Sealing off a carbon nanotube with a self-assembled aqueous valve for the storage of hydrogen in GPa pressure

TL;DR

This paper proposes a novel method using self-assembled aqueous valves at the ends of carbon nanotubes to store hydrogen at GPa pressures, offering a recyclable, high-density, and non-destructive storage solution.

Contribution

It introduces a new hydrogen storage technique utilizing self-assembled water-based valves to seal nanotubes under high pressure, demonstrated through molecular dynamics simulations.

Findings

Aqueous valves can be formed around nanotube ends with hydrophilic groups.

Valves can withstand GPa pressures and allow hydrogen containment.

Hydrogen release is achievable by melting the aqueous valve.

Abstract

The end section of a carbon nanotube, cut by acid treatment, contains hydrophillic oxygen groups. Water molecules can self-assemble around these groups to seal off a carbon nanotube and form an "aqueous valve". Molecular dynamics simulations on single-wall (12,12) and (15,15) tubes with dangling carboxyl groups show that the formation of aqueous valves can be achieved both in the absence of and in the presence of high pressure hydrogen. Furthermore, significant diffusion barriers through aqueous valves are identified. It indicates that such valves could hold hydrogen inside the tube with GPa pressure. Releasing hydrogen is easily achieved by melting the "aqueous valve". Such a design provides a recyclable and non- destructive way to store hydrogen in GPa pressure. Under the storage conditions dictated by sealing off the container in liquid water, the hydrogen density inside the container is higher than that for solid hydrogen, which promises excellent weight storage efficiency.