Study of hydrogen storage behaviour in phosphorus-doped carbon nanotube using DFTB method

By using the density functional based tight binding (DFTB) method, we study the hydrogen storage performance of P-doped carbon nanotube with different diameters which contain 108,120 and 132 carbon atoms respectively. The hydrogen storage capacity of these p-doped carbon nanotubes range from 2.8 wt% to 7.8 wt%. The average binding energy between hydrogen and P-doped carbon nanotube ranges from 0.82eV to 0.14eV, and the binding energy( E b ( H 2 )) inside the nanotube is about 3 times that outside the nanotube . Up to 9 carbon atoms can be adsorbed around the phosphorus atom under 100 K. After phosphorus atoms are incorporated, carbon atoms exhibit electronegativity or electronpositive, which enhances their ability to bind to hydrogen. The P-doped carbon nanotube has relatively high desorption temperature, which can reach up to 450k. Because it can adsorb hydrogen molecules at relatively higher temperatures, phosphorus-doped carbon nanotubes can be used as an effective carrier for transporting hydrogen in production. • The binding energy between hydrogen and carbon nanotube of P-doped carbon nanotube is relatively high. • P-doped carbon nanotube can adsorb hydrogen stably. • The desorption temperature of P-doped carbon nanotube is relatively high which is above 450K. • Phosphorus-doped carbon nanotube an effective carrier for transporting hydrogen in production. • Phosphorus atoms form strong covalent bonds with carbon nanotube.