Microwave-assisted pechini synthesis of Pd-Ni nanocatalyst for ethanol electro-oxidation in alkaline medium

Abstract

Fuel cells provide a means for the direct conversion of fuels to electricity. Direct alcohol fuel cells (DAFCs) are particularly attractive because liquid fuels such as methanol or ethanol have a relatively low cost, a high volumetric energy density, and they are easily handled and stored. Ethanol is not only less toxic than methanol, but can be produced from renewable resources, which makes it a promising fuel. Alkaline DAFCs also have the potential for better oxygen reduction kinetics than their acidic counterparts. For these reasons, electrocatalysts for the oxidation of ethanol in alkaline medium deserve special attention. Pd and its alloys, e.g. Pd-Ni, have been investigated widely as catalysts for ethanol electro-oxidation, and form the subject of this paper. Although Pd-Ni nanocatalysts have been well reported, there is no report on the use of the so-called Pechini method to prepare them. The Pechini process is based on a sol-gel route whereby an aqueous solution of suitable oxides or salts is mixed with an alpha-hydroxycarboxylic acid such as citric acid and a polyhydroxy alcohol such as ethylene glycol. Upon heating, a polymer matrix forms and the metal is at least partially reduced. The result, after pyrolysis of the polymer, is a finely dispersed metal (or metal oxide), as is typically required for catalysis. Microwave treatment has been used on a wide range of chemical reactions, including catalyst synthesis. However, no report could be found of its use in conjunction with the Pechini synthesis of Pd-Ni electrocatalysts for ethanol oxidation. This presentation will describe, for the first time, the synthesis of a Pd-Ni nanocatalyst using a microwave-assisted Pechini method. Importantly, the impact of microwave irradiation on the structure of the Pd-Ni nanocatalyst as well as its electrocatalytic behaviour towards the oxidation of ethanol in alkaline medium will be discussed.