Titanium-decorated Boron Nitride nanotube for Hydrogen Storage: A multiscale theoretical investigation
A multiscale Computational technique from available Quantum Mechanical and Molecular Dynamics (MD) code to user-subroutine computational fluid dynamics (CFD) files was applied to the H2 adsorption of Ti-decorated (10,0) single-walled BN nanotubes (BNNTs) with B-N defects. According to density functional theory (DFT), the Ti atom adsorbed in the defect protrudes outward from the surface and does not agglomerate. The Ti/BNNT possess an excellent affinity towards H2 molecules with thermodynamically favorable binding energies. Up to seven H2 can partially attach near the Ti in quasi-molecular form due to the cationic functionalized Ti and heteropolar B-N bonds at the surface. The MD simulation further reveals that the seven H2 are indeed physisorbed in two distinct regions near to (at ~2 Å) and far from (at ~4 Å) the Ti atom. The thermal properties obtained from MD was utilized in the CFD code to quantify the thermal energy transfer. According to CFD, the equilibrium pressure distribution for a type III H2 cylinder is initially low within its locality. The rate of change of pressure increase is quite steep as it rises due to a sudden increase in temperature upon uptake and it eventually slows down when the local temperature reaches its saturation value.