Enhancement in hydrogen molecule adsorption on B12N12 nano-cluster by decoration of nickel

Abstract

We present here results from detailed investigation on the adsorption property of H2 on the surface of B12N12 (BN) and Ni-decorated B12N12 (Ni-BN) nano-clusters through density functional theory (DFT) methods. First, the adsorption of Ni on BN nano-cage resulted in optimization of two distinct geometries (P1 and P2) differing in orientation of nickel on the surface of the nano-cage. The binding properties have been calculated and analyzed theoretically for both geometries of Ni-BN (P1 and P2) in terms of binding energies, band structures, total density of states, and natural bond orbital (NBO) charges. The nickel binds more strongly to BN nano-cage in P1 compared to P2, as revealed from energetic and electronic properties. Hydrogen adsorption has also been studied on Ni-BN (both P1 and P2), and compared with that of bare BN nano-cage. H2 adsorption capacity for nickel decorated BN nano-cage (Ni-BN) is considerably enhanced while there is very low adsorption capacity for pristine BN. Although, decoration of Ni in P1 geometry releases slightly higher energy (∼444 kJ/mol versus ∼399 kJ/mol for P2), the latter is better adsorbent for H2 molecule. H2 adsorption on Ni-BN in P2 geometry is more exothermic (∼144 kJ/mol versus ∼108 kJ/mol for position P1). The band gap of Ni-BN nano-cages increases upon interaction with hydrogen, and the effect is more pronounced for P2 geometry compared to P1. Incorporation of Ni enhances the H2 adsorption capacity of BN cluster, significantly.