Support graphite nanofibers

Pt (5 wt%) supported on platelet and ribbon graphite nanofibers exhibited similar activities to those observed by Pt (25 wt°/o) on carbon black [138], This phenomenon was attributed to the crystallographic orientations adopted by the catalyst particles dispersed on graphitic nanofiber structures [139]. Also, the electrocatalysts supported on CNFs were less susceptible to CO poisoning than Pt supported on carbon black. 

Further novel observations are the hydroformylation of ethylene over graphite nanofiber-supported Rh catalysts,270 the transformation of a mixture of isomeric octenes to Cg-aldehydes,271 and the preparation of linear long-chain dialdehydes by the hydroformylation of linear a,co-dienes.272... 

The extraordinary mechanical, electTraiic and thermal properties of carbon nanofibers (CNFs) and carbon nanotubes (CNTs) make them suitable in several fields of materials technology, including supported catalysts for energy conversion. Graphite nanofibers, carbon filaments and carbon nanotubes, are terms employed to refer to nanofilamentous carbon. These materials can be classified into two categories fibers and tubes. A schematic representation of their structural features is shown in the Fig. 7.8. 

Previously, carbon black, carbon nanotubes, and graphite nanofibers have been explored as supports because of their large surface area and high electrical conductivity [225,226]. 

Park, C., Baker, R. (1998). Catalytic Behavior of Graphite Nanofiber Supported Nickel Particles 2. The Influence of the Nanofiber Structure. 

In the present article, the size and the loading efficiency of metal particles were investigated by changing the preparation method of carbon-supported platinum catalysts. First, the effect of acid/base treatment on carbon blacks supports on the preparation and electroactivity of platinum catalysts. Secondly, binary carbon-supported platinum (Pt) nanoparticles were prepared using two types of carbon materials such as carbon blacks (CBs) and graphite nanofibers (GNFs) to check the influence of carbon supports on the electroactivity of catalyst electrodes. Lastly, plasma treatment or oxyfluorination treatment effects of carbon supports on the nano structure as well as the electroactivity of the carbon supported platinum catalysts for DMFCs were studied. 

Graphitic nanofibers with herringbone structure (for description and preparation method see [279]) were also employed as supports for PtRu (1 1) [280]. The total metal eontent was 42 wt% and the catalyst particle size was 6 nm. DMFC polarization experiments showed an approximately 50% improvement in superficial current density at constant cell voltage for the supported vs. unsupported catalyst over the entire polarization curve [280]. 

Anderson PE, Rodriguez NM. Growth of graphite nanofibers from frie decomposition of CO/H2 over silica-supported iron-nickel particles. J Mater Res 1999 14 2912-21. 

Graphite Nanofibers as Support Materials for Fuel Cells... 

Graphite nanofibers (GNFs) have generated great interest as support materials due to their good graphitic structures and high electrical conductivity [6,24]. 

Avoiding carbon deposition on the catalyst is a major challenge [2, 3]. Carbon can be present as graphite-like coke and in the form of whiskers, or carbon nanofibers. The latter lead to detachment of the nickel crystallites from the support and breaking of the catalyst pellets. This may cause blockage of the reformer reactor tubes and the formation of hot spots. Higher hydrocarbons exhibit a larger tendency to form... 

Hsin Yu L, Hwang Kuo C, Yeh C-T (2007) Poly(vinylpyrrolidone)-modified graphite carbon nanofibers as promising supports for PtRu catalysts in direct methanol fuel cells. J Am Chem Soc 129 9999... 

Homogeneous deposition precipitation (HDP) is explored for the preparation of carbon nanofiber supported ruthenium catalysts. First, carbon nanofibers (CNF, 177 m /g) are oxidized using nitric acid thus activating the graphitic carbon surfiice. Second, ruthenium (hydr)oxide is deposited homogeneously onto the CNF by hydrolysis of urea at 363K. 

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