Vertically aligned, double-sided, and self-supported 3D WO3 nanocolumn bundles for low-temperature gas sensing

A three-dimensional (3D) hierarchical structure consisting of vertically aligned, double-sided, and self-supported WO₃ nanocolumn bundles has been successfully synthesized via acid-assisted (HCl) hydrothermal process, which proves to be an excellent NO₂-sensing material at a low operating temperature.