Carbon–CeO2 composite nanofibers as a promising support for a PtRu anode catalyst in a direct methanol fuel cell (original) (raw)
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In this study, Co/CeO 2 decorated carbon nanofibers are introduced as effective electro-catalyst for methanol oxidation. Poly(vinyl alcohol) was used as carbon source due to its high carbon content characteristic as compared to many others polymer precursors for CNFs synthesis. Preparation of the introduced nanofibers could be achieved by calcination of electrospun nanofibers composed of cerium (III) acetate hydrate, cobalt (II) acetate tetra hydrate and poly(vinyl alcohol) in nitrogen environment at 700 1C. The produced sintered powder was characterized by X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM), field-emission scanning electron microscopy (FESEM) equipped with rapid EDX (energy dispersive analysis of X-ray). The invoked characterization techniques indicated that the obtained material is carbon nanofibers decorated by Co/CeO 2 nanoparticles. Investigation of the electrocatalytic activity of the introduced decorated nanofibers toward methanol oxidation indicated good performance as the corresponding current density increased with increasing methanol content in the alkaline medium. Interestingly, the introduced catalyst revealed negative onset potential ( À50 mV vs. Ag/AgCl) which is a superior value among the reported non-precious electrocatalyst. Moreover, methanol oxidation takes place at relatively low applied voltage (180 mV vs. Ag/AgCl) which adds additional advantage for the introduced material. Overall, the introduced study opens new avenue for cheap and effective transition and rare earth family-based nanomaterials as non-precious catalyst for fuel cell application.
CO tolerant PtRu–MoOx nanoparticles supported on carbon nanofibers for direct methanol fuel cells
Journal of Power Sources, 2009
Novel nanostructured catalysts based on PtRu-MoO x nanoparticles supported on carbon nanofibers have been investigated for CO and methanol electrooxidation. Carbon nanofibers are prepared by thermocatalytic decomposition of methane (NF), and functionalized with HNO 3 (NF.F). Electrocatalysts are obtained using a two-step procedure: (1) Pt and Ru are incorporated on the carbon substrates (Vulcan XC 72R, NF and NF.F), and (2) Mo is loaded on the PtRu/C samples. Differential electrochemical mass spectrometry (DEMS) analyses establish that the incorporation of Mo increases significantly the CO tolerance than respective binary counterparts. The nature of the carbon support affects considerably the stabilization of MoO x nanoparticles and also the performance in methanol electrooxidation. Accordingly, a significant increase of methanol oxidation is obtained in PtRu-MoO x nanoparticles supported on non-functionalized carbon nanofiber, in parallel with a large reduction of the Pt amount in comparison with binary counterparts and commercial catalyst.
International journal of electrochemical science
Carbon nanofibers (CNFs) web supported platinium nanoparticles were prepared by an electrochemical deposition method at sweep times of 5, 10, 20 and 40. Structure, composition and surface morphology of Pt incorporated CNF were analyzed by using X-ray diffraction (XRD), Energy dispersive x-ray spectroscopy (EDX), Field emission scanning electron microscopy (FE-SEM) and High resolution transmission electron microscopy (HR-TEM) techniques. Structural analysis by XRD showed face centered cubic crystal structure of Pt. Particle size and loading level (wt%) of Pt were found to increase from 10.7 to 18.6 nm and 3.3 to 7.0 6%, respectively with the increase of sweep times. SEM images showed that the Pt nano particles were agglomerated and effectively adhered on CNF with increase of sweep times. Nanocrystalline Pt and its FCC structure were also confirmed by using HR-TEM. Electrocatalytic activity of the nano Pt/CNF composite was demonstrated by linear voltammetrty, cyclic voltammetry and im...
Electrocatalysts for Methanol Oxidation Based on Platinum/Carbon Nanofibers Nanocomposite
Journal of Nanoscience and Nanotechnology, 2011
New carbon nanomaterials, i.e., carbon nanotubes and nanofibers, with special physico-chemical properties, are recently studied as support for methanol oxidation reaction electrocatalysts replacing the most widely used carbon black. Particularly, carbon fibrous structures with high surface area and available open edges are thought to be promising. Platelet type carbon nanofibers, which have the graphene layers oriented perpendicularly to the fiber axis, exhibit a high ratio of edge to basal atoms. Different types of carbon nanofibers (tubular and platelet) were grown by plasma enhanced chemical vapour deposition on carbon paper substrates. The process was controlled and optimised in term of growth pressure and temperature. Carbon nanofibers were characterised by high resolution scanning electron microscopy and X-ray photoelectron spectroscopy to assess the morphological properties. Then carbon nanofibers of both morphologies were used as substrates for Pt electrodeposition. High resolution scanning electron microscopy images showed that the Pt nanoparticles distribution was well controlled and the particles size went down to few nanometers. Pt/carbon nanofibers nanocomposites were tested as electrocatalysts for methanol oxidation reaction. Cyclic voltammetry in H 2 SO 4 revealed a catalyst with a high surface area. Cyclic voltammetry in presence of methanol indicated a high electrochemical activity for methanol oxidation reaction and a good long time stability compared to a carbon black supported Pt catalyst.
Fuel cell performance of Pt electrocatalysts supported on carbon nanocoils
International Journal of Hydrogen Energy, 2014
Polymer electrolyte membrane fuel cell Carbon nanocoils Electrocatalyst a b s t r a c t Carbon nanocoils (CNCs) synthesized via the catalytic graphitization of resorcinolformaldehyde gel were investigated as an electrocatalyst support in PEMFC anodes. Their textural and physical properties make them a highly efficient catalyst support for anodic hydrogen oxidation in low temperature PEMFC.
Electrochimica Acta, 2013
Different carbon materials with high electrical conductivity have been studied as electrocatalyst support for direct alcohol fuel cells (DAFCs). The aim of the work was to establish the influence of the support on the catalyst properties and to improve their efficiency in the fuel cell. Carbon nanofibers (CNFs), carbon nanocoils (CNCs) and ordered mesoporous carbons (gCMK-3) have been used for synthesizing platinum catalysts by the polyol method. Results have been compared with those obtained for a platinum catalyst supported on Vulcan XC-72R, prepared by the same method, and for the commercial Pt/C catalyst from E-TEK. It has been demonstrated that novel carbon supports could help to oxidize CO adsorbed on platinum particles more easily than the commercial carbon support and improve the alcohol oxidation reaction, both in terms of onset potential and current density. The catalyst supported on gCMK-3 carbon resulted to be the most effective in both the methanol and ethanol oxidation, which can be attributed to its ordered structure and high electrical conductivity.
Applied Catalysis B Environmental
Pt–Ru catalysts supported on carbon nanofibers were synthesized by different synthesis methods: reduction with sodium borohydride, methanol and formate ions (denoted as BM, MeOH and SFM, respectively). The catalyst synthesized by the SFM route was heat-treated (denoted as SFM TT) in order to enhance its catalytic activity, generating in this way a new catalyst. Physical characterization was performed by means of energy-dispersive X-ray (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). Results showed that Pt–Ru/CNF catalysts with similar metal content (20 wt%) and atomic ratio (Pt:Ru 1:1) can be obtained by all methodologies. In order to determine the CO tolerance and the electroactive areas of the materials, adsorbed CO stripping experiments were performed. CO stripping curves were modified with the addition of Ru that shifts the onset and peak electrooxidation potentials to more negative values compared with those obt...
Structural designing of Pt-CeO 2/CNTs for methanol electro-oxidation
Journal of Power Sources, 2007
In an attempt to utilize CeO 2 as a co-catalyst with Pt for methanol electro-oxidation, Pt-CeO 2 /CNTs were prepared through structural designing by adsorbing Pt nanoparticles on CeO 2 coated CNTs. X-ray Diffraction (XRD), energy dispersive X-ray spectroscopy (EDX) were used to analyze the composition of the prepared catalysts. Zeta potential analysis, high resolution transmission electron microscopy (HRTEM) and cyclic voltammetry (CV) methods indicated that Pt nanoparticles are selectively adsorbed on CNTs other than CeO 2 surface. Pt-CeO 2 /CNTs were compared with Pt supported on CNTs in terms of electrochemical active surface (EAS) areas, methanol electro-oxidation activity, and chronoamperometry, results indicating that CeO 2 can enhance the catalytic activity of Pt for methanol electro-oxidation with no apparent decrease of EAS. The CO stripping test showed that CeO 2 can make CO stripped at a lower potential, which is helpful for CO and methanol electro-oxidation.
Enhanced methanol electro-oxidation activity of PtRu catalysts supported on heteroatom-doped carbon
Electrochimica Acta, 2008
PtRu nanoparticles deposited on a carbon black substrate are catalysts commonly employed for the electrooxidation of methanol and carbon monoxide-containing hydrogen feeds [1,. However, improvement of effective electrocatalysts is an essential goal in the development of a practical DMFC. The use of carbon black as a support for noble metals is frequent in the electrodes of polymer membrane electrolyte fuel cells, but the impact of the chemical and physical properties of the carbon on electrocatalytic performance are not yet sufficiently understood. The presence of oxygen surface groups influences the surface behaviour of carbons to a considerable extent . As examples, the wettability and adsorptive behaviour of a carbon, as well as its catalytic and electrical properties, are influenced by the nature and extent of such surface groups. The varying role of oxygenated functionalities on the formation of the dispersed platinum has been established [5-8], but not with an additional metal such as ruthenium. In the present investigation we report how the performance in methanol electrooxidation of PtRu nanoparticles deposited on a carbon black substrate, previously functionalized with oxygen surface groups, is improved.