Nanotube-terminated zigzag edges of phosphorene formed by self-rolling reconstruction

Edge atomic configuration often plays an important role in dictating the properties of finite-sized two-dimensional (2D) materials. By performing ab initio calculations, we identify a highly stable zigzag edge reconstruction of phosphorene among all the considered edges. Surprisingly, this highly stable edge exhibits a novel nanotube-like structure, which is topologically distinctively different from any previously reported edge reconstruction. We further show that this new edge type can form easily, with an energy barrier of only 0.234 eV. It may be the dominant edge type at room temperature in vacuum condition or even under low hydrogen gas pressure. The calculated band structure reveals the reconstruction edge possesses a 1.23 eV bandgap. It is expected that this newly found edge structure may spark extensive studies to the various properties of finite-size phosphorene, stimulate more studies in uncovering other novel edge types, and further exploring their practical applications.