Palladium - Cobalt aerogels for ethanol oxidation: Electrochemical study of chemical ratio effects

The present work presents a simple method based on a microwave-assisted sol-gel process to obtain various PdCo aerogels. Different Pd:Co chemical ratios were used and the obtained bimetallic aerogels exhibit different physicochemical properties such as morphology, surface area, crystalline size and oxidation state of the metal components. These unsupported bimetallic aerogels present interesting properties to be used as electrocatalysts for the ethanol oxidation reaction. Samples with different compositions were electrochemically characterized in a three-electrode cell configuration towards the ethanol oxidation reaction. The result was good performance for PdCo [80:20] and PdCo [50:50] aerogels in terms of current density and reaction potential, respectively. The series of aerogels were also tested as anodes in a real device such as a hybrid (acid-alkaline) microfluidic fuel cell for ethanol oxidation reaction, and the PdCo [80:20] aerogel was found to be the most effective electrocatalyst with 68 mW cm-2 and 227 mA cm-2 as power density and current density, respectively. The results revealed that the electrochemical performance of this unsupported electrocatalyst is even better than that of the Pd aerogel alone, since the synergies with the transition metal Co are minimized in addition to the use of the noble metal.