Theoretical study on wetting behavior of B-SWNT: Effects of doping concentration

Abstract

Wettability is a key property of single-walled carbon nanotubes (SWNTs), governed both by the chemical composition and geometrical microstructure of the contact surface. Wettability of SWNTs can be enhanced via doping with heteroatoms such as boron or nitrogen to tune the electronic properties of SWNTs. We investigated the adsorption of the water monomer and dimer on pristine and B-doped (5,5) SWNTs by first-principles calculations. The calculated adsorption energy of the water monomer and dimer on pristine (5,5) SWNTs was low. The water dimer can form BO dative bonds with B-doped (5,5) SWNTs, enhancing interactions among each other. A higher adsorption energy of the water dimer was obtained with higher B-doping concentration. Additionally, electronic property analysis showed electron transfer from the water dimer to the boron of the SWNT, forming a BO dative bond, then from the SWNT to the water dimer through an OH⋯π interaction. The interactions between water dimer and SWNT are strongly cooperative. We further compared the adsorption energies of the water dimer and trimer on B-doped SWNTs with their cohesive energies. The adsorption energies increase due to cooperative effects, thereby enhancing wettability. We can expect that B-doped SWNTs can efficiently improve the wettability of carbon nanotubes.