Porosity, surface area, surface energy, and hydrogen adsorption in nanostructured carbons
Hydrogen adsorption isotherms at 77, 87, and 298 K have been measured on three samples of single-wall carbon nanotubes. The highest adsorption capacity (1.58 wt % at 77 K, 1.15 wt % at 87 K, and 0.02 wt % at 298 K) at atmospheric pressure has been observed in a chemically activated sample (activated with KOH), which has hybrid porosity between a carbon nanotube material and a microporous activated carbon. According to CO2 adsorption at 273 K and density functional theory pore size distributions from N2 adsorption, it is deduced that pores up to approximately 0.5−0.7 nm can adsorb hydrogen at ambient conditions. Isosteric heat of hydrogen adsorption has been calculated for the three samples, having initial values around 7−7.5 kJ mol-1. It is concluded that the hydrogen adsorption capacity of carbon nanotubes depends both on the extent of their surface area and on the adsorption energy of the surface sites.
| Main Authors: | , , , , , , |
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| Other Authors: | |
| Format: | artículo biblioteca |
| Language: | English |
| Published: |
American Chemical Society
2004
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| Online Access: | http://hdl.handle.net/10261/255236 http://dx.doi.org/10.13039/501100003339 http://dx.doi.org/10.13039/501100006280 |
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