Carbon Nanotube capillary filling

Modifications of the conduction properties of semiconducting carbon nanotubes by B (p-type) and N ( -type) substitutional doping has also been dis-cussed[3l] and, in addition, electronic modifications by filling the capillaries of the tubes have also been proposed[32]. Exohedral doping of the space between nanotubes in a tubule bundle could provide yet an-... 

The amount of hydrogen that can be stored on these tubes has been debated. One report shows that maximum storage capacity for a single-walled carbon nanotube (SWCNT) [7] and multiwalled carbon nanotubes [8] is approximately 8% by weight [9], Multiwalled carbon nanotubes are a collection of concentric single-walled nanotubes [10] versus the one-dimensional single-walled tubes [11], SWCNTs have very high surface-to-volume ratios as well as uniform pores, which allow for capillary action and thus the ability to be filled by condensation. 

The capillarity of carbon nanotubes offers two key properties, low chemical reactivity and superior burst strength. The hollow core of a carbon nanotube has been known to suck in water despite the hydrophobic nature of graphite, or molten metal such as lead [17] [52] and it has recently been filled, also by capillary forces, with molten silver nitrate [53]. Only nanotubes with a minimum capillary diameter of 4 nm were required, and found to be chemically less reactive than graphite. This property has been illustrated by monitoring the decomposition of silver nitrate within nanotubes in-situ in an electron microscope. In the nanospace available, chains of silver nanobeads were produced, separated by gas pockets developing gas pressures of up to 1300 bar at room temperature. 

Ajayan PM, lijima S, Capillary induced filling of carbon nanotubes. Nature, 361 333, 1993. 

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