Interaction of Boron Clusters with Aantisite Defective BNNTs: A DFT Study

Functionalization of the homonuclear nitrogen-nitrogen bonds of antisite defective (4, 4)BNNTs was investigated by quantum chemical calculations through their interaction with a B6boron cluster. Two types of antisite defects were considered, exchange antisite defect producedby 180º rotation of a BN bond, and substitutional antisite defect produced by the substitution of aB atom with an N atom. Being able to stabilize an extra-added electron, the symmetricoctahedral B6— ion shows magnetic and semiconductor behaviors which make the B6 particle apromising candidate for the search of novel nano-devices [1]. Six N-N bonds at the edges, nearthe edges, and in the middle of antisite defective BNNTs, lying diagonal or perpendicular to thetube axis, are considered for functionalization. The M06-2X functional in combination with 6-311+G (d, p) basis set is used for geometry optimizations to include correlation effects [2]. Basedon our results, two-fold coordination together (double ring configuration of boron cluster) withthe drastic structural changes and N-N bond cleavage (3.13-3.75 Å) occur between double ringB6 and BNNT surface. B-B bond lengths of adsorbed double ring B6 are obtained to be within1.571–1.838 Å, shorter than those in a free B6 octahedron. The negative values of reactionenergies indicate the exothermic character of the functionalization process. Functionalization ofN-N bonds at the edge or near the edges of the narrower tubes is also found to be more favorablethan those in the middle of the tubes. In the most stable complex antisite defective BNNT−B6,involving N-N bond at the edge, the B6 molecule pulls apart the N-N bond and becomes anintegral part of the tube by expanding the original hexagonal ring. However, in other antisitedefective BNNT-B6 clusters, involving N-N bonds at the middle of the tubes or near the edges,double ring B6 acts as a bridge at the top of the decagon of BNNTs [3].

کلیدواژه ها:

Antisite Defective BNNTs ، Boron Clusters ، DFT