A general route for the convenient synthesis of crystalline hexagonal boron nitride micromesh at mild temperature

Abstract

In this study, hexagonal boron nitride (h-BN) micromeshes with high crystallinity and yield have been prepared by B₂O₃, Mg and NaN₃ in a stainless steel autoclave at 450 °C, which have diameters of up to 100 µm, thickness of ∼210 nm and pore size of 2.8 µm on average. A near-band edge emission at 217 nm of these micromeshes has been observed through the photoluminescence (PL) spectra. Their formation mechanism was considered through an oriented aggregation process, in which the in-situ produced MgO microparticles served as template. As B₂O₃ was substituted by other boron sources (such as H₃BO₃, Na₂B₄O₇, NH₄HB₄O₇ or Mg(BO₂)₂·H₂O), h-BN micromeshes with different pore sizes could also be produced; therefore, it is a general way for the convenient synthesis of crystalline h-BN micromeshes. The as-obtained product is promising as a catalyst support, in chemical filtration and in separations under severe operating conditions.