Electronic behavior and structural robustness of recently synthesized CoO2 nanoscrolls

Abstract

Cobalt dioxide (CoO₂) is a metastable material in its two-dimensional (2D) form. However, it can be stabilized in the form of nanoscrolls, which have been recently synthesized and shown to display long-term stability and remarkable electronic properties. In this work, we have investigated through Density Functional Tight-Binding simulations their structural and electronic properties. Nanoscrolls with 1.5, 2, and 3 turns were considered, exhibiting increasing stability due to van der Waals interactions. The analysis of the electronic structure confirms the metallic nature of these systems, and the charge density results emphasize the role of oxygen atoms in charge displacement, with the Highest Occupied Crystal Orbital (HOCO) and the Lowest Unoccupied Crystal Orbital (LUCO) spatially localized at opposite edges due to curvature effects. Molecular dynamics simulations demonstrate that the nanoscrolls remain stable up to 600 K. The optimized interlayer distance of 0.46 nm and the slight structural flattening observed in the simulations are both consistent with experimental reports. These results provide a coherent description of the stability, charge distribution, and metallic character of CoO₂ nanoscrolls.