Coupling with a narrow-band-gap semiconductor for the enhancement of visible-light photocatalytic activity: preparation of Bi2OxS3−x/Nb6O17 and application to the degradation of methyl orange

Abstract

A series of 2D sheet Bi₂O_xS_3−x/Nb₆O₁₇ (Bi/Nb) heterostructure photocatalysts were synthesized through a facile hydrothermal vulcanization method between Bi³⁺ exchanged K₄Nb₆O₁₇ and thiourea (NH₂CSNH₂). XRD results confirm that the heterostructures were composed of Bi₂O_xS_3−x and Nb₆O₁₇. HRTEM indicates that Bi₂O_xS_3−x was successfully intercalated into layers of K₄Nb₆O₁₇. Such large interfacial contacts can be beneficial to the transfer and separation of photogenerated charge carriers. Thus the composites exhibit good photocatalytic performance for the degradation of methyl orange (MO) under visible light irradiation (λ > 400 nm), which is superior to that of both precursors, pure Bi₂S₃ and K₄Nb₆O₁₇. Radical capture tests reveal that photogenerated holes h⁺ and ˙O₂⁻ play important roles in the photodegradation of MO. And based on the UV-visible diffuse reflectance spectra (DRS) and the band gap of the semiconductors, the mechanism of the enhanced visible light photocatalytic activity of these composites has been proposed.