Revealing the Effect of Sulfur Compounds for Low-Temperature Synthesis of Boron Nitride Nanotubes from Boron Minerals

Boron nitride nanotubes (BNNTs), the structural analogues to carbon nanotubes (CNTs), attracted considerable attention due to their excellent properties. However, the synthesis of BNNTs suffers from high-temperature requirement, which increases the cost and adds complexity to instruments (arc-discharge, plasma-assisted CVD, etc.), preventing further exploration of BNNTs and use of harmful chemicals (catalytic chemical vapor deposition) resulting in unwanted byproducts. Here, we demonstrate sulfur-containing compound-assisted synthesis of BNNTs at a relatively low temperature of 1050 °C from colemanite via a chemical vapor deposition (CVD) method. Comparison between thiophene, l-cystine, and l-methionine revealed that thiophene is the most effective sulfur compound with more stable decomposition products and low vapor pressure. Moreover, we have evaluated ulexite and etidot-67 as an alternative to colemanite. We believe that our findings can offer solutions to commonly encountered problems of BNNT synthesis in terms of high energy consumption and precursor cost, leading to broader use of BNNTs in various applications.