deposition, electrodeposition and transmetalation 

A large variety of conductive materials have been used to support Pd nanoparticles prepared by electroless procedures, these include carbon blacks like Vulcan XC-72, alone or in com- 

Common techniques for the characterization of the electrocatalysts include High Resolution Electron Microscopy (HRTEM), Extended X-ray Absorption Fine Stracture Spectroscopy (EXAFS), Energy Dispersive Spectroscopy (EDS), Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES), Near Edge X-ray Absorption Spectroscopy (XANES), X-Ray Powder Diffraction (XRPD), Infrared and Raman Spectroscopy (IR, RS). 

The metal particles obtained by electroless procedures are generally well dispersed and crystalline with dimensions in the range from 3 to 25 run, while the XRPD patterns show face-centered cubic (fee) lattice struemres with diffraction peaks at the Bragg angles of 40.10°, 46.40° and 68.08°, corresponding to the (111), (200) and (220) facets of palladium crystal. Typical TEM micrographs and XPRD patterns of Pd nanoparticles supported on 

Electrochemical methods for the preparation of anode electrocatalysts for DAFCs involve either the electrodeposition of one metal at a time, eventually followed by the electrodeposition of other metals, or the contemporaneons electrodeposition of two or more metals. Highly ordered Pd nanowires arrays (Fig. 5) have been prepared by template-electrodeposition on glassy carbon electrodes, while cyclic potential sweep techniqnes have been used to prepare Pd thin films on polyciystalline Pt or An substrates. Ni-Pd electrodes for methanol oxidation have been prepared by electrodeposition onto titaninm discs nsing a PdCl2/NiS04-7H20 bath.  

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