Efficient photocatalytic activity of bismuth oxyhalides with preferentially oriented (210) facets under visible light (original) (raw)
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Korean Journal of Chemical Engineering, 2018
The main environmental problems associated with water body pollution are typically those caused by the discharge of untreated effluents released by various industries. Wastewater from the textile dye industry is itself a large contributor and contains a huge number of complex components, a wide spectrum of organic pollutants with high concentration of biochemical oxygen demand (BOD)/chemical oxygen demand (COD) and other toxic elements. One of several potential techniques to degrade such reactive dyes before being discharged to water bodies is photocatalysis, and bismuth-based photocatalysts are rapidly gaining popularity in this direction. Bismuth oxyhalides, BiOX (X=Cl, Br, I, F), as a group of ternary compound semiconductors (V-VI-VII), have been explored extensively for their photocatalytic activity due to their unique crystal lattice with special layered structure in pure as well as modified form. With suitable band gap and band edge positions, which are a required condition for efficient water breakup and high photon absorption, BiOCl scores over other oxyhalides. Photocatalytic activity depends on many factors such as synthesis method, morphology, size, illumination type, dye choice among others. This paper gives a critical review on bismuth oxyhalides as a family on various aspects of modifications such as doping (with unique and interesting metals as well), morphology and synthesis parameters, polymer and carbon assisted composites in order to further enhance the photocatalytic efficiency in UV/visible region of solar spectrum.
Frontiers in Chemistry
An important target of photoelectrocatalysis (PEC) technology is the development of semiconductor-based photoelectrodes capable of absorbing solar energy (visible light) and promoting oxidation and reduction reactions. Bismuth oxyhalide-based materials BiOX (X = Cl, Br, and I) meet these requirements. Their crystalline structure, optical and electronic properties, and photocatalytic activity under visible light mean that these materials can be coupled to other semiconductors to develop novel heterostructures for photoelectrochemical degradation systems. This review provides a general overview of controlled BiOX powder synthesis methods, and discusses the optical and structural features of BiOX-based materials, focusing on heterojunction photoanodes. In addition, it summarizes the most recent applications in this field, particularly photoelectrochemical performance, experimental conditions and degradation efficiencies reported for some organic pollutants (e.g., pharmaceuticals, organ...
AAS open research, 2022
Background: The removal of textile wastes is a priority due to their mutagenic and carcinogenic properties. In this study, bismuth oxyhalide was used in the removal of methylene blue (MB) which is a textile waste. The main objective of this study was to develop and investigate the applicability of a bismuth oxyhalide (BiOBr z I (1-z)) solid solutions in the photodegradation of MB under solar and ultraviolet (UV) light irradiation. Methods: Bismuth oxyhalide (BiOBr z I (1-z)) (0 ≤ z ≤ 1) materials were successfully prepared through the hydrothermal method. Brunauer-Emmett-Teller (BET), transmission electron microscope (TEM), X-ray diffractometer (XRD), and scanning electron microscope (SEM) were used to determine the surface area, microstructure, crystal structure, and morphology of the resultant products. The photocatalytic performance of BiOBr z I (1-z) materials was examined through methylene blue (MB) degradation under UV light and solar irradiation. Results: The XRD showed that BiOBr z I (1-z) materials crystallized into a tetragonal crystal structure with (102) peak slightly shifting to lower diffraction angle with an increase in the amount of iodide (I-). BiOBr 0.6 I 0.4 materials showed a point of zero charge of 5.29 and presented the highest photocatalytic activity in the removal of MB with 99% and 88% efficiency under solar and UV irradiation, respectively. The kinetics Open Peer Review Reviewer Status Invited Reviewers
Cogent Chemistry, 2015
BiOCl, BiOBr, and BiOI have been synthesized by wet chemical route using bismuth nitrate (Bi(NO3)3.5H2O) and potassium halides, KCl, KBr, and KI, using a mixture of de-ionized water and ethanol as the solvent. Synthesized samples were characterized by X-ray diffraction and high-resolution SEM to observe the crystalline phase and crystallite size. Effective surface areas of the synthesized samples were estimated by Brunauer-Emmett-Teller studies. Photoactive properties of these samples were studied under three types of light exposure conditions viz. UV light from mercury vapour lamp, natural sunlight, and visible radiations from a 100-W incandescent tungsten filament. Degradation of methyl orange (MO) in aqueous media was estimated spectrophotometerically in visible range from the area under the curve with a peak at 464 nm. Kinetic constant for degradation reaction was calculated assuming the pseudo-first-order degradation mechanism. It was revealed that all the three samples show excellent degradation of MO in UV exposure with BiOCl as the most efficient photocatalyst in these radiations. BiOBr shows highest photodegradation performance among the three samples under natural sunlight exposure. Overall performance of the three photocatalyst samples is much better than the popular titanium dioxide photocatalyst.
The Journal of Physical Chemistry C, 2012
In this study, a facile and effective method to modify the photocatalytic performance of a bismuth oxybromide (BiOBr) semiconductor through the fabrication of a heterojunction with a hydrated bismuth oxide (BHO) is reported. The new yBiOBr-(1 − y)BHO heterojunction, synthesized by a simple hydrothermal method, exhibits a high photocatalytic activity under visible light irradiation for the photodegradation of typical organic pollutants in water, such as Rhodamine B (RhB) and acetophenone (AP). Both the individual BiOBr and BHO components show very low photocatalytic efficiency. Furthermore, the unique photocatalytic performance of the new hybrid material was demonstrated through the uphill photocatalytic reaction that involves the oxidation of potassium iodide (KI) to triiodide. The remarkable photocatalytic activity of the coupled system is directly related to the effectual charge carrier separation due to the formation of the heterostructure. 0.9BiOBr-0.1BHO shows a higher photocatalytic activity as compared with other members of the same family, 0.8BiOCl-0.2BHO and 0.8BiOI-0.2BHO, which is directly ascribed to a synergistic effect of the energy bandgap structure and flow of charge carriers through the heterojunction, surface area, and light absorbance. In comparison with TiO 2 (Degussa P25), the new composite material demonstrated 10.7 times higher activity in removing aqueous RhB under visible light (λ ≥ 420 nm) irradiation. Study of the photocatalytic mechanism proves that the degradation of RhB under visible light irradiation over the as-prepared 0.9BiOBr-0.1BHO is mainly via a direct hole oxidation mechanism and superoxide oxidation pathways. The resulting yBiOBr-(1 − y)BHO composites exhibit high photocatalytic and thermal stabilities and are very promising photocatalysts for degradation of organic pollutants in water and for other applications.
Synthesis of bismuth oxyhalide (BiOBrzI(1-z)) solid solutions for photodegradation of methylene dye
AAS Open Research
Background: The removal of textile wastes is a priority due to their mutagenic and carcinogenic properties. In this study, bismuth oxyhalide was used in the removal of methylene blue (MB) which is a textile waste. The main objective of this study was to develop and investigate the applicability of a bismuth oxyhalide (BiOBrzI(1-z)) solid solutions in the photodegradation of MB under solar and ultraviolet (UV) light irradiation. Methods: Bismuth oxyhalide (BiOBrzI(1-z)) (0 ≤ z ≤ 1) materials were successfully prepared through the hydrothermal method. Brunauer-Emmett-Teller (BET), transmission electron microscope (TEM), X-ray diffractometer (XRD), and scanning electron microscope (SEM) were used to determine the surface area, microstructure, crystal structure, and morphology of the resultant products. The photocatalytic performance of BiOBrzI(1-z) materials was examined through methylene blue (MB) degradation under UV light and solar irradiation. Results: The XRD showed that BiOBrzI(...
DESALINATION AND WATER TREATMENT, 2023
BiOI/Bi 2 O 3 /MgO hetero-structured (B/B/M) was prepared by a hydrothermal method and then calcined at different temperatures (200°C, 300°C, 400°C, and 550°C) for 1 h. The efficiency of photocatalyst was tested on the photo-discoloration of a cationic dye (Rhodamine B (RhB)) under visible light (500 W tungsten lamp (Tungsram Trademark) that emits more than 400 nm) and compared to Bi 2 O 3 , TiO 2-P25 and BiOI as reference photocatalysts. The prepared samples were characterized by X-ray diffraction, Brunauer-Emmett-Teller, UV-Visible diffuse reflectance spectroscopy and scanning electron microscopy. In this new photocatalysts, three structures have been identified BiOI, Bi 2 O 3 , and MgO before and after heat treatment. Indeed, the sample prepared and calcined at 400°C/1 h show a good crystallinity and display microspheres porous in the form of cauliflower-like. Furthermore, the photocatalytic test of B/B/M-400 has shown efficiency on the photodegradation of RhB. Indeed, a total discoloration of 10 mg/L of RhB was achieved at 110 min.
Key Engineering Materials, 2017
Azo dyes are usually used in textile industry. However, they can cause water contamination, lead to water pollution, damage to aquatic lives and degenerate scenery due to their toxicity. These problems can be overcome by photocatalytic process in which the azo dyes are converted to CO2 and water. This research concentrates on effect of Bi2O3, BiOBr and BiOI contents on titanium dioxide substance (TiO2) for the photocatalytic process. In the study, photocatalysts were synthesized by sol-gel and wetness impregnation methods. They were studied in surface area by BET technique, chemical composition by FT-IR spectroscopy and optical properties by UV-DRS technique. Increase in bismuth content on TiO2 results in decreasing surface area. In FT-IR spectra, Ti-O-Ti stretching bands at 400-800 cm-1 were detected. The band gap energy of these photocatalysts is decreased when bismuth was doped. Since efficiency of CO2 and water conversion of the photocatalysts can be determined indirectly via de...
New efficient visible light photocatalyst based on heterojunction of BiOCl–bismuth oxyhydrate
Applied Catalysis A: General, 2012
A novel active photocatalyst, which is a heteroconjuction of a bismuth oxyhydrate and BiOCl, has been synthesized by a simple hydrothermal method. The photocatalytic activity of the new material was measured in the degradation of Rhodamine B (RhB) and Acetophenone (AP) and in the photocatalytic oxidation of iodide in water under UV-vis and visible light irradiations respectively. The heterojunction between bismuth oxyhydrate and BiOCl provided exceptional photocatalytic activity, whereas both the individual bismuth oxyhydrate and BiOCl showed a negligible efficiency. Compared to Degussa P25, the new composite material demonstrated 5 times higher activity in removing aqueous RhB under visible light ( ≥ 420 nm) irradiation. The chemical composition and crystal structure were investigated using powder X-ray diffraction, scanning and transmission electron microscopy, and thermal methods. The preliminary study has revealed the bismuth oxyhydrate has tetragonal crystal structure with unit cell parameters a = b = 5.674Å, c = 10.353Å, unit cell volume V = 333.3Å 3 and possible P4/mmm (No. 123) space group. Temperature behavior of new photocatalyst has been investigated. It was found that at heating to 550 • C for 45 min the new phase transforms into well-known monoclinic Bi 2 O 3 .
2020
BiOI, BiOCl, and their composites with different molar ratios have been synthesized and tested for photocatalytic application, using methyl orange as model pollutant, and three various LED light sources. Adsorption capacity of BiOI highly exceeds that of BiOCl. The composite having 80:20 molar ratio of BiOI:BiOCl showed similar adsorption capacity than BiOI, and the best photocatalytic activity: about three times higher than BiOI and nine times higher than BiOCl. Methyl orange effectively transformed under visible light radiation, but with lower rate than under UV radiation. HPLC-MS measurements proved that the transformation of methyl orange is initiated with a demethylation. Effect of methanol as HO scavenger, and 1-4 benzoquinone proved that, the transformation of dye is initiated via direct charge transfer, and/or via photosensitization. Hydroxyl radical has no contribution to the transformation. The change of photocatalytic efficiency was followed during three cycles. After the first one, the transformation rate of methyl orange decreased, but there was no significant difference between the rates determined in the case of the second and third cycles. Ecotoxicity measurements confirmed that no toxic substances were dissolved from the catalyst under radiation, but the toxicity of methyl orange solution significantly increased during the treatment.