High photocatalytic performance of BiOI/Bi2WO6 toward toluene and Reactive Brilliant Red

• Published in: Applied surface science 2013-01, Vol.264, p.581-588
• Main Authors: Li, Huiquan, Cui, Yumin, Hong, Wenshan
• Format: Article
• Language: English
• Subjects: Bi2WO6; BiOI; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Photocatalysis; Physics; Reactive Brilliant Red; Toluene
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2012.10.068

When BiOI/Bi2WO6 catalyst was exposed to UV or visible light, the electrons in the valence band of Bi2WO6 would be excited into the conduction band and then injected into the more positive conduction band of BiOI. Therefore, the photoelectrons were generated from Bi2WO6 and transferred across the interface between BiOI and Bi2WO6 to the surface of BiOI, leaving the photogenerated holes in the valence band of Bi2WO6. In this way, the photoinduced electron–hole pairs were effectively separated. [Display omitted] ► BiOI sensitized Bi2WO6 catalysts were successfully prepared by a facile method. ► The 13.2% BiOI/Bi2WO6 catalyst exhibits higher photoactivities than P25. ► A possible transfer process of photogenerated carriers was proposed. BiOI sensitized nano-Bi2WO6 photocatalysts with different BiOI contents were successfully synthesized by a facile deposition method at room temperature, and characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) high-resolution transmission electron microscopy (HR-TEM), photoluminescence (PL) spectra, UV–vis diffuse reflection spectroscopy (UV–vis DRS) and Brunauer–Emmett–Teller (BET) surface area measurements. The photocatalytic activity of BiOI/Bi2WO6 was evaluated by the photo-degradation of Reactive Brilliant Red (X-3B) in suspended solution and toluene in gas phase. It has been shown that the BiOI/Bi2WO6 catalysts exhibit a coexistence of both tetragonal BiOI and orthorhombic Bi2WO6 phases. With increasing BiOI content, the absorption intensity of BiOI/Bi2WO6 catalysts increases in the 380–600nm region and the absorption edge shifts significantly to longer wavelengths as compared to pure Bi2WO6. The 13.2% BiOI/Bi2WO6 catalyst exhibits obviously higher UV and visible light photocatalytic activities than commercial P25, pure Bi2WO6 and BiOI, for the photodegradation of toluene and X-3B. The remarkably enhanced photocatalytic activities can be attributed to the fact that the proper BiOI sensitized nano-Bi2WO6 increase its BET surface area, decrease band-gap energy, enhance absorption in the 380–600nm region and inhibit the recombination of photo-induced carriers.