Nanotubes from Oxide-Based Misfit Family: The Case of Calcium Cobalt Oxide

作者：Panchakarla Leela S; Lajaunie Luc; Ramasubramaniam Ashwin^*; Arenal Raul^*; Tenne Reshef^*

来源：ACS Nano, 2016, 10(6): 6248-6256.

DOI：10.1021/acsnano.6b02430

• oxide-based misfit layered compounds (MLCs)
• nanotubes
• EELS-STEM
• DFT

Misfit layered compounds (MLCs) have generated significant interest in recent years as potential thermoelectric materials. MLC nanotubes could reveal behavior that is entirely different from the bulk material. Recently, new chemical strategies were exploited for the synthesis of nanotubular forms of chalcogenide-based MLCs, which are promising candidates for thermoelectric materials. However, analogous synthesis of oxide-based MLC nanotubes has not been demonstrated until now. Here, we report a chemical strategy for synthesis of cobalt oxide-based misfit nanotubes. A combination of high resolution (scanning) transmission electron microscopy (including image simulations), spatially resolved electron energy-loss spectroscopy, electron diffraction, and density functional theory (DFT) calculations is used to discover the formation of a phase within these nanotubes that differs significantly from bulk calcium cobaltite MLCs. Furthermore, DFT calculations show that this phase is semiconducting with a band gap in excess of 1 eV, unlike bulk calcium cobaltite MLCs, which are known to be metallic. Through systematic experiments, we propose a formation mechanism for these nanotubes that could also apply more generally to realizing other oxide-based MLC nanotubes.

• 出版日期2016-6