Synthesis of black phosphorus and its applications

2D and layered materials have attracted tremendous research interest due to their various exciting properties and potential for revealing intriguing novel phenomena. Black phosphorus, rediscovered in 2014, has been the focus of rapidly expanding research activities because of its unique crystalline symmetries, widely tunable band gap, strong in-plane anisotropy and high carrier mobility, making it at the center of numerous fundamental investigations and practical applications. Recently, a series of breakthrough experiments on the growth of high-crystalline black phosphorus films, the revelation of novel physical phenomena, and the innovative concepts of new electronic and photonic device have triggered great excitement within the scientific community. This review provides a comprehensive exploration of black phosphorus, covering its crystal structure, phase transition process, unique physical properties, and diverse synthesis methods (both bottom-up and top-down approaches, especially the methods of growing large-scale and high-crystalline products). Furthermore, it discusses recent advancements of black phosphorus in various applications such as transistors, photodetectors, energy storage and conversion, biomedicine, and biosensing. We conclude by addressing current challenges of black phosphorus and offering perspectives to guide future research in this burgeoning field.