Development of practical production methods of boron nitride nanotubes

2022 Fiscal Year Final Research Report

• Project/Area Number: 21K18858
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 27:Chemical engineering and related fields
• Research Institution: Waseda University
• Principal Investigator: Noda Suguru 早稲田大学, 理工学術院, 教授 (50312997)
• Project Period (FY): 2021-07-09 – 2023-03-31
• Keywords: 窒化ホウ素ナノチューブ / 化学気相成長法 / 鋳型合成法 / 実用合成プロセス / ホウ素原料 / ナノ材料

Outline of Final Research Achievements

Boron nitride nanotubes (BNNTs) are insulating and colorless, opposite to carbon nanotubes (CNTs). Various devices combining both can be envisioned, but BNNTs are expensive. In this study, the synthesis of BNNTs using an inexpensive and easy-to-handle boron source was investigated. Using B2O2 vapor from the reaction of boron and water vapor and H3BO3 vapor from sublimation of boric acid or mist supply of its aqueous solution, BNNTs were synthesized by chemical vapor deposition (CVD) using ammonia nitrogen as source and metal nanoparticle as catalyst, but of poor quality and in low quantity. Then, the template synthesis was investigated using CNTs, which have become inexpensive. CNT films were coated with BN by impregnation with a boric acid solution and nitridation with ammonia, and BNNT films were obtained by combustion removal of the CNTs.

Free Research Field

反応工学、材料プロセス、ナノテクノロジー

Academic Significance and Societal Importance of the Research Achievements

現状、BNNTは数千℃の高温で物理的手法により合成されており、1 gあたり数万円と非常に高価である。より実用的なCVD法も検討されているが、高価で扱いの難しいホウ素源を用い微量合成することが多い。安価で扱い安いホウ素とホウ酸を用いたホウ素源供給は実用上の価値が高い。また、2B(s)+2H2O(g)→B2O2(g)+2H2(g)の固-気反応による蒸気供給は、学術的にも意義がある。鋳型合成法は、量産と低コスト化の進んだCNTで予め所望の構造体を作り、BNコートとCNT除去によりBNNT構造体に変換する技術であり、透明エアロゾルフィルタや高耐熱性電池セパレータなどへの応用が期待される。