Pt_7Sn_3 Catalysts for Ethanol Electro-Oxidation: Correlation Between Surface Structure and Catalytic Activity

摘要

X-ray photoelectron spectroscopy has been chosen to study the surface chemistry of carbon-supported PtSn catalysts of 70:30 at.% composition. Correlation of XPS structural information with catalytic performance for ethanol electro-oxidation in acidic solution, average particle size and structural characteristics is accomplished by application of multivariate statistical methods of data analysis (MVA). From structure to property correlations it was found that the best performing electrocatalysts do not have largest absolute amounts of Pt and Sn on the surface, whereas samples with largest amount of total Pt and Sn have the worst catalytic activity. It is shown that relative distribution of types of Pt and Sn is more important than the absolute amounts. Samples showing the highest current densities have small amounts of both metals, but have largest relative amount of both metallic Pt and metallic Sn. The same best performing samples have fewest amounts of all types of oxides, i.e. PtO, PtO_2 and SnO_x.