Preparations, properties and applications of low-dimensional black phosphorus

Black phosphorus (BP) with a layered structure is the most stable allotrope of phosphorus, which was first prepared under high pressure in 1914. Since the development of a field-effect transistor with BP in 2014, BP has drawn interest, exhibiting numerous superior properties, such as distinct pleated structures in layers, an adjustable direct band gap, high carrier mobility, and many interesting in-layer anisotropies. This review summarizes the latest preparation techniques, properties, and applications of low-dimensional BP. Methods for the fabrication of two-dimensional BP include mechanical exfoliation, electrochemical assistance, and liquid exfoliation. The last method can also produce BPQDs by changing the process. In numerous excellent physical properties of BP, this review emphasizes its distinct anisotropy, including mechanical, thermally conductive, optical anisotropy, and so on. The potential uses of low-dimensional BP, involving field-effect transistors, photodetectors, catalysts, as well as photothermal therapeutic agents, are introduced in detail. The last application listed is closely associated with the health of human beings. To improve the stability of BP, its degradation mechanism with several fruitful protection methods is elaborated. Finally, the shortcomings in current research are discussed, and suggestions and prospects are proposed for the future research on low-dimensional BP.