Covalent carbene modification of 2D black phosphorus

Abstract

Black phosphorus (BP) has attracted an ever-growing interest due to its unique anisotropic two-dimensional structure, impressive photoelectronic properties and attractive application potential. However, the tools for bandgap engineering and passivation via covalent modification of BP nanosheets remain limited to diazonium salt and nucleophilic addition methods, so that developing new modification strategies for BP nanosheets is crucial to explore its physical and chemical properties and enrich the toolbox for functionalization. Herein, we report the covalent modification of liquid-phase exfoliated BP nanosheets based on a rational analysis of BP structure. The modification of BP is achieved via carbene, a highly reactive organic mediate. The carbene modification improves the solubility and stability of BP nanosheets. Detailed microscopic and spectroscopic characterizations including infrared spectra, Raman spectra, X-ray photoelectron spectra, SEM and TEM were conducted to provide insights for the reaction. The proof of the existence of covalent bonds between BP nanosheets and organic moieties confirms the successful modification. Moreover, theoretical calculations were conducted to unveil the reaction mechanism of the two different types of bonds and the chemical property of two-dimensional BP.