Development of Nanostructured Metal Oxides-Platinum Electrodes for Enhanced Electrocatalytic Oxidation of Ethanol

Abstract

Ethanol is an attractive fuel for direct ethanol fuel cells (DEFCs) because it has high theoretical energy density (8.0 kWh/kg) [1], it is nontoxic and can be produced from biomass, which could make DEFCs beneficial low greenhouse gas emission power sources. Platinum is known to be the most active catalyst for the ethanol oxidation reaction (EOR). Nevertheless, at Pt catalyst, the complete oxidation of ethanol to CO2 is not attained, because of CO poisoning and the difficulty in breaking the C-C bond at low temperature, which has a detrimental effect on the fuel cell efficiency [2]. A promising strategy to improve the catalytic activity of DEFC reaction can be obtained by integrating metal oxides with Pt to form platinum-metal oxides-composites. Indeed, due to certain intrinsic properties and functions of their own, several nanostructured metal oxides (MOx) such as CeO2, SnO2, TiO2, MnO2, WOx... are emerging as a distinctive class of electrode materials in energy conversion fields. In such applications, MOx can perform as the electroactive material itself, or as a supporting matrix to enhance catalyst dispersion and its stability against sintering and particles aggregation; or advances certain electrocatalytic reactions when combined with other catalysts. In this presentation, we will discuss our recent advances in the development of nanostructured MOx-Pt catalysts anodes for low temperatures DEFCs. Both nanostructured Pt and Pt-MOx (M: Ce, Sn, Mn, Ti) composites of various surface morphologies (smooth, semi-porous and highly porous) were synthesized at room temperature by adapting and optimising the pulsed laser deposition (PLD) method. Such composites are systematically characterized with scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), microRaman spectroscopy, and transmission electron microscopy (TEM) techniques and insights into the physical interaction of MOx with Pt are discussed. Afterwards, we study the electroactivity and durability performances with post-mortem surface morphology of MOx-Pt composites as well as catalytic promoting properties of MOx to Pt towards the EOR. [1] G. Hoogers, Fuel cell technology handbook, CRC press, Boca Raton, FL, 2003. [2] F. Vigier, C. Coutanceau, F. Hahn, E.M. Belgsir, C. Lamy, J. Electroanal. Chem. 563 (2004) 81-89.