Two-dimensional (2D) materials have attracted major attention in the last decade for their unique properties and promise for next generation electronics and energy conversion devices. The discovery of graphene and hexagonal boron nitride (h-BN) in particular has inspired a fervent search for other 2D materials with unexpected and useful properties.
Hexagonal boron nitride 2d is a layered material with a honeycomb structure that strongly resembles graphite. Hexagonal boron atomic layers are covalently bonded to one another in the basal planes and weakly interact with each other in the interlayers, known as the van der Waals forces. This unusually strong intra-layer bonding reduces electron delocalization and makes h-BN one of the best electrical insulators. Its low dielectric constant and high temperature stability make it a promising candidate for next-generation nanoelectronics, optoelectronics, and electrocatalysis.
The crystal structure of h-BN is isostructural with diamond and graphite. The cubic form of boron nitride (c-BN) is less stable than the hexagonal h-BN, but the conversion rate between the two forms is negligible at room temperature. Cubic BN and hex-h-BN are also isomorphous with carbon materials such as ternary tungsten carbide (W-C).
2D-hBN has several intriguing intrinsic properties that are of great interest for various applications. These include resistance to oxidation, extreme mechanical hardness, high thermal conductivity, photoluminescence and chemical inertness. In addition, it has a high surface energy that enables facile functionalization with organic molecules. This article provides a systematic elaboration of the physics and engineering of 2D-hBN and reviews state-of-the-art synthesis methods including mechanical exfoliation, liquid exfoliation, chemical vapor deposition, ion insertion and pulsed laser deposition.