Electrochemical oxidation of ethanol on palladium-nickel nanocatalyst in alkaline media

Abstract

Pd-Ni/C catalyst was synthesized employing a borohydride reduction method. The high area Ni was first dispersed on the carbon support and then modified by Pd nanoparticles. Transmission electron microscopy confirmed relatively even distribution of Ni across the carbon support with discrete palladium particles of about 3.3 nm mean diameter on it. Cyclic voltammetry confirmed the presence of Ni on the catalyst surface. The activity of the Pd-Ni/C catalysts for ethanol oxidation reaction (EOR) in alkaline solution was tested under the potentiodynamic and potentiostatic conditions and the results were compared to those obtained on the Pd/C catalyst. It was found that Pd-Ni/C is more active for the EOR compared to Pd/C by a factor up to 3, depending on the type of experiments and whether specific activity or mass activity are considered. During the potentiodynamic stability test an interesting phenomenon of activation of Pd-Ni/C catalyst was observed. It was found that maximum activity is attained after fifty cycles with the positive potential limit of 1.2 V, regardless of whether they were performed in the electrolyte with or without ethanol. It was postulated that potential cycling of the Pd-Ni surface causes reorganization of the catalyst surface bringing Pd and Ni sites to a more suitable arrangement for the efficient ethanol oxidation.