Faradaic efficiency of ethanol oxidation to CO2 at metallic nanoparticle/short-side-chain PFSA solid-state electrolyte interfaces investigated by on-line DEMS

Autor(es)

Silva, W. O. ^[1] ; Queiroz, A. C. ^[1] ; Paganin, V. A. ^[1] ; Lima, F. H. B. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Chem Sao Carlos, Ave Trab Sao Carlense 400, CP 780, BR-13560970 Sao Carlos, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: JOURNAL OF ELECTROANALYTICAL CHEMISTRY; v. 824, p. 99-107, SEP 1 2018.
• Citações Web of Science: 2

Resumo

Ethanol has attracted attention as a renewable fuel for application in electrochemical reformers, for the production of hydrogen, and in fuel cells. The electro-oxidation of ethanol, however, faces a central drawback related to the difficulty for the C-C bond cleavage, which is required for its complete electro-oxidation to CO2. Thus, the efficiency has to be increased and this is the main challenge for the use of ethanol as a fuel in such devices. In this study, the ethanol electro-oxidation was studied at metallic nanoparticle/Aquivion (R) solid-state interfaces. The nanostructured electrocatalysts were formed by Pt/C, Rh/C, Sn/Pt/C, and Sn/(PtRh)/C nanoparticles, and the electrocatalysis was tested at temperatures ranging from 25 to 140 degrees C. Potentiostatic and potentiodynamic measurements showed a marked effect of the temperature on the electrocatalytic activity and, principally, on the stability, due to lower poisoning by adsorbed reaction intermediates above 100 degrees C. By using a new setup for coupling the solid-state electrolyte cell with a DEMS (Differential Electrochemical Mass Spectrometry) equipment, with a proper calibration, it was possible to determinate the faradaic efficiency of ethanol electrochemical oxidation to CO2 at each studied condition. The results showed that the CO2 current efficiencies (CCE) increased from approximately zero, at 25 degrees C, to 54.0, 44.1, 22.7, and 13.1% for Rh/C, Pt/C, Sn/(PtRh)/C (1:3), and Sn/Pt/C (1:3), respectively, at 120 degrees C, under potentiostatic conditions. The impact of the temperature was more prominent for Rh/C, and this was associated to its ability for ethanol dehydrogenation in the methyl group, resulting in the formation of adsorbed oxametallacycle species, that facilitates the direct cleavage of the C-C bond, this step being more rapid at 120 degrees C than at ambient temperature. (AU)

• Processo FAPESP: 12/17581-3 - Oxidação Eletroquímica do Etanol em Células a Combustível de Eletrólito Polimérico: Estudo Quantitativo das Vias Reacionais por Espectrometria de Massas On-line.
• Beneficiário: Adriana Coêlho Queiroz
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 13/16930-7 - Eletrocatálise V: processos eletrocatalíticos de interconversão entre as energias química e elétrica
• Beneficiário: Edson Antonio Ticianelli
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 16/13323-0 - Eletroquímica do Dióxido de Carbono e da Água: Aplicação em Estocagem e Aproveitamento de Energia
• Beneficiário: Fabio Henrique Barros de Lima
• Modalidade de apoio: Auxílio à Pesquisa - Regular