Carbon-supported Pt-free catalysts with high specificity and activity toward the oxygen reduction reaction in acidic medium

Abstract

Specific carbon-supported Pt-free catalysts (Pd, PdFe, PdIr and PdFeIr) toward the oxygen reduction reaction (ORR) were developed. With this end, materials with high and low activity toward the ORR and the methanol oxidation reaction (MOR) were synthesized by the borohydride method (BM). Physicochemical characterization was carried out by several x-ray techniques, such as x-ray photoelectron spectroscopy (XPS), x-ray diffraction (XRD) and x-ray dispersive energy (EDX). The ORR was studied at these materials in absence and presence of methanol in acidic medium in a half-cell configuration by the rotating disk electrode (RDE) technique. Additionally, the performance of the catalysts was evaluated as cathode material in a direct methanol fuel cell (DMFC) station. Main results indicate enhanced catalysis toward the ORR and improved tolerance toward the methanol by Fe and Ir insertion into the material, respectively. Membrane electrode assembly (MEA) with a cathode containing PdFeIr/C catalyst yields elevated performance in DMFC, while the electrode cost is dramatically reduced.