Structure-search-revealed edge reconstruction in two-dimensional materials: The case of phosphorene nanoribbons

Abstract

The edge structures of two-dimensional materials are important for the property control of corresponding nanoribbons, but possible edge reconstructions are difficult to resolve. Taking phosphorene nanoribbons as an example, we have employed the structure-searching program IM2ODE to discover new structures for both zigzag and armchair edges of bare phosphorene nanoribbons. The edge atoms of these low-energy nanoribbons are generally 3-fold coordinated, and the edge energies are significantly lower than those directly cut from the monolayer. Moreover, we can build low-energy sinuous edges along the diagonal direction based on the bonding features of phosphorus atoms. Further electronic structure studies also reveal that zigzag phosphorene nanoribbons undergo cell doubling and metal-insulator transition similar to Peierls distortion, indicating that the edges experience self-passivation and become stabilized. As similar edge reconstructions can exist in many other two-dimensional materials and it may be difficult to construct the edges by hand, our structure-searching approach provides reliable insights and certain rules can be discovered to elucidate various structure reconstructions.