Excitation spectrum of hydrogen adsorbed to carbon nanotubes

TL;DR

This study investigates the microscopic dynamics and storage capacity of hydrogen adsorbed on carbon nanotubes using inelastic neutron scattering, revealing high storage potential and controlled release properties.

Contribution

It provides new insights into hydrogen adsorption layers and excitation spectra on carbon nanotubes, demonstrating enhanced storage and release mechanisms.

Findings

Higher storage capacities in chemically treated nanotubes

Hydrogen remains stable below 150 K and can be released above 200 K

Excitation spectrum changes during hydrogen desorption

Abstract

We have studied the microscopic dynamics of hydrogen adsorbed to bundles of single walled carbon nanotubes using inelastic neutron scattering. Evidence is obtained for much higher storage capacities in chemically treated compared to as prepared material. This indicates an additional adsorption layer inside the tubes. Well pronounced excitations in the H2 spectrum at low energies confirm this conclusion. The desorption of hydrogen is monitored in real time as a function of temperature. Hydrogen storage is highly stable below 150 K in agreement with the harmonic evolution of the hydrogen spectrum, which indicates a strong binding potential. Above 200 K hydrogen can be released in a controlled way by simple heating. The excitation spectrum changes significantly during the release. Remnants of hydrogen persist up to 400 K.