Turbostratic Boron–Carbon–Nitrogen and Boron Nitride by Flash Joule Heating

Turbostratic layers in 2D materials have an interlayer misalignment. The lack of alignment expands the intrinsic interlayer distances and weakens the optical and electronic interactions between adjacent layers. This introduces properties distinct from those structures with well‐aligned lattices and strong coupling interactions. However, direct and rapid synthesis of turbostratic materials remains a challenge owing to their thermodynamically metastable properties. Here, a flash Joule heating (FJH) method to achieve bulk synthesis of boron–carbon–nitrogen ternary compounds with turbostratic structures by a kinetically controlled ultrafast cooling process that takes place within milliseconds (103 to 104 K s−1) is reported. Theoretical calculations support the existence of turbostratic structures and provide estimates of the energy barriers with respect to conversion into the corresponding well‐aligned counterparts. When using non‐carbon conductive additives, a direct synthesis of boron nitride is possible. The turbostratic nature facilitates mechanical exfoliation and more stable dispersions. Accordingly, the addition of flash products to a poly(vinyl alcohol) nanocomposite film coating a copper surface greatly improves the copper's resistance to corrosion in 0.5 m sulfuric acid or 3.5 wt% saline solution. FJH allows the use of bulk materials as reactants and provides a rapid approach to large quantities of the hitherto hard‐to‐access turbostratic materials. Turbostratic boron–carbon–nitrogen and boron nitride compounds with various chemical compositions can be prepared by the ultrafast and solvent‐free flash Joule heating method. The obtained flash boron–carbon–nitrogen (f‐BCN) is easily exfoliated via various mechanical methods. Compared to commercial hexagonal boron nitride nanoplates, flash boron nitride sheets demonstrate more stable dispersibility in aqueous solution. Furthermore, the addition of f‐BCN as barrier fillers in poly(vinyl alcohol) nanocomposites shows higher corrosion protection efficiency, ≈97.3% in 0.5 m H2SO4 and ≈92.1% in 3.5 wt% NaCl (aq).