Hexagonal boron nitride (h-BN) belongs to a class of crystalline compounds with layered structure: it consists of parallel honeycomb layers, in which hexagons vertices are alternatively occupied by boron (B) and nitrogen (N) atoms. Intra-layer bonds between neighboring atoms are strong, mostly of covalent type, while inter-layer bonds are week, mostly of van der Waals type. Correspondingly, intra-layer B–N bonds are significantly shorter than that of inter-layer B–N bonds. Bonding in h-BN is with a small ionic deal related to opposite signs of effective charges possessed by the constituent B and N atoms – positive and negative, respectively.

Fig. 1. Schematic view of the cross section of h-BN crystal with nano-sized islands on the free flat surface.

Character of bonding determines the reconstruction that takes place in the free surface layer – B and N atoms can be rather easily displaced in opposite directions perpendicular to the initial layer. Thus, surface reconstruction in h-BN involves splitting the surface layer into two sublayers, which consists of atoms with positive and negative effective charges. It implies the formation of an ultra-thin dipole layer at the free surface.

静态偶极层correspondin诱导g static electric field, which in the limit of an ideally flat infinitive crystalline surface, is concentrated between sublayers. This makes flat h-BN surfaces practically non-reactive with environment. But, if the material is nanostructured – consists of nano-sized particles, grains, pores, etc. – there is also expected the emergence of a near-surface electric field of significance strength. This novel nano-effect explains high physical reactivity frequently revealed by the nanostructured h-BN: due to non-zero near-surface field it can polarize and attract various particles from the environment. In particular, nanoporous boron nitride fibers are found to be an effective material capturing large non-polar molecules of organic pollutants from aqueous solutions.

Levan Chkhartishvili
Department of Engineering Physics, Georgian Technical University, Tbilisi, Georgia

Publication

Nanoparticle Near-Surface Electric Field.
Chkhartishvili L
Nanoscale Res Lett. 2016 Dec

Read offline:

Related Articles:

	Optimal optoelectronic properties of MoS2/h-BN/WSe2 van der…With the development of next generation semiconductor photoelectric devices towards miniaturization, high performance and high integration, traditional bulk materials are facing enormous challenges. The discovery of graphene has opened the…
	Short hydrogen bonds in proteins and their quantum…The assembly of linear polypeptide chains into functional three-dimensional protein architectures involves a unique force called hydrogen bonding. A typical hydrogen bond forms when the donor and acceptor groups approach…
	What treatment is really medically and economically…Currently, direct-acting agent (DAA) therapies have high efficacy and safety and are the main strategy to eliminate hepatitis C virus (HCV) worldwide. Some DAA therapies are also effective for HCV-infected…
	The algal organic matter: A novel carbon source to enhance…In recent years, nitrogen pollution, especially nitrate is an important problem faced by lots of reservoirs. Excessive nitrogen levels can cause water eutrophication, resulting in deterioration of water quality by…
	Sustainable solutions: Tamarind Seed Kernel powder (TKP)…The majority of petroleum-based adhesives applied in the wood industry today, particularly formaldehyde-based adhesives. Their application trend is increasing due to their wide availability, superior bonding, durability, and resistance to…
	Turbulent flow simulation using a parallel discontinuous…Turbulent flow is omnipresent in everyday life. When one flies in an aircraft or drives a car, the flow around the vehicle is mostly turbulent. Understanding turbulence has practical importance…