First-principles Study Of The Adsorption On B(N)-doped SWCNTs

Researches on carbon nanotubes (CNTs) reinforced metal matrix composites (MMCs) are booming in recent years. The use of doping, coating and electroplating etc. to improve the binding of interfaces has attracted much attention. In this paper, first principles calculations based on density functional theory (DFT) were carried out to evaluate the effect of B (N)-doping on adsorption of a metal (Mg, Al) atom (chain) on armchair and zigzag SWCNTs with opened-cap. The stable positions, the geometric structures and binding energies of metal atoms adsorbed on CNTs were investigated. The adsorption and the doping influences on graphene were also studied to simulate the SWCNT with a large diameter.The adsorption of Mg atom on both two kinds of CNTs is weak, with binding energies nearly zero. Although there is stronger interaction between Al atom and CNTs, it remains a weak physical adsorption, which could not construct an effective interfacial binding in Mg, Al based composites. Compared with undoped CNTs, the B (N)-dopant changes the electronic structures of the CNTs. The B-doping forms electron-rich states, while N-doping induces electron-deficient states. The interaction of Mg (Al) atom adsorbed on pristine SWCNTs which is normally very weak, can be enhanced upon functionalization by A-doped (A=boron, nitrogen) substituting. Especially B-doped increase the binding energy dramatically both in armchair and zigzag SWCNTs. The binding energies of metal atoms in the graphene models are lower than in the CNTs models with small diameter. In addition, codoping of B and N failed to signigicantly improve the adsorption of the Mg (Al) atom on CNTs.The theoretical calculations show that the doping is help to improve the interfacial binding between the CNTs and Al (Mg), which provide a potential guide for the designing of the CNTs reinforced MMCs. However, the modeling is just first step of design to explain and improve the reaction of interfaces between Metal atoms and CNTs, further study on the interfacial models should be carried out.