Black Phosphorus, a Rising Star 2D Nanomaterial in the Post-Graphene Era: Synthesis, Properties, Modifications, and Photocatalysis Applications.

Semiconductor photocatalysis, a sustainable and renewable technology, is deemed to be a new path to resolve environmental pollution and energy shortage. The development of effective photocatalysts, especially the metal-free photocatalysts, is a critical determinant of this technique. The recently emerged 2D material of black phosphorus with distinctive properties of tunable direct bandgap, ultrahigh charge mobility, fortified optical absorption, large specific surface area, and anisotropic structure has captured enormous attention since the first exfoliation of bulk black phosphorus into mono- or few layered phosphorene in 2014. In this article, the state-of-the-art preparation methods are first summarized for bulk black phosphorus, phosphorene, and black phosphorus quantum dot and then the fundamental structure and electronic and optical properties are analyzed to evaluate its feasibility as a metal-free photocatalyst. Various modifications on black phosphorus are also summarized to enhance its photocatalytic performance. Furthermore, the multifarious applications such as solar to energy conversion, organic removal, disinfection, nitrogen fixation, and photodynamic therapy are discussed and some of the future challenges and opportunities for black phosphorus research are proposed. This review reveals that the rising star of black phosphorus will be a multifunctional material in the postgraphene era.