Two-dimensional crystals: Phosphorus joins the family

Abstract

Graphene was first isolated by exfoliating single layers from a graphite crystal using Scotch tape. This method was later applied to other materials with layered structures, creating a family of atomically layered materials that includes insulators such as hexagonal boron nitride, metals such as NbSe[subscript 2], and semiconductors such as MoS[subscript 2] and WSe[subscript 2]. All of these materials had been studied for decades in bulk form, but their exfoliated, two-dimensional form gave them new life and properties. Writing in Nature Nanotechnology, Xian Hui Chen, Yuanbo Zhang and co-workers have now similarly brought black phosphorus back to the spotlight, which is the most stable and least reactive form of elemental phosphorus, and was discovered in bulk form 100 years ago.