Facile Synthesis of High Performance Platinum-Cerium Oxide Nanocatalysts for Methanol Oxidation

Abstract

Electrooxidation of methanol has been studied intensively in the scientific community, and various catalysts have been developed for direct methanol fuel cells. In this study, platinum-cerium oxide nanoparticles have been synthesised, exhibiting high activity towards methanol electrooxidation. The materials were electrochemically characterised using rotating disk electrode, cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy methods. Scanning electron microscopy, X-Ray diffraction, inductively coupled plasma mass spectrometry and BET surface area mesurements were performed to characterise the physical properties of the synthesised materials. The methodology of the synthesis of the materials was straightforward and resource efficient. The synthesised nanocatalysts have a very uniform dispersion on the catalyst support material, and a narrow size distribution. Even at low platinum loadings, the materials have a lower overpotential towards methanol oxidation than commercial Pt-Vulcan catalysts. Based on cyclic voltammetry measurement data, the peak potential for the synthesised materials was 40 mV more negative than for the commercial material in the anodic potential scan, and 60 mV more negative in the cathodic potential scan. In addition to the high currents for methanol oxidation, extremely high currents were achieved in the cathodic potential sweep, in the region attributable to the oxidation of carbon monoxide. Methanol and carbon monoxide poisoning of the nanocatalysts was unnoticeable during the experiments. The results of the study lay a promising foundation for the investigation of nanocatalysts containing other rare earth metal oxides, as well as to the investigation of the electrooxidation of ethanol or other organic fuels on composite catalysts. Acknowlegements The authors wish to thank P. Paiste for ICP-MS measurements and J. Aruväli for XRD measurements This work was supported by the EU through the European Regional Development Fund TK141, the institutional research funding project IUT20-13 of the Estonian Ministry of Education and Research, the Estonian Energy Technology Program Project No. SLOKT10209T, Estonian Materials Technology project 3.2.1101.12-0019, Estonian Center of Excellence in Science Project TK117T, grant ETF9352 and PUT55.