Ammonia-Activated High-Pressure laser ablation with Cu mesh assistance enables High-Yield BNNT synthesis for chip thermal management

Shrinking device dimensions and escalating heat fluxes bottleneck chip thermal management. Boron nitride nanotubes (BNNTs) combine high thermal conductivity with a wide band gap, making them attractive fillers for composites. However, deployment of BNNTs remains constrained by limited production throughput and associated cost barriers. Here, an ammonia-activated high-pressure laser ablation strategy with non-consumable Cu mesh assistance (A-HPLA-CuM) is developed for BNNT synthesis, yielding BNNT-rich fibrous product at 692.7 mg h −1 using a scalable setup. The obtained BNNTs exhibit high crystallinity, with a mean diameter of 9 nm and a mean wall number of 7. Compared with conventional laser ablation and Cu mesh-assisted synthesis in N 2 , ammonia activation is associated with a higher production rate while maintaining product quality. The improvement is likely associated with NH 3 -derived B-N–H intermediates that may facilitate B-N conversion, together with Cu mesh assistance that may help maintain a favorable local reaction environment. As a proof-of-concept validation, the as-synthesized BNNTs were evaluated in composite films. At 50 wt% BNNT loading, the film delivers an in-plane thermal conductivity of 15.9 W m −1 K −1 and reduces temperature by 4.67 ℃ relative to the BN-filled control after 30 s. This work demonstrates A-HPLA-CuM as a scalable route for BNNT synthesis.