Ethanol electro-oxidation on partially alloyed Pt-Sn-Rh/C catalysts

• Published in: Electrochimica acta Vol. 147; pp. 483 - 489
• Main Authors: de Souza, Elson A., Giz, M.Janete, Camara, Giuseppe A., Antolini, Ermete, Passos, Raimundo R.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 20-11-2014
• Subjects: electrocatalysis; Ethanol electro-oxidation; in-situ IRRAS; Pt-Sn-Rh/C; supported catalysts; Ethanol electro-oxidation; supported catalysts; electrocatalysis; Pt-Sn-Rh/C; in-situ IRRAS
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2014.09.141

Ternary Pt-Sn-Rh/C catalysts of Pt:Sn:Rh=1:0.8:0.2 and 1:1:0.33 atomic ratios were synthesized using the formic acid method and their electrochemical activities were compared for ethanol oxidation with that of binary Pt-Sn/C (1:1) and Pt-Rh/C (1:0.11) catalysts. XRD analysis indicated the presence of Sn in both alloyed and oxide form and suggested the formation of a ternary Pt-Sn-Rh alloy in both catalysts. The particle size by TEM was around 3.5nm for all catalysts. The efficiency for Pt utilization increased with Rh content. Pt-Sn-Rh/C catalysts exhibited higher catalytic activity for ethanol oxidation than Pt-Rh/C, but lower than Pt-Sn/C. Among ternary catalysts, Pt-Sn-Rh/C (1:0.8:0.2) was the most active. In situ IRRAS showed Rh plays a dual counteracting role during ethanol electro-oxidation on Pt-Sn-Rh/C catalysts, once it promotes C-C bond breaking, thus favouring CO2 formation, but hinders adsorption of ethanol, decreasing the production of acetic acid.