Formation of black phosphorus quantum dots via shock-induced phase transformation

Black phosphorus quantum dots (BPQDs) have recently obtained great attention owing to their outstanding properties, such as high hole mobility, quantum confinement effect, and edge effect. At present, several methods have been applied to prepare BPQDs using black phosphorus as precursor. In this study, BPQDs are obtained via shock-induced phase transformation using ball-milled red phosphorus nanopowder as precursor. The red phosphorus powder was ball-milled and shocked to induce phase transformation at transient high pressure and temperature. Multiple techniques are applied to characterize the recovered samples, including x-ray diffraction, Raman spectroscopy, transmission electron microscopy, and atomic force microscope. The characterization results demonstrate that the majority of recovered sample is BPQDs with a lateral size of 2-10 nm and a thickness of 0.9-2 nm. In addition, the formation mechanism of BPQDs under shock treatment was carefully analyzed, consisting of phase transformation induced by shock loading and exfoliation by tensile and shear effects. Furthermore, this study also confirms that the micromorphology of precursor is critical to the formation of BPQDs. This research provides an efficient one-step path to prepare BPQDs using ball-milled red phosphorus nanopowder as precursor.