Electrochemical Exfoliation of Layered Black Phosphorus into Phosphorene.

Among 2D materials that recently have attracted enormous interest, black phosphorus (BP) is gaining a rising popularity due to its tunable band-gap structure, which is strongly correlated to the thickness and can enable its use in optoelectronic and electronic applications. It is therefore important to provide a facile and scalable methodology to prepare single or few-layer BP nanosheets. We propose herein a simple and fast top-down method to exfoliate a BP crystal into nanosheets of reduced thickness by using electrochemistry. The application of an anodic potential to the crystal in an acidic aqueous solution allows control over the exfoliation efficiency and quality of the nanosheets produced. X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and scanning transmission electron microscopy (STEM) have been applied to fully characterize the exfoliated material, which presented significantly reduced layer thickness compared to the starting bulk material.