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Open Access item Estructura y propiedades de las nanofibras de carbono. Aplicación como soporte de electrocatalizadores

Authors:Sebastián del Río, David
Keywords:Nanofibras de carbono, Catalizadores, Pilas de combustible, Electrocatalizador
Issue Date:24-Jun-2011
Publisher:CSIC - Instituto de Carboquímica (ICB)
Abstract:Carbon nanofiber (CNF) are a synthetic graphite-like nanostructured carbon material,with advantageous properties for several application fields such as catalysis or composites. CNF can be produced by means of catalytic decomposition of a carbon containing gas (such as methane or ethylene) over transition metals (like nickel, cobalt or iron).
This work deals with the study of the influence of some synthesis conditions,i.e. temperature, gas composition and space velocity, on the nanofilaments morphology, their crystalline structure, ordering degree, porosity and electronic conductivity, which enables favoring either a certain group of properties or the other (e.g. porosity or crystallinity), but not all of them jointly).
Carbon nanofiber treatments have been carried out with the aim of increasing the amount of surface oxygen groups or of developing a higher specific surface area. The functionalization with strong acids is effective to generate oxygen surface groups that, under certain conditions, can be useful in practical purposes. However, chemical activation of CNF does not entail significant advantages regarding the development of porosity.
Subsequently, the study focuses on the use of CNF as electrocatalyst support for fuel cells. These kinds of devices directly and efficiently convert the chemical energy of a fuel to electrical energy, which has caused an increasing interest in research and developments. The electrocatalysts, based on platinum supported on carbon, are responsible of this energy conversion electrochemical process.
The use of nanofibers as electrocatalytic support is advantageous in several aspects, improving the diffusion of reactants and products, contributing to the increase of the electronic conductivity and enhancing the metal-support interaction. In this work, the effect of CNF as support for Pt and PtRu on the electrocatalytic activity has been investigated. The support properties seriously determine the catalyst activity, finding that a compromise between the carbon ordering degree and the porous structure is necessary. Besides, the functionalization of CNF allows a slight increase in the activity. Finally, the CNF.supported catalysts have been submited to accelerated corrosion processes, concluding that CNF properties also influence the catalyst resistance to degradation.
URI:http://hdl.handle.net/10261/37707
Appears in Collections:(ICB) Tesis

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