Comparative study of ethanol oxidation at Pt-based nanoalloys and UPD-modified Pt nanoparticles

Abstract

The activity of two alloys, Pt3Sn/C and Pt3Ru 2/C, was compared with the activity of Pt/C modified with corresponding amounts of SnUPD (≈25 %) and RuUPD (≈40 %) in the oxidation of ethanol. Pt3Sn/C, Pt 3Ru2/C and Pt/C catalysts were characterized by XRD analysis. To establish the activity and stability of the catalysts, potentiodynamic, quasi steady-state and chronoampe- rometric measurements were performed. Both alloys are more active than SnUPD- or Ru UPD-modified Pt/C catalysts. The electronic effect determining dominantly the activity of Pt3Sn/C is the main reason for its higher activity compared to Pt3Ru2/C. Since SnUPD and RuUPD do not provoke any significant modification of electronic environment, both modified Pt/C catalysts were less active than the corresponding alloys. More pronounced difference in activity between Pt 3Sn/C and SnUPD-modified Pt/C than between Pt 3Ru2/C and RuUPD- -modified Pt/C is caused by the electronic effect in Pt3Sn/C. The high activity of Pt 3Sn/C modified with a small amount of SnUPD (-10 %) can be explained by combining the electronic effect, causing less strongly bonded adsorbate on Pt sites and easier mobility of the SnUPD, with an enhanced amount of oxygen- containing species on the Sn sites, resulting finally in a reinforcement of the bi- functional mechanism. 2010 Copyright (CC) SCS.