Electro-oxidation of ethanol on Pt/C, Rh/C, and Pt/Rh/C-based electrocatalysts investigated by on-line DEMS

Autor(es)

Cantane, D. A. ^[1] ; Ambrosio, W. F. ^[1] ; Chatenet, M. ^[2] ; Lima, F. H. B. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Quim Sao Carlos, BR-13560970 Sao Carlos, SP - Brazil

^[2] U Joseph Fourier, Grenoble INP, U Savoie, LEPMI, CNRS, UMR 5279, F-38402 St Martin Dheres - France

• Tipo de documento: Artigo Científico
• Fonte: JOURNAL OF ELECTROANALYTICAL CHEMISTRY; v. 681, p. 56-65, AUG 1 2012.
• Citações Web of Science: 33

Resumo

The ethanol electro-oxidation reaction was studied on carbon-supported Pt, Rh, and on Pt overlayers deposited on Rh nanoparticles. The synthesized electrocatalysts were characterized by TEM and XRD. The reaction products were monitored by on-line DEMS experiments. Potentiodynamic curves showed higher overall reaction rate for Pt/C when compared to that for Rh/C. However, on-line DEMS measurements revealed higher average current efficiencies for complete ethanol electro-oxidation to CO2 on Rh/C. The average current efficiencies for CO2 formation increased with temperature and with the decrease in the ethanol concentration. The total amount of CO2, on the other hand, was slightly affected by the temperature and ethanol concentration. Additionally, the CO2 signal was observed only in the positive-going scan, none being observed in the negative-going scan, evidencing that the C-C bond breaking occurs only at lower potentials. Thus, the formation of CO2 mainly resulted from oxidative removal of adsorbed CO and CHx,ad species generated at the lower potentials, instead of the electrochemical oxidation of bulk ethanol molecules. The acetaldehyde mass signal, however, was greatly favored after increasing the ethanol concentration from 0.01 to 0.1 mol L-1, on both electrocatalysts, indicating that it is the major reaction product. For the Pt/Rh/C-based electrocatalysts, the Faradaic current and the conversion efficiency for CO2 formation was increased by adjusting the amount of Pt on the surface of the Rh/C nanoparticles. The higher conversion efficiency for CO2 formation on the Pt1Rh/C material was ascribed to its faster and more extensive ethanol deprotonation on the Pt-Rh sites, producing adsorbed intermediates in which the C-C bond cleavage is facilitated. (C) 2012 Elsevier B.V. All rights reserved. (AU)

• Processo FAPESP: 08/05156-0 - Eletrocatálise de oxidação de etanol em monocamadas de platina depositadas em nanopartículas do tipo core-shell
• Beneficiário: Fabio Henrique Barros de Lima
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 09/11073-3 - Investigação do mecanismo de eletro-oxidação do etanol em nanopartículas metálicas.
• Beneficiário: Daniel Augusto Cantane
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 09/05545-0 - Eletrocatálise de oxidação de etanol em nanopartículas de ródio e platina-ródio: estudo do efeito da concentração de etanol e temperatura por espectrometria de massas on-line
• Beneficiário: Walter Felicori Ambrosio
• Modalidade de apoio: Bolsas no Brasil - Iniciação Científica