In silico insight into ammonia adsorption on pristine and X-doped phosphorene (X = B, C, N, O, Si, and Ni)

Abstract

In this study the details of ammonia adsorption on pristine and doped single layered black phosphorous (SBP) have been investigated based on density functional theory. Geometry optimization were carried using different density functional such as B3LYP, PBE and B97D in conjugate with 6–31+G* basis set. From geometrical point of view, doping heteroatoms causes internal distortion in SBP which was found large for B-, C-, N- and O-doped BP sheet(s). Doping heteroatom also decreases the Eg values in all of the studied SBP systems. Calculation showed that the largest adsorption energies for ammonia on SBP belong to B-, Si, and Ni-doped system(s) with the energy values of −43.3, −35.3 and −17.05kcal/mol, respectively. It was found that the adsorption energies for pristine and C-, N- and O-doped SBP are not significant (Ead<8.6kcal/mol). We suggested that metal dopants (B, Ni and Si) improve the reactivity of SBP to ammonia molecule in contrast to pristine and non-metal doped-SBP (C, N and O). Our results showed that whereas the substitution of most dopants has a significant effect on the gap width of the doped system, nitrogen doping has no important influence on gap width and overall shape of DOS curve. Adsorption of ammonia on the N-, C-, and O-doped systems had no significant effect on the electronic structure of these systems, whereas it changed the DOS curves of Si-, and Ni-doped systems slightly. In the case of B-doped SBP, ammonia absorption leaded to the remarkable change in DOS, accompanied by fading of a small peak in the gap region.