Boron Nitride Nanotube, Its Chemistry and Application in Sensors and Transistors

Boron nitride nanotube (BNNT) is another emerging mankind one dimensional nanomaterial discovered at the same time frame around the years of 1990 as its counterpart carbon nanotube (CNT), but it has been much delayed in its synthesis for a large scale, its chemistry and application due to its differences in production and material characteristics from CNT. BNNT possesses a compelling set of intrinsic properties similar to CNT, such as one-dimensional tubular structures, light weight, high mechanical strength, and high thermal conductivity. But unlike CNT, BNNT is an electrical insulator with a wide bandgap about 5.5 eV, and has a hetero-atomic network of B and N in turn instead of homo-atomic of C network structure, therefore, BNNT has additional characteristics such as transparency in visible light, high thermal stability and high oxidation resistance over 900 ^oC in air. These properties make them high potential in many applications such as high-temperature and extreme environments, transparent armor materials, and radiation shielding protections. Especially, the polarity of B-N bonds in the BNNT network offers unique surface chemistry that can be taken in full advantages for sensing applications, for instance, due to interfacial compatibility and reactivity to its environment. We will present the use of HABS-BNNT materials produced at the National Research Council Canada (NRC) through thermal induction plasma process and the development of the surface chemistry by in-situ B-N bond cleavage with liquid bromine treatment in aqueous solution, leading to OH and amino (NH₂) dual surface functionalities at the same steps. Such functionalized BNNTs are highly soluble in aqueous and polar organic solvents by themselves without adding any surface agent. Our report will include up to today’s results that such functionalized BNNTs as a sensing material for the active coating layers on optical fiber devices as well as a dielectric material for the applications in capacitors and in organic thin film transistors (OTFTs) for improving their performance and shelf life. An indicative outlook will be briefly discussed in the further development of BNNT-integrated transistors.