Nature of the bound states of molecular hydrogen in carbon nanohorns

TL;DR

This study investigates how molecular hydrogen behaves when confined within carbon nanohorns, revealing strong interactions and potential advantages for hydrogen storage compared to other carbon nanostructures.

Contribution

It provides detailed spectroscopic analysis of hydrogen in nanohorns, highlighting differences from bulk hydrogen and suggesting improved storage capabilities.

Findings

Presence of immobile hydrogen molecules in nanohorns

Narrower quasielastic line widths indicating restricted mobility

Strong interaction between hydrogen and nanohorn structures

Abstract

The effects of confining molecular hydrogen within carbon nanohorns are studied via high-resolution quasielastic and inelastic neutron spectroscopies. Both sets of data are remarkably different from those obtained in bulk samples in the liquid and crystalline states. At temperatures where bulk hydrogen is liquid, the spectra of the confined sample show an elastic component indicating a significant proportion of immobile molecules as well as distinctly narrower quasielastic line widths and a strong distortion of the line shape of the para - ortho rotational transition. The results show that hydrogen interacts far more strongly with such carbonous structures than it does to carbon nanotubes, suggesting that nanohorns and related nanostructures may offer significantly better prospects as lightweight media for hydrogen storage applications.