Dimension Engineering of Boron Nitride Nanostructures through Catalytic Flash Joule Heating

Boron nitride (BN) is well-known for its excellent thermal conductivity, high chemical stability, and low dielectric constant, making it widely used as a lubricant, thermal management material, and electrical insulator. For different applications, the nanostructure of BN plays a prominent role. In particular, boron nitride nanotubes (BNNTs) are preferred for enhancing the properties in specific directions. Traditional BNNT synthetic methods often require valuable precursors and catalysts and prolonged reaction time for structure engineering, limiting their practical applications. Here, we present a dimension engineering strategy to controllably synthesize one-dimensional BNNTs and two-dimensional nanosheets (BNNSs) by flash Joule heating (FJH) within 1 min. The scalable production of ∼5 g is achieved per batch. During BN synthesis, sulfur is identified as a crucial additive that accelerates precursor dehydration and facilitates nanotube formation. When applied as additives in composites, BNNTs exhibit enhanced mechanical strength and thermal conductivity compared to BNNSs, highlighting the necessity of BN dimension engineering for diverse applications. This work offers a feasible strategy for tailoring BN nanostructures and optimizing their properties, with potential applicability in the synthesis of other nanomaterials beyond BN.