Application of pristine and Ni-decorated B12P12 nano-clusters as superior media for acetylene and ethylene adsorption: DFT calculations

Abstract

In this study, density functional theory (DFT) method with B3LYP-D and MPW1PW91 functionals is carried out to explicate the adsorption properties of small unsaturated hydrocarbons (acetylene and ethylene molecules) on the surfaces of pristine and Ni-decorated B12P12 nano-clusters. More specifically, binding energies, natural bond orbital (NBO) charge transfer, dipole moment, frontier molecular orbitals, density of states (DOS), and global indices of activities are analyzed to deeply perceive the fluctuations of electronic and chemical properties of pure and Ni-decorated B12P12 nano-cage upon acetylene and ethylene adsorption. Our theoretical findings indicate that Ni atom can be adsorbed on the surface of B12P12 nano-cage in three distinct configurations (P1, P2, and P3), where P1 is found as the most stable geometry. Although the acetylene (ethylene) molecule is weakly physisorbed on the surface of pristine B12P12 nano-cage with adsorption energy of -34.1 (-30.7) kJ mole(-1), a significant improvement in their adsorption energies is found by utilizing Ni-decorated B12P12 as the adsorbent. The highest adsorption energy for acetylene (ethylene) adsorption on Ni-decorated B12P12 is -270.6 (-232.0) kJ mole(-1) in P2 (P3) geometry, suggesting that Ni decoration of B12P12 nano-cage enhances its capability toward acetylene and ethylene adsorption. It is also discovered the band gap of pristine B12P12 nano-cage decreases after complexation with Ni atom, and increases again upon adsorption of acetylene and ethylene molecules on its surface. In addition, the values of softness and electrophilicity for Ni-decorated B12P12 are higher than other structures. Our results suggest that Ni-decorated B12P12 nano-clusters show promise in acetylene and ethylene molecules adsorption. (C) 2017 Elsevier B.V. All rights reserved.