Adsorption of CO, SO2, HCN, NH3, and H2CO on zigzag GaP nanotubes: a QM/MM study

Abstract

The interactions of the single-walled zigzag (5, 0), (6, 0), and (7, 0) GaP nanotubes (GaPNTs) with CO, SO₂, HCN, NH₃, and H₂CO molecules are theoretically studied at the ONIOM(B3LYP/6-31G(d):UFF) level. A pyrene-like ring of the nanotube is chosen as an adsorption site in the high layer of the ONIOM calculations for the adsorption of a single molecule. Binding energy, Gibbs free energy change, density of states, and Mulliken charge transfer are computed to analyze the nature of the binding between GaPNT and the adsorbate molecule. The bindings of CO and H₂CO towards GaPNTs are weaker than those of NH₃, SO₂, and HCN molecules. The strongest adsorption is found to be with NH₃. The dispersion corrected functional (wB97XD) has been introduced to compare the results with those of the B3LYP functional.