Tight-binding simulations of hydrogen storage in carbon nanotube-based materials

Abstract

This study investigates the molecular-level behavior and performance of carbon nanotube-based hydrogen storage systems using tight-binding simulations. Dynamic analysis of the effects of nanotube radius and metal additives revealed that while the absolute number of molecules adsorbed increases with increasing radius, the weight-based storage capacity ultimately decreases because the increase in the mass of the nanotube itself dominates. Conversely, doping titanium and lithium nanoparticles significantly enhances storage capacity through strong metal‑hydrogen interactions such as chemisorption and Kubas interaction. Specifically, doping with titanium nanoparticles promotes hydrogen storage on the CNT surface, resulting in enhanced reversible hydrogen storage capacity compared to other metal additives. Analysis results confirmed a critical point of initial hydrogen density of 0.015 g/cc, below which storage performance deteriorates rapidly due to kinetic energy imbalance. With effective storage capacities approximately up to 3.72 wt%, these findings offer essential foundational data for optimizing the design of high-efficiency hydrogen storage materials.