In Situ Study of Ethanol Electrooxidation on Monodispersed Pt3Sn Nanoparticles

• Published in: ChemElectroChem Vol. 1; no. 5; pp. 885 - 895
• Main Authors: Herranz, Tirma, Ibáñez, María, Gómez de la Fuente, José L., Pérez‐Alonso, Francisco J., Peña, Miguel A., Cabot, Andreu, Rojas, Sergio
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY‐VCH Verlag 13.05.2014
• Subjects: ethanol; fuel cells; mass spectrometry; nanoparticles; platinum
• ISSN: 2196-0216; 2196-0216
• DOI: 10.1002/celc.201300254

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 in situ 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. Oxidation or scission, that is the question: Pt3Sn nanosized particles are rather active for the electrooxidation of ethanol in acid medium to produce more acetic acid and acetaldehyde than on Pt. However, the production of CO2 and other C1 species is less than that on Pt. The more facile formation of adsorbed OH species on Pt3Sn, although vital for the oxidation of intermediates such as adsorbed CO, prevents scission of the CC bond.