Fabrication of hollow TiO₂ nanotubes via a simple gas-phase process using in-flight coating followed by heat treatment

As nanostructured materials with wide applicability, hollow TiO₂ nanotubes (HTNT) were fabricated via in-flight coating method. TiO₂ coating layers were deposited on the surface of carbon nanotubes (CNT) suspended in gas, and the resulting products were then heat-treated. Depending on the annealing process, products with various morphologies, including HTNT, were produced. Raman spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy analyses confirmed the absence of CNT in the HTNT. The obtained results will provide insigth for controlling hollow nanostructured materials for a wide range of applications in fields including photocatalysis, gas sensors, and solar cells.