Structural analysis of PdRh/C and PdSn/C and its use as electrocatalysts for ethanol oxidation in alkaline medium

Sem informaçãoThe Pd/C, PdRh(50:50)/C and PdSn(50:50)/C nanomaterials were used as electrocatalysts for ethanol (EtOH) oxidation in Direct Ethanol Fuel Cell (DEFC) in an alkaline medium. This work aims to provide a complete physical characterization of the nanomaterials, elucidate the bifunctional mechanism concerning ethanol oxidation reaction and understand the influence of carbon - metal bonding in the electrochemical activity. These nanomaterials were investigated by X-ray photoelectron spectroscopy (XPS) and revealed that the atomic percentage of the surface is different of those obtained by Energy Dispersive X-ray spectroscopy (EDS). Raman spectroscopy showed a bonding between palladium and carbon atoms which can play a decisive role in the performance of the materials. Attenuated Total Reflectance technique coupled to the Fourier Transform Infrared spectroscopy (ATR-FTIR) made possible to investigate the oxidation products originated by the ethanol oxidation, and all the electrocatalysts showed the presence of acetaldehyde, carbonate ions, acetate and carbon dioxide, suggesting that the mechanism of oxidation is incomplete. Among all the nanomaterials studied, PdSn(50:50)/C showed the best electrochemical and Fuel Cell's results. It is about 33% better than Pd/C. The micrographs obtained by Transmission Electron Microscopy (TEM) revealed some agglomerate regions, but they are consistent with the literature data. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.442937951Sem informaçãoSem informaçãoSem informaçã

Development of new systems of nano-disperse Pt-(2%Pt-Ce0.9W0.1O2)/C electrocatalysts tolerant to carbon monoxide (CO) for PEMFC anodes

The nanophase material (powder) of Ce0.9W0.1O2 was synthesized via coprecipitation of oxalates of cerium (IV) and tungsten cations. Pt-Ce0.9W0.1O2 (2 wt% Pt) was prepared by an alcohol-reduction process using H2PtCl6.6H2O as source of Pt, Ce0.9W0.1O2 as support and ethylene glycol as solvent and reducing agent. Pt-Ce0.9W0.1O2 was physically mixed with commercial Pt/C E-TEK (20 w% Pt) to produce the Pt-(2%Pt-Ce0.9W0.1O2)/C electrocatalyst. The prepared electrocatalysts were characterized by energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and CO stripping. The performances of Pt/C E-TEK and Pt-(2%Pt-Ce0.9W0.1O2)/C electrocatalysts were tested in single fuel cell fed with a mixture H2/CO (100 ppm of CO). The results showed that the mixture of 2%Pt-Ce0.9W0.1O2 and Pt/C E-TEK increases the CO tolerance in a single fuel cell operating at 85 ºC compared with Pt/C E-TEK

Development Of New Systems Of Nano-disperse Pt-(2%pt-ce0.9w 0.1o2)/c Electrocatalysts Tolerant To Carbon Monoxide (co) For Pemfc Anodes

The nanophase material (powder) of Ce0.9W0.1O 2 was synthesized via coprecipitation of oxalates of cerium (IV) and tungsten cations. Pt-Ce0.9W0.1O2 (2 wt% Pt) was prepared by an alcohol-reduction process using H2PtCl 6.6H2O as source of Pt, Ce0.9W 0.1O2 as support and ethylene glycol as solvent and reducing agent. Pt-Ce0.9W0.1O2 was physically mixed with commercial Pt/C E-TEK (20 w% Pt) to produce the Pt-(2%Pt-Ce 0.9W0.1O2)/C electrocatalyst. The prepared electrocatalysts were characterized by energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and CO stripping. The performances of Pt/C E-TEK and Pt-(2%Pt-Ce0.9W0.1O2)/C electrocatalysts were tested in single fuel cell fed with a mixture H2/CO (100 ppm of CO). The results showed that the mixture of 2%Pt-Ce0.9W 0.1O2 and Pt/C E-TEK increases the CO tolerance in a single fuel cell operating at 85°C compared with Pt/C E-TEK. ©The Electrochemical Society.431185189Du Melle, F., The global and urban environment: The need for clean power systems (1998) Journal of Power Sources, 71 (1-2), pp. 7-11Oliveira Neto, A., Farias, A.L., Dias, R.R., Brandalise, M., Linardi, M., Spinacé, E.V., Enhanced electro-oxidation of ethanol using PtSn/CeO2-C electrocatalyst prepared by an alcohol-reduction process (2008) Electrochemistry Communications, 10 (9), pp. 1315-1317Pamqvist, A.E.C., Wirde, M., Gelius, U., Muhammed, M., Surfaces of Doped Nanophase Cerium Oxide Catalysts (1999) NanoStructured Materials, 11 (8), pp. 995-1007Rothenberg, G., De Graaf, E.A., Bliek, A., Solvent-Free Synthesis of Rechargeable Solid Oxygen Reservoirs for Clean Hydrogen Oxidation (2003) Angew. Chem. Int. Ed., (42), pp. 3366-3368. , BartGu, D.M., Chu, Y.Y., Wang, Z.B., Jiang, Z.Z., Yin, G.P., Liu, Y., Methanol oxidation on Pt/CeO2-C electrocatalyst prepared by microwave-assisted ethylene glycol process (2010) Applied Catalysis B: Environmental, 102 (1-2), pp. 9-18Hou, Z., Yi, B., Lin, Z., Zhang, H., CO tolerance of PtRu-HxMeO3/C (Me = W, Mo) made by composite support method (2003) Journal of Power Sources, 123 (2), pp. 116-125Santiago, E.I., Batista, M.S., Assaf, M.E., Ticianelli, E.A., Mechanism of CO tolerance on Molybdenum-Based Electrocatalysts for PEMFC (2004) Journal of the Electrochemical Society, 151 (7), pp. A944-A94