Advanced nano boron nitride architectures: Synthesis, properties and emerging applications

Hexagonal boron nitride (h-BN) is an extraordinarily tough material that is chemically and thermally resistant to extreme environments, uniquely electrically insulating yet possessing exceptionally high thermal conductivity. Owing to these exotic and outstanding properties, and the ability to be controllably fabricated at large-scale, various architectures of low-dimensional h-BN have emerged as promising candidates for a myriad of applications. This review provides a comprehensive and holistic account of the most widely utilized fabrication techniques with emphasis on new advancements for various forms of nano-BN architectures ranging from 0D quantum dots, 1D nanotubes and nanoribbons, 2D nanosheets and 3D frameworks of BN. These techniques encompass improved synthesis progresses by chemical vapor deposition, scalable forms of exfoliation, bottom-up and top-down hydrothermal/solvothermal processes and assembly of 3D structures by freeze-casting. Furthermore, the functional properties and utilization of these nano-BN architectures for various novel and evolving applications including thermal management for modern electronics, deep ultraviolet optoelectronics, single photon quantum emitters, protective coatings against corrosion, high-performance polymer dielectrics, space instrumentation, drug delivery, tissue engineering and biosensing are extensively elaborated. Finally, several major challenges and limitations of the existing fabrication technologies that hinder further upscaling and commercialization are highlighted, which offer new opportunities for the development of advanced BN nanostructures toward diverse emerging and future applications.