Open single-walled carbon nanotubes (SWNTs) are attractive as potential storage media for gases, liquids, solids and biological molecules. In the area of gas storage, there exits many controversies as to the real storage capacity of SWNT. In order to shed light into these controversies and understand how the storage capacity is affected by chemical modifications, we investigated the micropore structure of various SWNTs samples by nitrogen and argon adsorption technique at low pressures. Much effort was placed in the establishment of protocol for obtaining meaningful isotherms. The conditions to obtain reliable isotherms will be presented discussed and illustrated with various examples. The proportion of open SWNT is estimated from these isotherms with the methods. We will show how the pore size distribution is dependent on the model used. We will demonstrate through series of measurements with various characterizations methods the way to derive meaningful pore size distributions. In addition, we will show how chemical modifications with various methods and reagents affect the pore volumes. The results provide new insights into the controversies surrounding gas storage in SWNT. In light of these results, a proper, reproducible and reliable protocol for the preparation of SWNT for gas uptake should be described.
Steacie Institute for Molecular Sciences, National Research Council of Canada
100 Sussex Drive, Ottawa, ON K4A 3H9 CANADA
Phone: 613-990-0977 Fax: 613-991-2648