Stable CoO2 Nanoscrolls with Outstanding Electrical Properties

Layered CoO₂ is of great interest for its promising properties but is meta-stable in its bulk form. CoO₂ is synthesized by converting the quasi-1D crystal structure of bulk Ca₃Co₂O₆ via a hydrothermal treatment. The resulting nanostructures are predominantly nanoscrolls with very thin walls, which exhibit long-term stability. A detailed structural investigation reveals that the CoO₂ is found to crystallize in monoclinic form, similar to the related CaCoO₂-CoO₂ misfit structure. Individual nanoscrolls are characterized electrically and show a p-type semiconducting nature with a high current-carrying capacity of 4·10⁵ A cm⁻² and an extremely high breakdown voltage of up to 270 kV cm⁻¹. The results demonstrate the possibility to stabilize meta-stable materials in low-dimensional forms and a promising application of the nanoscrolls as interconnect in high-voltage electronic circuitry.