Synthesizing Boron Nitride Quantum Dots in Microdroplets.

Song, Xiaowei; Lyu, Lecheng; Xu, Jinheng; Li, Chao; Alzamil, Abdulaziz A; Bikdash, Rashed Saed; Younis, Muhammad Naeem; Kamran, Muhammad et al. · Nano Lett · 2026

basic_science · Level V

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Abstract

We demonstrate that water microdroplets create a highly reactive interfacial environment that enables the rapid, room-temperature synthesis of boron nitride quantum dots (BNQDs). Using a borane ammonia complex (BH<sub>3</sub>NH<sub>3</sub>) and a boric acid-ammonia system as precursors, we obtain green- and blue-emissive BNQDs, respectively, under ambient conditions. Mass spectrometry reveals a dehydrogenative cyclization pathway for BH<sub>3</sub>NH<sub>3</sub>, delineates the size distribution of B<sub><i>x</i></sub>N<sub><i>y</i></sub> clusters, and reveals reaction kinetics accelerated by 6 orders of magnitude relative to conventional bulk hydrothermal synthesis. Hydroxyl radicals (OH<sup>•</sup>), generated from interfacial water and entrained oxygen, act as key oxidants driving stepwise dehydrogenation of BH<sub>3</sub>NH<sub>3</sub>. For the boric acid-ammonia system, the dehydration and deamination process is accelerated on the air-water interface. In a spraying-recirculating microdroplet reactor, milligram-scale quantities of BNQDs with an average diameter of ∼8.5 nm are produced within 1 h, establishing a green, bottom-up route for nanomaterial synthesis by exploiting the intrinsic reactivity of water microdroplets.