Density Functional Theory Investigation of Phosphine gas Adsorption to Carbon and Silicon Carbide Nanotubes

Phosphine (PH3) is a toxic and harmful gas released by the reaction of aluminum phosphide or rice pill in the presence of water, water vapor or stomach acid. Poisoning caused by phosphine is more suicidal and two thirds of the poisoned ones die. In this paper, the structural and electronic properties of (10,0) carbon nanotube and SiC nanotube have been investigated through density functional theory. The PH3 molecule was first placed at the distance about the sum of atomic radius of C/Si of nanotube and P/H of phosphine molecule, inside and outside the nanotube from both H and P atom sides. Then the structure was completely relaxed the electronic calculations were performed on relaxed structures. The results show that SWCNT can weakly adsorb PH3 molecule. However, SiC nanotube has lower adsorption energy toward phosphine and its electronic properties change more after adsorbing PH3 inside or outside the silicon carbide nanotube. Therefore this nanotube is potentially a good candidate for detecting and adsorbing PH3 molecules. Partial densities of state calculations were also performed to find the origin of each adsorption.