Paper SS-TuP19
Combined Surface Analysis and Electrochemistry Studies on SnO₂-Pt and Sn-Pt Electrocatalysts for Ethanol Oxidation Reaction

Tuesday, October 19, 2010, 6:00 pm, Room Southwest Exhibit Hall

Recently, the ethanol electro-oxidation reaction has attracted considerable attention because of the advantages of using ethanol as fuel in liquid fuel cells.¹ Ethanol can be produced from renewable biomass sources, and has high energy density and less toxic than methanol. However, the ethanol oxidation kinetics is slow, impeding its use in the direct ethanol fuel cells (DEFCs). Tremendous efforts have been made to develop new ethanol oxidation catalysts to improve its efficiency. Binary Pt-Sn alloy catalysts are some of the more extensively investigated anode materials for DEFCs. It was found that the increased activity of binary electrocatalysts with respect to Pt alone was attributed to the bifunctional effect and electronic interaction between Pt and alloyed metals.^2,3,4 However, studies from supported nanocatalyst show disagreements in mechanism of what degree of alloying between Pt and Sn and what amount of Sn alloyed with Pt will improve the activity of the electrocatalysts towards EOR. ^{5, 6, 7, 8} It is still unclear whether the alloyed Sn, or the SnO₂ phase is the reason in the increase in Pt-Sn electrocatalysts activity towards EOR.^{1, 5-8}

In the work presented here, we are investigating surface alloy of Pt-Sn/Pt(111) and SnO2/Pt(111) as model catalysts for ethanol electro-oxidation. Characterization is performed by a combination of surface science techniques (X-Ray photoelectron spectroscopy (XPS), low energy electron diffraction (LEED), temperature programmed desorption (TPD), and low energy ion scattering spectroscopy (LEISS)) and classical electrochemical measurements. This integrated approach can be used to identify the fundamental properties of SnO₂/Pt(111) and Sn-Pt/Pt(111) electrodes and to correlate them with the activity of each electrode towards EOR.

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