Properties of Boron Nanocrystals, Borophene, and its Polymorphs

Boron and its polymorphs show a remarkable ability to form stable compounds due to their flexible and strong bonding capacity. They form stable multi-center two-electron bonds and two-center two-electron covalent bonds. They have been formed flexible two-dimensional (2D) materials that differ significantly from other well-studied 2D materials. Due to the remarkable properties of the 2D boron nanocrystals, and nanosheets, significant interest has been gaining in the recent past year. One of the great achievements of the syntheses of 2D boron sheets is known as borophene. It has gained notable attention due to its unique physical and chemical properties and is hence utilized in broad applications including electrochemical and optical sensors and biosensors, piezoelectric devices, catalysis reactions, energy storage devices, etc. In addition to this, boron also exists in several complex forms such as boron carbide (B4C), boron nitride (BN) i.e. hexagonal boron nitride (hBN), rhombohedral boron nitride (rBN), zinc-blende boron nitride (cBN), and wurtzite boron nitride (wBN) which shown the unique physical and chemical properties. In this chapter, we have discussed a brief overview of the structural characteristics and different properties of boron nanocrystals, borophene, and other 2D boron polymorphs.