In situ study of ethanol electrooxidation on monodispersed Pt inf 3 inf Sn nanoparticles

Monodispersed Pt3Sn nanoparticles were prepared through a mild thermal synthesis in the presence of surfactants. The performance of Pt3Sn for the electrooxidation of ethanol and adsorbed carbon monoxide (COad) in acid medium was studied by a combination of electrochemical and insitu spectroscopic methods, namely, infrared reflection absorption spectroscopy and differential electrochemical mass spectrometry (DEMS), and the results were compared to those obtained with the use of Pt black. The formation of the Pt3Sn solid solution promoted the oxidation of COad at less-positive potentials than those required for Pt black. Also, the electrooxidation of ethanol, especially at lower potentials, was more favorable with Pt3Sn, as deduced from the higher faradaic currents recorded during the ethanol oxidation reaction (EOR). However, the distribution of products as deduced by DEMS analysis suggested that the formation of C1 products, CO2 inclusive, is less significant on Pt3Sn than on Pt. In fact, the higher faradaic current recorded with the former catalyst can be attributed to the greater amounts of acetaldehyde and acetic acid formed. After the EOR, the surface of both Pt and Pt3Sn remained covered by ethanol adsorbates. Whereas C2 fragments were the main adsorbates at the surface of Pt3Sn after the EOR, both C1 and C2 species remained adsorbed at Pt black.