A Novel Strategy for Liquid Exfoliation of Ultrathin Black Phosphorus Nanosheets.

As an emerging two-dimensional layered material, black phosphorus nanosheets show unparalleled optical and electronic properties. Although black phosphorus nanosheets have attracted much attention in the photoelectric field, their appli-cations in biomedical field were still limited due to their poor biocompatibility of current synthesis strategies. Herein, we propose a novel synthetic strategy for black phosphorus nanosheets that rely on Tween 20-assisted liquid exfoliation and post-processing in deoxygenated water. Microscopic and spectroscopic analysis suggested that the produced black phos-phorus nanosheets dispersions exhibited good stability and higher yield compared with other currently prepared methods. Because of their ultrahigh exfoliation efficiency, the black phosphorus flakes present few-layer and even monolayer, which are thinner than the most dispersions of black phosphorus. Thus, this method enables mass-production of high-quality few-layer black phosphorus with high biocompatibility, and has the potential to be directly used in the biological field.