Polycrystalline carbon nanotubes for hydrogen storage using molecular dynamics simulations

Abstract

Hydrogen storage and Adsorption hydrogen energy in both Pristine and Polycrystalline single-walled carbon nanotubes has been studied using molecular dynamics simulations (MDS). Research interest in hydrogen because of its pollution-free, abundance and high energy content in unit mass compare to other fuel. Hydrogen is an appropriate alternative in terms of green energy technologies for the carbon-based fossil fuels technologies. Hydrogen can be stored in solid adsorbent in terms of physisorption of hydrogen gas molecules in a safe and energy efficient manner. The interaction between Carbon nanotubes (CNT) and hydrogen molecules, and interatomic interactions of the CNT are modeled via Lennard-Jones (LJ) potential using Tersoff potentials. Adsorption hydrogen energy and hydrogen gravimetric storage capacity are evaluated by the effects of various pressure and temperature using Potential energy distributions (PED). Adsorption hydrogen capacity are evaluated at different temperature i.e. 77 K, 100 K, 200 K, 273 K and up to 40 bar pressure starting from 1 bar for both Pristine and Polycrystalline single-walled carbon nanotubes. At 77 K and 20bar, the hydrogen gravimetric storage capacity of 6.2144% for pristine and 6.3133% for polycrystalline CNT and Adsorption hydrogen energy of -0.021ev for pristine and -0.0206ev for polycrystalline CNT is observed. As the results obtained we observed that the decreasing in temperature and increasing in pressure, gravimetric density (GD) for hydrogen storage is increased for Pristine as well as Polycrystalline single-walled carbon nanotubes. Gravimetric density for hydrogen storage with the effect of grain boundaries in CNT i.e. Polycrystalline CNT is higher than Pristine CNT at different temperature and Pressure. The gravimetric density for hydrogen storage and adsorption hydrogen energy with the effect of different strain and defects is applied in both the Pristine CNT and polycrystalline CNT is evaluated.