Efficient photocatalytic removal of nitric oxide with hydrothermal synthesized Na_0.5Bi_0.5TiO₃ nanotubes

Highlights: • Na_0.5Bi_0.5TiO₃ nanotubes were prepared via a facile hydrothermal route. • The Na_0.5Bi_0.5TiO₃ nanotubes exhibited superior photocatalytic performances for the removal of nitric oxide. • The Na_0.5Bi_0.5TiO₃ nanotubes show potential for indoor and outdoor air purification. - Abstract: In this study, Na_0.5Bi_0.5TiO₃ nanotubes were synthesized with a facile hydrothermal method using TiO₂ P25 (Degussa) and bismuth citrate (BiC₅H₆O₇) as precursors in concentrated NaOH and ammonia alkali solution. The samples were systematically characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The as-prepared Na_0.5Bi_0.5TiO₃ nanotubes exhibited superior activity for photocatalytic removal of gaseous nitric oxide (NO) over TiO₂ P25 (Degussa) under simulated solar-light irradiation, the NO removal rate can reach as high as ca. 200 ppb·min⁻¹ over the Na_0.5Bi_0.5TiO₃ nanotubes in a continuous reactor with an initial NO concentration of 400 ppb. The intrinsic hollow-nanotube structure of the Na_0.5Bi_0.5TiO₃ photocatalysts contributes to its superior activity under simulated solar light. This work provides a facile route to prepare Na_0.5Bi_0.5TiO₃ nanotubes and suggests that the Na_0.5Bi_0.5TiO₃ nanotubes are ideal candidates for efficient removal of nitric oxide in indoor/outdoor air