A vapor-phase carbon-deposition route to efficient inorganic nanosheet-based electrodes

Efficient inorganic nanosheet-based electrode materials can be synthesized by the calcination of exfoliated Ti₅NbO₁₄ nanosheets under C₂H₂ flow. While the calcination in Ar atmosphere causes a phase transformation from layered Ti₅NbO₁₄ to TiO₂ and Nb₂O₅, employing C₂H₂ atmosphere leads to the maintenance of the original layered structure of Ti₅NbO₁₄ upon the heat-treatment, which is attributable to the stabilization of layered lattice by surface passivation by deposited carbon layer. The resulting carbon@titanoniobate materials show mesoporous house-of-cards-type stacking structure of 2D nanosheets. This carbon@titanoniobate material delivers large discharge capacity of ~320 mA h g⁻¹ with excellent cyclability and rate performance, which is much superior to that of carbon-free homologue. The present study clearly demonstrates that the heat-treatment under C₂H₂ flow provides a simple and effective route to high-performance inorganic nanosheet-based electrode materials.