Defect Functionalization of Hexagonal Boron Nitride Nanosheets

A pristine hexagonal boron nitride (h-BN) powder sample with layered crystalline shectlike particles of similar to 1-10 pm in lateral sizes and a few hundred nanometers in thicknesses was mechanically treated using a ball-mill to intentionally introduce defect sites. h-BN was ball-milled for various tunes and subsequently was functionalized with a long alkyl chain amine via Lewis acid-base interactions between the amino groups and the boron atoms of h-BN to obtain soluble amine-attached nanosheet samples as the products. The functionalized h-ON nanosheet samples were characterized via various microscopic and spectroscopic techniques. The results strongly support a direct correlation between increasing defect site concentrations of the h-ON nanosheet samples and improved reaction efficiency with the amine. This suggests the enhanced reactivity of defect boron atoms in comparison to conjugated ones arm an unperturbed h-ON plane. NMR investigations provided the strongest evidence supporting the hypothesis that the amino groups reacted with the h-ON at specific defect sites induced by ball-milling. The mechanistic implications are discussed.