Boron nitride nanotubes: A review of recent progress on purification methods and techniques

Abstract Boron nitride nanotubes (BNNTs) will be one of the most important materials of this century. Recent synthetic advances have made BNNTs viable candidates for advanced multifunctional materials. Like carbon nanotubes and graphene, BNNTs and h-BN have extraordinary physical properties. Unlike CNTs, BNNTs have a wideband gap; they are piezoelectric, have neutron radiation shielding capability, and can withstand degradation up to 1000 °C. BNNTs could be the next big leap for nanocomposite advanced applications; however, significant scientific challenges must be addressed. Predominantly, large-scale synthesis techniques are immature. Production products require careful characterization, analysis, and purification. Impurities such as boron, amorphous BN, and h-BN lead to difficulty studying chemical modification and translation of BNNT properties. This review synthesizes relevant literature and state-of-the-art techniques regarding purification methods of BNNTs, classified as physical, chemical, and multi-step techniques and their applications. The review also discusses BNNT synthesis methods and future research directions. Graphical abstract