Ultrasonic Spray Pyrolysis Synthesis of Porous Bi₂WO₆ Microspheres and Their Visible-Light-Induced Photocatalytic Removal of NO

Abstract

In this study, porous Bi2WO6 microsphere photocatalysts were obtained via the ultrasonic spray pyrolysis method using bismuth citrate and tungstic acid as precursors in basic aqueous solution. The characteristics of the resulting samples were investigated in detail by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, N2 adsorption/desorption, X-ray photoelectron spectroscopy, and UV−vis diffuse reflectance spectroscopy. The resulting porous Bi2WO6 microsphere was of high crystallinity, which means fewer traps and stronger photocatalytic activity. The band-gap energy of Bi2WO6 microspheres estimated from the (αhν)2 versus photon energy (hν) plots was 2.92 eV. The formation of the porous structure in the as-prepared microspheres can be ascribed to the existence of citrate anions and in situ generated carbon residues that can serve as capping agents and templates, respectively, during the synthesis processes. It was found that the synthesis temperature was an important parameter controlling the morphology of the Bi2WO6 microspheres. As compared with the bulk Bi2WO6 sample, the resulting porous Bi2WO6 microspheres demonstrated superior photocatalytic activities on the removal of NO under either visible light or simulated solar light irradiation. The highest NO removal rates were 110 and 27 ppb/min for the porous Bi2WO6 sample under solar light and visible light (λ > 400 nm) irradiation, respectively. On the basis of the analysis of the characterization and experimental observations, a possible mechanism on the formation of porous Bi2WO6 microspheres was also proposed.

Photocatalytic removal of nitric oxide by Bi2Mo3O12 prepared by co-precipitation method

“…To the best of our knowledge no study has been reported on the photocatalytic removal of NO x using Bi 2 Mo 3 O 12 as photocatalyst. However, the isostructural tungstate phase of Bi 2 MoO 6 , with chemical formula Bi 2 WO 6 was reported for NO removal under visible and solar light irradiation [16]. In the current work, the photocatalytic activity of Bi 2 Mo 3 O 12 oxide was tested under UVA irradiation for NO removal from air under different experimental conditions.…”

Low-dimensional nanostructured photocatalysts

“…Numerous methods have been employed to fabricate 0-D PCs including coprecipitation or chemical precipitation, hydrothermal/solvothermal process [19,20], sol-gel, solid state reaction (SSR), spray pyrolysis [21][22][23], combustion [24,25], reversemicroemulsion [26,27], and modified approaches based on them. The morphology and performance of photocatalyst crystal intensely depend on the synthesis 3 .…”

Bi2WO6 micro/nano-structures: Synthesis, modifications and visible-light-driven photocatalytic applications

“…40 nm. In addition, by the ultrasonic spray pyrolysis (USP) method instead of hydrothermal process, Lee group obtained Bi 2 WO 6 porous microspheres via using bismuth citrate and tungsten acid as precursors in basic aqueous solution [61].…”