From two-dimensional nano-sheets to roll-up structures: expanding the family of nanoscroll.

The carbon nanoscroll (CNS), a spiral structure rolled up from a flat graphene sheet, has attracted significant attention due to its large surface area and broad electrochemical window. Despite the rapid emergence of many new two-dimensional (2D) materials, studies on nanoscrolls beyond CNS, however, remain limited. In this work, we combine first-principles calculations and theoretical analyses to determine the stable configuration of nanoscrolls constructed from several 2D materials, including graphene, h-BN, MoS, graphyne, phosphorene, and graphene oxide. Our study shows that the inner radius of these nanoscrolls ranges from 0.36-2.3 nm, significantly expanding that of CNS (about 1.2 nm). In addition, it is shown that the difference between the inner and outer pressures of nanoscrolls can be used to tune their core sizes. Furthermore, the effect of interlayer friction is found to be significant and may play a dominant role in determining the core sizes. The present study not only expands the nanoscroll family, but also enriches the understanding of nanoscrolls in terms of the effects of pressure and friction, thus widening the application range of nanoscrolls as nano-actuators, ion/water channels, nano-sensors, and hydrogen/energy storage devices, etc.