Book excerpt: A hexagonal boron nitride nanosheet (BNNS) is an atomic-thick 2D material that exhibits many interesting properties such as high chemical stability and excellent mechanical and thermal properties. In Chapter One, the authors introduce two methods for the exfoliation of BNNS from hexagonal boron nitride (hBN). Then, methodologies for the surface functionalisation and nanocomposite construction are demonstrated by two BNNS based nanocomposites. The catalytic performance of the BNNS based nanocomposites is also evaluated and discussed in detail. Chapter two evaluates the formation of rolled hexagonal boron nitride nano-sheets (h-BN nanoscrolls) on their unique morphology, magnetic properties and applications. Due to the high chemical and thermal stabilities, as well as atomically smooth surfaces with free of dangling bonds, hBN has been used as barriers, passivation and support layers in 2D electronic devices, to maximise the electrical and optical characterisation of 2D materials. However, there still remains a challenge in obtaining large-area and high-quality hBN film for real 2D electronic devices. Chapter Three focuses on chemical vapor deposition (CVD), a promising method to overcome these limitations. Chapter Four discusses how a boron doped armchair graphene ribbon has been shown by cyclic voltammetry to be a potential catalyst to replace platinum, however the reaction catalysed was not identified. The authors use density functional calculations to show the reaction catalysed is likely dissociation of HO2. Chapter Five reveals a novel and industrially feasible route to incorporate boron nitride nanoparticles (BNNPs) in radiation-shielding aerospace structural materials. Chapter Six deals with the preparation and characterisation of boron nitride nanotube (BNNT)-reinforced biopolyester matrices. The morphology, hydrophilicity, biodegradability, cytotoxicity, thermal, mechanical, tribological and antibacterial properties of the resulting nanocomposites are discussed in detail. Chapter Seven presents theoretical estimations regarding the compressive buckling response of single walled boron nitride nanotubes (SWBNNTs), which have a similar crystal structure as single walled carbon nanotubes (SWCNTs). Moreover, SWBNNTs have excellent mechanical, insulating and dielectric properties. Finally, Chapter Eight shows how the different exchange mechanisms can be distinguished and measured by studying solid films where part of the 3He is replaced by immobile Ne atoms. The authors also show how the formation energy of vacancies and vacancy tunneling frequency can be obtained from NMR studies at high temperature.