Preparation and Optical Properties of Boron Nitride Nanomaterials and their Nanocomposite Films

Hexagonal boron nitride (h-BN) represents one of the most popular two-dimensional (2D) materials whose excellent properties are expected to have great potentials in electronics and optoelectronics. The fabricated h-BN nanostructures are usually composed of dangling bonds at the edges and saturated sp2 BN bonds in the domains, in general, which also contain carbon, oxygen, and hydrogen impurities. As far as we know, the defects play a primary role in creating new properties of 2D h-BN, for example, enhanced absorption, emerging fluorescence, and photocatalytic activity. Therefore, managing and tailoring defects in h-BN systems is a key process for the exploitation of their advanced functions. However, clear correspondences of defects and properties still have not been well established in terms of h-BN basic research. In particular, the present carbon impurities heavily cause uncertainty in modulating and understanding the optical properties of h-BN systems. Herein, this Thesis has mainly focused on exploring the relationship between structure defects and optical properties of h-BN nanosheets and nanodots. Both the BN sheets and dots are produced using a carbon-free process for the targets of introducing special defects and thereby understanding the corresponding defect-property causality. Simultaneously, quantum chemistry calculations have been carried out to support the experimental findings. Subsequently, sol-gel chemistry has been applied to fabricate their nanocomposites by respectively incorporating the synthesized sheets and dots into transparent films (i.e. titania TiO2 and silica SiO2), which determine their possibility in solid-state devices in the fields of photocatalysis and light-emitting applications.