Kinetics of 3He, 4He, H2, D2, Ne, and N2 sorption by bundles of single-walled carbon nanotubes. Quantum effects

Abstract

This is a study of the low temperature kinetics of the sorption and subsequent desorption of 3He, 4He, H2, D2, Ne, and N2 by bundles of single-wall carbon nanotubes with closed ends (c-SWNT). The characteristic times of the sorption and desorption processes are the same to within the experimental error. Annealing a sample of bundles at 500 °C greatly reduces the characteristic times and changes their temperature dependences. The effect of annealing decreased with increasing molecular weight of the dissolved gas. At temperatures below 16 K the sorption times for 3He, 4He, H2, and D2 depends weakly on temperature, which suggests a tunnel character of the sorption for these impurities by nanotube bundles. The effect of γ-irradiation of nanotube bundles on the sorption and desorption of hydrogen is qualitatively similar to the effect of annealing.

Absorption-desorption of carbon dioxide in carbon honeycombs at elevated temperatures

“…It was found in particular that the levels of gas absorption attain 4-6% in atomic count with respect to the number of carbon atoms in such substrates. This is about twice higher as compared with even theoretical values attainable in carbon nanotubes [16,17]. However, the carbon honeycomb structure was identified only when transmission electron microscopy and the exhaustive structural analysis were applied [14].…”

Absorption of atomic and molecular species in carbon cellular structures (Review article)

“…Such levels found for the above-mentioned gases are about twice higher as compared with even theoretical predictions for the closest pretender carbon single-wall nanotubes to serve for these purposes. Besides the application of nanotubes is questionable also because in practice it is difficult to open their ends and to provide access to their inner volumes [2,3].…”

“…Such light-weight carbon honeycombs are built of 2D graphene nanosheets and could be promising functional materials for many engineering applications. In particular, CHs structures were proven to allow storing high amounts of different gases surpassing the previous candidate, carbon nanotubes [2,3], by almost twice in storage capacity.…”

Nuclear Quantum Effects in the Layering and Diffusion of Hydrogen Isotopes in Carbon Nanotubes

“…Steric hindrance in narrow carbon nanopores caused by the higher excluded volume of H 2 was used to explain its slower self-diffusion (i.e., the Chudley–Elliott jump-diffusion mechanism), whereas D 2 was found to exhibit liquid-like self-diffusion . Similarly, the impact of nuclear quantum effects on diffusion of gases from single-carbon nanotubes has been studied experimentally, , revealing that H 2 diffuses out of the interior of carbon nanotubes at significantly faster rates than D 2 . Taken together, these works illustrate the importance of nuclear quantum effects in nanoconfined environments and motivates a more complete analysis of the range of phenomenology that may be observed in nanoconfined mixtures of H 2 and D 2 .…”

“…Recent progress in the synthesis of pure, structurally homogeneous, and relatively wide carbon nanotubes via the supergrowth (SG) method , has triggered new experimental studies of quantum molecular sieving of H 2 and D 2 at low temperatures . It was shown that single-component H 2 and D 2 adsorption isotherms have a steep uptake at low pressures, indicating formation of contact monolayer films on the concave inner surface of SG carbon nanotubes at 20 K .…”