Carbon nanotubes capacity

Hollow carbon nanotubes (CNTs) can be used to generate nearly onedimensional nanostrutures by filling the inner cavity with selected materials. Capillarity forces can be used to introduce liquids into the nanometric systems. Here, we describe experimental studies of capillarity filling in CNTs using metal salts and oxides. The filling process involves, first a CNT-opening steps by oxidation secondly the tubes are immersed into different molten substance. The capillarity-introduced materials are subsequently transformed into metals or oxides by a thermal treatment. In particular, we have observed a size dependence of capillarity forces in CNTs. The described experiments show the present capacities and potentialities of filled CNTs for fabrication of novel nanostructured materials. 

It should he mentioned that carbon nanotubes do not store more than 0.5 wt. % H2 at room temperature, although it was claimed earlier that much higher capacities can be obtained. The initial results of carbon nanotubes with 30-60 wt.% of stored hydrogen are now considered to have been an experimental error. 

Hepplestone SP, Ciavarella AM, Janke C, Srivastava GP (2006) Size and temperature dependence of the specific heat capacity of carbon nanotubes. Surface Science 600 3633-3636. 

Another technology being pursued in the search for high-capacity hydrogen storage media is that of carbon nanotubes. Since their discovery in 1991 by Sumio... 

Although a lot of research has been reported on the use of various carbonaceous materials in defluoridation, no known column or full-scale plant operation is easily available in open literature. One reason for this is that most carbonaceous materials show poor adsorption capacity (Table 4) for fluoride and therefore only laboratory-scale performances have so far been reported. Amorphous alumina supported on carbon nanotubes on the other hand show high capacity (28.7 mgF/g adsorbent) for fluoride and is therefore a promising material for drinking water defluoridation. 

Hydrogen storage in carbon has been considered during the last few years on account of the existence of new carbon nanomaterials, such as fullerenes, superactivated carbons, carbon monoliths, carbon nanotubes, and carbon nanohoms [147,166,176-179], distinguished by their high adsorption capacities, hydrophobic nature, and high adsorption/desorption rates [170],... 

In other similar structures, such as IRMOF-6 and IRMOF-8, the specific hydrogen uptake is approximately doubled and quadrupled, respectively, compared to MOF-5 at room temperature and 2.0MPa pressure [244], The hydrogen absorption capacity of these structures at room temperature is comparable to that of carbon nanotubes at cryogenic temperatures and can be fine-tuned by modifying the porosity of the structure with suitable linkers [244],... 

Tibbets, G.G., Meisner, G.P. and Oik, Ch.H. (2001) Hydrogen storage capacity of carbon nanotubes, filamenta, and vapor-grown libers, Carbon 39, 2291-2301. 

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