Visible-light-driven NaTaO3−xNx catalyst prepared by a hydrothermal process

NaTaO_3−xN_x catalyst has been successfully synthesized from N-doped Ta₂O₅ precursors by a simple hydrothermal process. The as-prepared samples were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and diffuse reflectance spectroscopy. Density functional theory calculations suggested that the valence band of the catalysts was composed of the hybrid O 2p and N 2p orbitals, and the visible-light sensitivity is due to the narrowing of the band gap by mixing N 2p and O 2p states. NaTaO_3−xN_x catalyst could decompose the gaseous formaldehyde under the visible-light irradiation (λ > 400 nm), and its photocatalytic activity depended on N dopant concentration. NaTaO_2.943N_0.047 showed the highest photoactivity for the formaldehyde photodegradation.