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Evaluation of the reaction mechanism for photocatalytic degradation of organic pollutants with MIL-88A/BiOI structure under visible light irradiation
摘要： In this study, we synthesized novel visible light photocatalyst MIL-88A/BiOI using depositing BiOI particles on the surface of a metal–organic framework (MIL-88A). Photocatalytic application of binary composite MIL-88A/BiOI was obtained by discoloration of Methylene Blue (MB) and Acid Blue 92 (AB92) in aqueous solution under visible light source. The photodegradation experiments for treating organic dyes show that the MIL-88A/BiOI heterojunction structure possess a higher rate for decomposition of dyes due to the decreased aggregation of the BiOI nanoparticles, effective charge carrier separation and the synergistic effect between MIL-88A and BiOI samples as a heterojunction. Also, the MIL-88A/BiOI structure shows better photocatalytic degradation performance for anionic dyes (AB92) than for a cationic dye (MB). It was further found that ?OH and ?O2? radicals were the most important species responsible for the photodegradation test.
关键词： Visible light-driven,Photocatalyst,BiOI,MIL-88A metal organic framework
更新于2025-09-10 09:29:36
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Self-sacrifice transformation for fabrication of type-I and type-II heterojunctions in hierarchical BixOyIz/g-C3N4 for efficient visible-light photocatalysis
摘要： Construction of semiconductor heterojunction with hierarchical architectures is highly effective for improving photocatalytic performance. Different heterojunction types with distinct mechanisms lead to different photocatalytic activity enhancement level, and thus the control on heterojunction type is meaningful. Herein, we achieve the fabrication of a series of different types of hierarchical heterojunctions in BixOyIz/g-C3N4, namely, g-C3N4/BiOI, g-C3N4/Bi4O5I2, and g-C3N4/Bi5O7I. g-C3N4/BiOI is prepared by a direct precipitation method, and g-C3N4/Bi4O5I2 and g-C3N4/Bi5O7I are obtained by in situ calcination transformation of g-C3N4/BiOI at different temperature. Among them, g-C3N4/BiOI and g-C3N4/Bi4O5I2 are type-I heterojunction, and g-C3N4/Bi5O7I belongs to type-II heterojunction. The photocatalyitc activity is surveyed by decomposition of diverse industrial contaminants, including methyl orange, bisphenol A and tetracycline hydrochloride under visible light irradiation (λ > 420 nm). It is found that g-C3N4/Bi5O7I shows largely enhanced photodegradation performance compared to g-C3N4/BiOI and g-C3N4/Bi4O5I2. The much higher photocatalytic activity of g-C3N4/Bi5O7I is attributed to the enhanced specific surface area, more efficient charge separation and surface transfer efficiency and increased density of charge carriers owing to the formation of type-II heterojunction. The study provides a reference for in situ fabrication of hierarchical photocatalysts with diverse heterojunction types for optimizing photocatalytic activity.
关键词： g-C3N4,Bi5O7I,heterojunction,BiOI,Bi4O5I2
更新于2025-09-10 09:29:36
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Decoration of SrTiO3 nanofibers by BiOI for photocatalytic methyl orange degradation under visible light irradiation
摘要： BiOI decorated electrospun SrTiO3 nanofibers (BE) with a spiky club structure were fabricated using a rapid microwave-assisted solvothermal method. The exposed (102) plane of BiOI preferentially coupled with the electrospun SrTiO3 fibers aiming to achieve charge neutrality. XRD analysis demonstrated that a BE composite coupled with an optimal content of BiOI exhibited few crystal imperfections. The resulting BE samples showed a higher degradation efficiency towards methyl orange dye under visible light irradiation (λ > 400 nm) compared to the individual BiOI and SrTiO3. The BE composite possessed a high degradation rate of 0.015 (kapp, min–1) and a normalized rate constant of 2.46 × 10–3 (kapp/surface area), which was 7.7 and 1120 times higher than those of BiOI and SrTiO3 alone, and a degradation level over 94.6% within 3 h of irradiation under visible light. The high photocatalytic activity could be attributed to the heterostructure formation, p-n junction at the BE interface, high contact between water and dye molecules with the BiOI covered surface, and extended visible light absorption. This work provides an effective approach to produce BE nanofibers for dealing with methyl orange dye and proves that BE composites have the potential to serve as visible-light-driven photocatalysts.
关键词： Visible light irradiation,Photocatalyst,SrTiO3,BiOI,Nanofiber
更新于2025-09-09 09:28:46
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Microwave-assisted preparation and enhanced photocatalytic activity of Bi2WO6/BiOI heterojunction for organic pollutants degradation under visible-light irradiation
摘要： In this research, we adopted morphology control and constructing p-n heterojunction to boost the photocatalytic performance of BiOI. BiOI with three morphologies (nanoplate, micro-flower, microsphere) was fabricated via a wet-chemical method at room temperature using different solvents. And Bi2WO6/BiOI microspheres were successfully prepared by a microwave-assisted synthetic method. The as-synthesized samples were characterized by X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), Transmission Electron Microscopy (TEM), Energy Dispersive Spectroscopy (EDS) and High-resolution Transmission Electron Microscopy (HRTEM). The results of photo-degradation experiment demonstrated that BiOI-3 and BWOI-3 show high photocatalytic performance towards methyl orange (MO) and bisphenol A (BPA) degradation due to the high specific surface area, synergistic effect between p-type BiOI and n-type Bi2WO6 and high separation efficiency of electron-hole pairs, which is verified by Brunauer-Emmett-Teller (BET), Photocurrent (PC) and Electrochemical Impedance Spectroscopy (EIS) analysis. Moreover, the repeated photocatalytic experiment was carried out by using MO as the representative organic pollutant, manifesting the good durability of the sample.
关键词： Microwave-assisted,Heterojunction,Bi2WO6,Photocatalytic activity,BiOI
更新于2025-09-09 09:28:46
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Recoverable magnetic CoFe2O4/BiOI nanofibers for efficient visible light photocatalysis
摘要： A facile methodology for fabricating novel magnetic fibrous visible light photocatalysts CoFe2O4/BiOI (CFO/BiOI) is presented. The fabrication procedure involves production of electrospun CoFe2O4 nanofibers and subsequent controllable decoration of BiOI nanoplates by both the successive ionic layer adsorption and reaction (SILAR) and solvothermal methods on CoFe2O4 nanofiber surface. The BiOI nanoplates on the fiber surface obtained by two methods are highly crystallized with lamellae morphology. The resulting CFO/BiOI fibers exhibit strongly magnetic response to external magnetic field and can be quickly collected. All the CFO/BiOI fiber samples exhibit excellent visible light photocatalytic performance towards degrading RhB regardless of the preparation methods, in which h+ and ?O2? play the major roles examined by the trapping experiment. Above 80% RhB dyes can be degraded within 2 h after 3 cycles under visible light irradiation, suggesting the good reusability of the photocatalysts. This work demonstrates that the CFO/BiOI is characteristic with high visible light photocatalysis performance and magnetic response, hence is promising for photocatalysis.
关键词： photocatalysis,Electrospinning,BiOI nanoplates,CoFe2O4 nanofibers
更新于2025-09-09 09:28:46
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Angle dependence of synthesized BiOI prepared by dip coating and its effect on the photovoltaic performance
摘要： A study about the angle effect on the synthesis of BiOI films via modified successive ionic layer adsorption and reaction (SILAR) and its application as p-type semiconductor in solar cell construction have been carried out. By involving the angle inclination on the BiOI synthesis process in this work, it showed the impact on the BiOI film thickness. We found the thicker films contained larger flaky morphology which was displayed by the FESEM image. Also, it exhibited an increase of the Bi-I internal stretching mode (Eg) in the Raman spectra, BiOI peak absorbance in the visible region, and its crystal intensity in the XRD pattern along with the decreasing angle from 90° to 50° while SILAR process was running. Although our BiOI films performed better Jsc compared to previous studies, their photovoltaic parameters decreased slightly upon the reducing angle, which induced larger BiOI growth in the larger flaky cluster.
关键词： angle dependence,dip coating,photovoltaic performance,BiOI,SILAR
更新于2025-09-04 15:30:14
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Selective Ferroelectric BiOI/Bi4Ti3O12 Heterostructures For Visible-light-driven Photocatalysis
摘要： Ferroelectric-photocatalyst/photocatalyst heterojunctions have very attractive photocatalytic activities. Beside enhanced charge carrier separation due to their internal electric fields, charge transfer could be even further enhanced by designing the heterojunction interface. In this work, the polarization-adsorption interaction that exists in ferroelectric materials was employed for successful deposition of BiOI on specific surfaces of Bi4Ti3O12 plates in the dark at room temperature, where the positively polarized region was found. The crystal structure, morphology, and composition of samples were confirmed by X-ray diffraction, field emission scanning electron microscopy, and X-ray photoelectron spectroscopy, respectively. Higher photocatalytic activity was achieved by the use of heterojunctions, with the reason behind the enhancement of activity confirmed to be the modified band structure, which contributed to the transfer of photoelectrons from Bi4Ti3O12 to BiOI, the increased visible light absorption, the increased active site area of positively polarized Bi4Ti3O12, and the elimination of the screening layer, which contributes impedance in charge transfer.
关键词： Visible-light-driven,Photocatalysis,Heterostructures,BiOI/Bi4Ti3O12,Ferroelectric
更新于2025-09-04 15:30:14
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Facile fabrication of sandwich-like BiOI/AgI/g-C3N4 composites for efficient photocatalytic degradation of methyl orange and reduction of Cr(VI)
摘要： Construction of heterojunction photocatalyst with excellent charge separation has attracted significant attention for solving the global energy crisis and environmental problems. Herein, a series of sandwich-structured BiOI/AgI/g-C3N4 composites were fabricated by a novel and facile method. The AgI was employed as a charge transmission bridge between BiOI and g-C3N4, which could result in more efficient charge transfer and better separation of charge carriers. The results indicated that the BiOI/AgI/g-C3N4 composites exhibited higher photocatalytic activity for the degradation of methyl orange (MO) and reduction of Cr(VI) than that of pure g-C3N4, BiOI, and BiOI/g-C3N4. The amount of AgI had a remarkable influence on the photocatalytic activity of the BiOI/AgI/g-C3N4 composites. Moreover, the BiOI/AgI/g-C3N4 composites exhibited high stability. Finally, a possible reaction mechanism on degradation of MO and reduction of Cr(VI) solutions over the composites was proposed. This work could facilitate a better understanding on the charge transfer process in the composite systems as well as provide a new approach to the rational design of novel advanced materials for practical photocatalytic application.
关键词： Reaction mechanism,Photocatalytic activity,Nanocomposite,BiOI/AgI/g-C3N4
更新于2025-09-04 15:30:14