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

•The first synthesis of carbon@titanoniobate nanosheets with mesoporous structure.•Enhancement of electrode activity of titanoniobate nanosheet upon carbon deposition.•Usefulness of C2H2 treatment in exploring efficient 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.