Molecular dynamics simulations for hydrogen adsorption in low energy collisions with carbon and boron-nitride nanotubes

Abstract

The capability of carbon nanotubes (CNTs) and boron-nitride nanotubes (BNNTs) to absorb hydrogen atoms might indicate if these materials can be used to develop an efficient and fast hydrogen nanosensor device. In this work, we carry out a theoretical study of the hydrogen adsorption mechanism by carbon and boron-nitride nanotubes irradiated by atomic hydrogen in the impact energy range of 0.25–100 eV. Hydrogen adsorption, reflection, and transmission probabilities are reported. The collision dynamics is calculated by performing quantum-classical molecular dynamics simulations within the self-consistent-charge density-functional tight-binding method. We include fitting curves for the angular distribution of reflected and transmitted H atoms by using a modified Yamamura formula. Results for CNTs follow a cosine-like law, while the majority of the projectiles tend to be scattered at angles lower than 60° for BNNTs. Based on previous studies for spherical and planar carbon-based configurations, we analyse the effect of the system’s curvature on the hydrogen adsorption on CNTs. We find that for collision energies below 5 eV, the scattering process depends on the carbon system curvature; meanwhile, the adsorption is independent for collision energies below 0.5 eV. Our results for the hydrogen adsorption rates for both types of nanotubes suggest that these materials can be used in hydrogen detector devices in a wide impact energy range.