2D boron nitride nanosheets (BNNS) prepared by high-pressure homogenisation: structure and morphology

Abstract

2D Boron Nitride Nano-sheets (BNNS) were prepared using a high-pressure homogenisation process to exfoliate bulk hexagonal boron nitride (h-BN). The effectiveness of this process was studied by characterising bulk h-BN and BNNS post-processing using numerous techniques. The BNNS produced was composed of a mixture of sheets having lengths on the nanometre (nm) scale, but lateral thicknesses on the micron (μm) length scale. The product was a macro-porous material containing slit-like pores with a surface area of 170 m² g⁻¹. It had a polycrystalline structure with d₀₀₂ = 0.335 nm and L₀₀₂ = 2 nm. From the sharp E_2g peak in the Raman spectrum at 1360 cm⁻¹ (FWHM = 12.5 cm⁻¹), the sheets had a low defect density and were highly exfoliated. X-Ray photoelectron spectroscopy (XPS) studies detected B–OH and N–H groups on the BNNS surface and the presence of residual surfactant. Contact angle measurements (60° ± 3° (0 s); 40° ± 2° (10 s)) confirmed a hydrophilic surface. The BNNS was thermally stable under oxidative conditions up to 323 °C.