Platinum nanoparticles embledded in layer-by-layer films from SnO2/polyallylamine for ethanol electrooxidation

Autor(es)

Barretto, Caroline B. ^[1] ; Parreira, Renato L. T. ^[1] ; Goncalves, Rogria R. ^[1] ; de Azevedo, Dayse C. ^[2] ; Huguenin, Fritz ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Fac Filosofia Ciencias & Letras Ribeirao Preto, Dept Quim, BR-14040901 Ribeirao Preto, SP - Brazil

^[2] NovoCell Energy Syst SA, BR-13478722 Americana, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Journal of Power Sources; v. 185, n. 1, p. 6-12, OCT 15 2008.
• Citações Web of Science: 5

Resumo

Self-assembled films from SnO2 and polyallylamine (PAH) were deposited on gold via ionic attraction by the layer-by-layer(LbL) method. The modified electrodes were immersed into a H2PtCl6 solution, a current of 100 mu A was applied, and different electrodeposition times were used. The SnO2/PAH layers served as templates to yield metallic platinum with different particle sizes. The scanning tunnel microscopy images show that the particle size increases as a function of electrodeposition time. The potentiodynamic profile of the electrodes changes as a function of the electrodeposition time in 0.5 mol L-1 H2SO4, at a sweeping rate of 50mVs(-1). Oxygen-like species are formed at less positive potentials for the Pt-SnO2/PAH film in the case of the smallest platinum particles. Electrochemical impedance spectroscopy measurements in acid medium at 0.7 V show that the charge transfer resistance normalized by the exposed platinum area is 750 times greater for platinum electrode (300 k Omega cm(2)) compared with the Pt-SnO2/PAH film with 1 min of electrodeposition (0.4 k Omega cm(2)). According to the Langmuir-Hinshelwood bifunctional mechanism, the high degree of coverage with oxygen-like species on the platinum nanoparticles is responsible for the electrocatalytic activity of the Pt-SnO2/PAH concerning ethanol electrooxidation. With these features, this Pt-SnO2/PAH film may be grown on a proton exchange membrane (PEM) in direct ethanol fuel cells (DEFC). (c) 2008 Elsevier B.V. All rights reserved. (AU)

• Processo FAPESP: 06/06035-7 - Utilização de nanocompósitos para armazenamento e conversão de energia: um estudo teórico-experimental
• Beneficiário: Renato Luis Tame Parreira
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 05/00106-7 - Materiais eletroativos automontados
• Beneficiário: Fritz Cavalcante Huguenin
• Modalidade de apoio: Auxílio à Pesquisa - Regular