First-principle investigation of thiophene adsorption on TM (Ni/Co/Mn)-doped (ZnO)15 nanotube

The adsorption of thiophene on transition metal (Ni/Co/Mn)-doped (ZnO)15 nanotube is investigated using density functional theory calculation. Different adsorption possibilities have been investigated. It is found that the stability of the nanotube increases with the doping of the transition metal (Ni/Co/Mn) atom, and the doping of transition metal (Ni/Co/Mn) atom should be mainly responsible for the reduction of the energy gap. We also observed an elongation of the SC bond in adsorbed thiophene in Ni/Co/Mn-doped (ZnO)15 adsorption systems, compared with those of adsorbed thiophene in pristine (ZnO)15 adsorption systems, illustrating the SC bonds in adsorbed thiophene are active by transition metal atom in Ni/Co/Mn-doped (ZnO)15 nanotubes. Molecular orbital results show that π-backdonation is found in η2 bonding mode. Moreover, compared with the vibrational frequencies of free thiophene, the ν(CC)sym and ν(CS)as bands of η2 bonding mode are shifted to lower wavenumber.