BiOX (X = Cl, Br, I) photocatalysts prepared using NaBiO3 as the Bi source: Characterization and catalytic performance

Abstract

The Bismuth oxyhalides, crystalline BiOX (X = Cl, Br, I) were prepared via a facile method, using NaBiO 3 25 and HX aqueous solutions as the raw materials for the first time. The systematic microstructure and opti-26 cal property characterizations of the BiOX photocatalysts demonstrated the reliability of this new and 27 facile preparation approach. The photocatalytic activity on the degradation of typical phenolic endocrine 28 disrupting chemicals over BiOX and P25 were evaluated under Xenon-light irradiation and the initial 29 photocatalytic mechanism was discussed based on the band edge potential analysis. 30 Ó 2009 Published by Elsevier B.V. 31 65 4f 5/2 , Bi 4f 7/2 , respectively. The peaks were centered at 165.1 and 66 159.8 eV in the BiOX samples corresponding to the binding energy 67 of Bi 4f 5/2 and Bi 4f 7/2 , demonstrating that the main chemical states 68 of Bismuth element in the samples were tri-valence [8]. The results 69 from the XPS and XRD demonstrate that there were unreduced 70 Bi 2 O 5 (V) phases in the samples. 71 The sheet-morphology of BiOCl, BiOBr and BiOI samples was ob-72 served on Field Emission Gun-Scanning Electronic Microscope 73 (FEG-SEM). Meanwhile, the Energy Dispersive X-ray analysis 74 (EDX) results indicated that Bi, O and X element from the crystals 75 were in stoichiometric amount. The Bright-Field Transmittance 76 Electronic Microscopy (BF-TEM) images of BiOX series crystals 77 were recorded by using a small objective aperture that selected 78 only the (0 0 0) central transmitted beam, showing that the parti-79 cle sizes of BiOX were around 690 nm, 650 nm and 120 nm, respec-80 tively. Such results were in accordance with the FEG-SEM results. 81 The particles were found to have single crystalline feature of the 82 BiOX samples, shown by electron diffraction patterns and addition-83 ally proved by high-resolution lattice imaging of individual

Photocatalytic properties of hierarchical BiOXs obtained via an ethanol-assisted solvothermal process

“…7a), indicating that the BiOBr is an excellent visible − light-response photocatalyst, as reported earlier. Again, no degradation of SA is observed in the BiOI system under either visible-light and UV irradiation, which is different from the results in previous reports (Chang et al, 2010;Qin et al, 2013;Zhang et al, 2008b), where it was reported that BiOI had the highest activity among BiOXs. Considering the narrow band gap and strong visible light absorption of BiOI, its inactivity in photocatalytic degradation is somewhat striking in our study.…”

“…Since the most famous wide-band-gap (3.2 eV) photocatalyst TiO 2 cannot utilize sun light efficiently, BiOX semiconductors have attracted much attention as a class of promising photocatalysts due to their special structural and optical properties, with band gaps of approximately 3.2, 2.6 and 1.7 eV for BiOCl, BiOBr and BiOI powders (Chang et al, 2010;Qin et al, 2013;Zhang et al, 2008b), respectively, and can be excited by UV and/or visible light.…”

“…However, the activities reported are rather contradictory in the literature, and are markedly dependent on preparation conditions. For example, using NaBiO 3 and HX (X_Cl, Br, I) aqueous solutions as raw materials, sheet-like BiOXs were obtained in a previous study, among which BiOI exhibited the highest photocatalytic activity under Xenon-lamp irradiation for the degradation of typical phenolic EDCs, such as 4-nonylphenol (4-NP), 4-t-octylphenol (4-t-OP), sodium pentachlorophenate (PCP-Na) and bisphenol A (BPA) (Chang et al, 2010). When BiOXs were synthesized with Bi(NO 3 ) 3 ·5H 2 O and KX as raw materials in an aqueous solution at pH 1.96, BiOI was also observed to be more active than BiOBr under visible light irradiation (λ > 400 nm) toward MO (Cao et al, 2013).…”

Synthesis and Characterization of 1-D BiSI and 2-D BiOI Nanostructures

“…Kumar et al employed a gel technique to obtain 5 mm long BiSI single crystals. 13 On the other hand, BiOI (the same V-VI-VII class compound) has widely been studied in recent years, [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] especially because of a high catalytic activity in the visible region. BiOI has been reported to show a high photocatalytic activity for photodegradation of an organic dye under visible light irradiation.…”

Visible-light photocatalytic activity and mechanism of novel AgBr/BiOBr prepared by deposition-precipitation

“…Various synthesis methods leading to BiOX have been reported, such as hydrothermal [15][16][17][18], transformation from NaBiO 3 [19], hydrolysis [20], homogenous deposition [21] and reverse microemulsions [22], which displayed different photoactivities of BiOX. Homogenous deposition is a simple way for the preparation of BiOX that has a plate structure, with high surface area, which facilities the adsorption of dyes and photocatalytic processes.…”