Investigation of chemical and adsorption properties of carbon nanotubes: building a bridge for technological applications of carbon nanotubes.

摘要

In the present work, the results of investigations of the chemical, adsorption and optical properties of carbon nanotubes (CNTs) will be presented. A brief introduction describes CNTs, how they are produced, and how they are purified. Experimental investigations of the effect of air/HCl purification on the introduction of oxygen functionalities will be reported. It was established that air/HCl purification results in the introduction of oxygen containing functionalities to single wall carbon nanotubes (SWCNTs) produced by the HiPco (high pressure carbon monoxide) method. The introduced oxygen functionalities decompose at ~670 K detected as masses 18 (H2O), 28 (CO) and 44 amu (CO2) in the mass spectrum. The exact chemical nature of those functionalities requires more detailed investigation.Low-temperature (100 K) adsorption of acetone on carbon black, as-produced and air/HCl purified SWCNTs allowed the accessibility of different adsorption sites in SWCNTs to be established. A key variable was the vacuum-annealing temperature. The energetics of interaction of acetone with different adsorption sites was determined. The most energetic adsorption sites were found to be endohedral adsorption sites.The interaction of solvents with carbonaceous materials was studied under different conditions: sonication, reflux, and exposure to solvent vapors over a range of pressures. It was shown that the binding energy of molecules with SWCNTs depends on the interaction conditions: the higher the temperature and pressure during the contact of molecules with SWCNTs, the higher the adsorption energy of molecules on/in SWCNTs. This finding suggests a "pressure gap" effect for nanoporous carbonaceous materials.Infrared studies of CNTs suggest that molecules adsorbed inside of endohedral channels are invisible to IR. This result is in contrast with experimental findings by other authors. Additional research, both experimental and theoretical, must be done to identify factors responsible for the screening of molecules adsorbed inside SWCNTs.