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Preparation of Ag-doped Bi5O7I composites with enhanced visible-light-induced photocatalytic performance
摘要： A novel heterostructure photocatalysts, Ag-doped Bi5O7I composites (Ag/Bi5O7I), were synthesized by a simple hydrothermal method. Compared with Bi5O7I, Ag/Bi5O7I composites had a stronger light absorption in the visible and near-infrared region and the light absorption edge of Ag/Bi5O7I composites had a slight red shift. Moreover, Ag/Bi5O7I composites possessed a higher photocatalytic activity than Bi5O7I on the degradation of rhodamine B (RhB) and methyl orange (MO) under visible-light irradiation (λ ≥ 420 nm). When the content of Ag was 1%, the degradation efficiency of the Ag/Bi5O7I composites toward RhB and MO reached the maximum value, which was about 20.2 and 7.6 times higher than that of Bi5O7I, respectively. The trapping experiments shown that superoxide radicals and holes were the main active species in the photodegradation process. The excellent photocatalytic performance could be attributed to Ag/Bi5O7I heterojunction and surface plasma resonance effect of Ag, which could increase absorption of visible light and cause the efficient separation and migration of carriers.
关键词： Ag-doped Bi5O7I,Visible-light,Surface plasma resonance,Heterostructure photocatalysts
更新于2025-11-14 17:03:37
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Construction of nitrogen and phosphorus co-doped graphene quantum dots/Bi5O7I composites for accelerated charge separation and enhanced photocatalytic degradation performance
摘要： Nitrogen and phosphorus co-doped graphene quantum dot-modified Bi5O7I (NPG/Bi5O7I) nanorods were fabricated via a simple solvothermal method. The morphology, structure, and optical properties of the as-prepared samples were investigated by X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy (XPS), and diffused reflectance spectroscopy. The photocatalytic performance was estimated by degrading the broad-spectrum antibiotics tetracycline and enrofloxacin under visible light irradiation. The photodegradation activity of Bi5O7I improved after its surface was modified with NPGs, which was attributed to an increase in the photogenerated charge transport rate and a decrease in the electron-hole pair recombination efficiency. From the electron spin resonance spectra, XPS valence band data, and free radical trapping experiment results, the main active substances involved in the photocatalytic degradation process were determined to be photogenerated holes and superoxide radicals. A possible photocatalytic degradation mechanism for NPG/Bi5O7I nanorods was proposed.
关键词： Charge separation,Photocatalysis,Bi5O7I,N,P co-doped graphene quantum dots,Ionic liquid
更新于2025-09-23 15:21:01
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Plasmon Ag and CdS quantum dot co-decorated 3D hierarchical ball-flower-like Bi <sub/>5</sub> O <sub/>7</sub> I nanosheets as tandem heterojunctions for enhanced photothermal–photocatalytic performance
摘要： Plasmon Ag and CdS quantum dot co-decorated three-dimensional (3D) hierarchical ball-flower-like Bi5O7I nanosheets as tandem heterojunction photocatalysts are synthesized by oil bath, photoreduction and hydrothermal processes. The formation of a tandem heterojunction structure facilitates the migration and spatial separation of photogenerated electron–hole pairs. Plasmon Ag nanoparticles can generate hot electrons to enhance the photothermal performance due to the surface plasmon resonance (SPR) effect. The unique 3D hierarchical ball-flower-like Bi5O7I nanosheets can provide a number of surface active sites and allow incident light to be reflected multiple times within the Bi5O7I nanosheets, thus improving the light utilization. Under the protection of Bi5O7I nanosheets, CdS quantum dots which are deposited by a hydrothermal strategy can effectively avoid photocorrosion. In addition, the introduction of Ag nanoparticles and CdS quantum dots extends the photoresponse to the near infrared (NIR) region. The photocatalytic degradation rate of Bi5O7I/Ag/CdS composites with a CdS content of 5.76 wt% exhibits the best photocatalytic activity, which is several times higher than that of pristine Bi5O7I. The photocatalytic hydrogen evolution is about 10 times higher than that over Bi5O7I nanosheets. Moreover, the photothermal efficiency of Bi5O7I/Ag/CdS is also improved obviously. The results of cyclic experiments show that the composite photocatalysts have high stability. The outstanding photocatalytic and photothermal performance is attributed to the formation of tandem heterojunctions favoring the separation of charge carriers, the 3D hierarchical structure of Bi5O7I offering adequate surface active sites, and the SPR effect of Ag promoting the photothermal effect. These novel Bi5O7I/Ag/CdS tandem heterojunctions may provide a new insight into the synthesis of other photocatalysts with synergistic photocatalytic–photothermal effects.
关键词： tandem heterojunctions,photothermal–photocatalytic performance,Bi5O7I nanosheets,CdS quantum dot,Plasmon Ag
更新于2025-09-16 10:30:52
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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