Gram-scale preparation of black phosphorus nanosheets via shock-induced phase transformation

In this study, well-crystallized black phosphorus nanosheets are obtained via shock-induced phase transformation. Red phosphorus powder is filled in a sample container and subjected to high shock pressure and temperature using a shock-driven flyer. Moreover, flyer impact velocity is adjusted to investigate the influence of shock pressure and temperature on the phase transformation of red phosphorus. The recovered black samples are characterized via multiple techniques, such as X-ray diffraction, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy and atomic force microscopy. The characteristic results demonstrate the presence of black phosphorus nanosheets with a lateral size of 0.5-20 mu m and a thickness of 1.5-50 nm. Moreover, the results also confirm the critical influence of the shock pressure on the micromorphology of the recovered samples. The increase of shock pressure thickens the formed black phosphorus nanosheets and decreases their lateral size. In addition, the formation mechanism of black phosphorus nanosheets by shock-induced phase transformation of red phosphorus is carefully analyzed. This research provides a new method to prepare gram-scale black phosphorous nanosheets through shock treatment for the first time.