Thermally induced formation of 2D hexagonal BN nanoplates with tunable characteristics

We have investigated a thermally induced combustion route for preparing 2D hexagonal BN nanoplates from B₂O₃+(3+0.5k)Mg+kNH₄Cl solid system, for k=1–4 interval. Temperature–time profiles recorded by thermocouples indicated the existence of two sequential exothermic processes in the combustion wave leading to the BN nanoplates formation. The resulting BN nanoplates were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy, PL spectrometry, and Brunauer–Emmett–Teller surface area analysis. It was found that B₂O₃ was converted into BN completely (by XRD) at 1450–1930 °C within tens of seconds in a single-step synthesis process. The BN prepared at a k=1–4 interval comprised well-shaped nanoplates with an average edge length ranging from 50 nm to several micrometer and thickness from 5 to 100 nm. The specific surface area of BN nanoplates was 13.7 g/m² for k=2 and 28.4 m²/g for k=4. - Graphical abstract: 2D hexagonal BN nanoplates with an average edge length ranging from 50 nm to several micrometer and thickness from 5 to 100 nm were prepared by combustion of B₂O₃+(3+0.5k)Mg+kNH₄Cl solid mixture in nitrogen atmosphere. - Highlights: • Thermally induced combustion route was developed for synthesizing BN nanoplates from B₂O₃. • Mg was used as reductive agent and NH₄Cl as an effective nitrogen source. • Temperature–time profiles and the combustion parameters were recorded and discussed. • BN with an average edge length from 50 nm to several micrometer and thickness from 5 to 100 nm were prepared. • Our study clarifies the formation mechanism of BN in the combustion wave