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1.
The surface modification of Ag/Ag 2CO 3 with Fe(III) ions has been achieved through simply photoreduction‐impregnation method. The obtained products were characterized by means of X‐ray diffraction (XRD), scanning electron microscopy (SEM), X‐ray photoelectron spectroscopy (XPS), and UV‐vis absorption spectroscopy. Under visible‐light irradiation (γ>420 nm), the Fe(III)/Ag/Ag 2CO 3 sample displays a higher photocatalytic activity and stability than pure Ag 2CO 3 and Ag/Ag 2CO 3 samples for the degradation of methyl orange (MO). The improved photocatalytic activity and stability of this ternary system could be ascribed to the synergetic effect between Ag nanoparticles and Fe(III) nanocluster. The metallic Ag nanoparticles cause an obviously enhanced visible‐light absorption to produce more photogenerated charges, while the Fe(III) works as an active site for the following oxygen reduction to reduce the recombination rate of photogenerated electrons and holes. 相似文献
2.
Visible‐light‐driven plasmonic photocatalyst Ag‐TiO 2 nanocomposite hollow spheres are prepared by a template‐free chemically‐induced self‐transformation strategy under microwave‐hydrothermal conditions, followed by a photochemical reduction process under xenon lamp irradiation. The prepared samples are characterized by using scanning electron microscopy, transmission electron microscopy, X‐ray diffraction, N 2 adsorption‐desorption isotherms, X‐ray photoelectron spectroscopy, UV/Vis and Raman spectroscopy. Production of ?OH radicals on the surface of visible‐light illuminated TiO 2 was detected by using a photoluminescence method with terephthalic acid as the probe molecule. The photocatalytic activity of as‐prepared samples was evaluated by photocatalytic decolorization of Rhodamine B (RhB) aqueous solution at ambient temperature under visible‐light irradiation. The results show that the surface plasmon absorption band of the silver nanoparticles supported on the TiO 2 hollow spheres was red shifted, and a strong surface enhanced Raman scattering effect for the Ag‐TiO 2 nanocomposite sample was observed. The prepared nanocomposite hollow spheres exhibits a highly visible‐light photocatalytic activity for photocatalytic degradation of RhB in water, and their photocatalytic activity is higher than that of pure TiO 2 and commercial Degussa P25 (P25) powders. Especially, the as‐prepared Ag‐TiO 2 nanocomposite hollow spheres at the nominal atomic ratio of silver to titanium ( R ) of 2 showed the highest photocatalytic activity, which exceeds that of P25 by a factor of more than 2. 相似文献
3.
Novel Bi 2WO 6‐coupled Fe 3O 4 magnetic photocatalysts with excellent and stable photocatalytic activity for degrading tetracycline hydrochloride and RhB were successfully synthesized via a facile solvothermal route. Through the characterization of the as‐prepared magnetic photocatalysts by X‐ray diffractometry, scanning electron microscopy, transmission electron microscopy, X‐ray photoelectron spectroscopy, UV–Vis diffuse reflectance spectra, it was found that the as‐prepared magnetic photocatalysts were synthesized by the coupling of Bi 2WO 6 and Fe 3O 4, and introduction of appropriated Fe 3O 4 can improve nanospheres morphology and visible‐light response. Among them, BFe2 (0.16% Fe 3O 4) exhibited the best photocatalytic activity for degradation of tetracycline hydrochloride (TCH), reaching 81.53% after 90 min. Meanwhile, the as‐prepared magnetic photocatalysts showed great separation and recycle property. Moreover, the results of electrochemical impedance spectroscopy demonstrated that the well conductivity of Fe 3O 4 can promote photogenerated charge carriers transfer and inhibit recombination of electron–hole pairs, so that Bi 2WO 6/Fe 3O 4 exhibited enhanced photocatalytic activity on degradation of TCH and RhB. Hence, this work provides a principle method to synthesize Bi 2WO 6/Fe 3O 4 with excellent photocatalytic performance for actual application, in addition, it showed that introduction of Fe 3O 4 not only can provide magnetism, but also can enhance photocatalytic activity of Bi 2WO 6/Fe 3O 4 magnetic photocatalysts. 相似文献
4.
V 5+‐doped Ag/AgCl photocatalysts were prepared via the ion exchange method. The catalysts were characterized using X‐ray diffractometry, transmission electron microscopy, and energy‐dispersive X‐ray, X‐ray photoelectron, Fourier transform infrared and ultraviolet–visible spectroscopies. The V 5+‐doped Ag/AgCl photocatalysts show much higher photocatalytic activities than Ag/AgCl under visible light irradiation for methyl orange (MO) decomposition. Especially, the 2.0 wt% V 5+‐doped Ag/AgCl photocatalyst shows the highest photocatalytic activity and also high stability after five cycles. The MO degradation rate during each cycle is almost maintained at 97%. Electron spin resonance spectroscopy and radical trapping experiments reveal that holes play an important role in the photocatalytic process. 相似文献
5.
In this study, the characterization and photocatalytic activity of Bi 2WO 6/Bi 2O 3 under visible‐light irradiation was investigated in detail. The results suggested that Bi 2WO 6/Bi 2O 3 can be synthesized by a facile one‐pot hydrothermal route using a super big 200 mL Teflon‐lined autoclave with optimal sodium oleate/Bi molar ratio of 1.25. Through the characterization of Bi 2WO 6/Bi 2O 3 by X‐ray diffraction, scanning electron microscopy, X‐ray photoelectron spectroscopy, Fourier transform infrared, UV‐vis diffuse reflectance spectra and Photoluminescence spectra, it was found that the as‐prepared composite possessed smaller crystallite size and higher visible‐light responsive than the pure Bi 2WO 6. Moreover, it was expected that the as‐prepared composites exhibited enhanced photocatalytic activity for the degradation of Rhodamine B under visible‐light irradiation, which could be ascribed to their improved light absorption property and the reduced recombination of the photogenerated electrons and holes during the photocatalytic reaction. In general, this study could provide a principle method to synthesize Bi 2WO 6/Bi 2O 3 with enhanced photocatalytic activity by one‐step hydrothermal synthesis route for environmental purification. 相似文献
6.
MgFe 2O 4 implanted with ZnO and silver nanoparticles has been successfully synthesized. The formation mechanism of the core~shell structured Ag/ZnO /MgFe 2O 4 nanoparticles was investigated. The efficacy of degradation of an organic dye was compared under the visible light irradiation with the individual components (MgFe 2O 4 , ZnO , and Ag). The structure of Ag/ZnO /MgFe 2O 4 nanoparticles was established from detailed structural analyses using a vibrating‐sample magnetometer (VSM), X‐ray diffraction (XRD ), selected area electron diffraction (SAED ), scanning electron microscopy (SEM ), energy‐dispersive X‐ray spectroscopy (EDS ), and transmission electron microscopy (TEM ). Ag/ZnO /MgFe 2O 4 nanoparticles showed a saturation magnetization ( M s) of 44 emu/g. It is seen from the results that ZnO is coated on the surface of MgFe 2O 4 nanoparticles, and Ag nanoparticles are attached to the edge of the ZnO /MgFe 2O 4 nanoparticles. In addition, the nanoparticles were found to be spherical with appropriate structures. The electron transfer mechanism greatly enhances the rhodamine B (RhB ) degradation rate, which is illustrated and discussed in detail. The obtained Ag/ZnO /MgFe 2O 4 nanoparticles were photostable and magnetically recyclable with potential application in the degradation of organic pollutants. 相似文献
7.
In this paper, Bi 2O 3 and rare earth (La, Ce)‐doped Bi 2O 3 visible‐light‐driven photocatalysts were prepared in a Triton X‐100/ n‐hexanol/cyclohexane/water reverse microemulsion. The resulting materials were characterized by X‐ray powder diffraction (XRD), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) surface area, photoluminescence spectra (PLS) and UV–Vis diffuse reflectance spectroscopy. The XRD patterns of the as‐prepared catalysts calcined at 500°C exhibited only the characteristic peaks of monoclinic α‐Bi 2O 3. PLS analysis implied that the separation efficiency for electron‐hole has been enhanced when Bi 2O 3 was doped with rare earth. UV–Vis diffuse reflectance spectroscopy measurements presented an extension of light absorption into the visible region. The photocatalytic activity of the samples was evaluated by degradation of methyl orange (MO) and 2,4‐dichlorophenol (2,4‐DCP). The results displayed that the photocatalytic activity of rare earth‐doped Bi 2O 3 was higher than that of dopant‐free Bi 2O 3. The optimal dopant amount of La or Ce was 1.0 mol%. And the mechanisms of influence on the photocatalytic activity of the catalysts were discussed. 相似文献
8.
The Ag/Ag 3PO 4 composites with various shapes (spheres, polyhedral, and microcubes) were synthesized by a facile precipitation method and a subsequent light‐reduction route at room temperature. The as‐prepared Ag/Ag 3PO 4 composites were characterized in detail by X‐ray diffraction, Fourier transform infrared spectra, X‐ray photoelectron spectroscopy, scanning electron microscopy, UV–vis diffuse reflection, and photoluminescence spectroscopy. The growth processes of different morphologies Ag/Ag 3PO 4 composites are also discussed. The decomposition test of rhodamine B (RhB) indicated that the Ag/Ag 3PO 4 composites enhanced the photocatalytic performance compared with pure Ag 3PO 4, which was attributed to the surface plasmon resonance (SPR) of Ag nanoparticles and the stability of the photocatalysts. Moreover, uniform cubes of Ag/Ag 3PO 4 showed the highest photocatalytic activity and could completely degrade RhB in 7 min, which could be primarily ascribed to the cubic structure of Ag/Ag 3PO 4 with strong visible‐light absorption and efficient separation of the photo‐generated electrons and holes. Furthermore, the possible photocatalytic mechanism is also discussed. 相似文献
9.
Visible-light-driven heterostructure Ag/Bi2WO6 nanocomposites were prepared by transforming Ag+ ions into metallic Ag0 nanoparticles loaded on top of Bi2WO6 nanoplates under visible light irradiation for 1 h. XRD, XPS, SEM and TEM analyses indicated that spherical metallic Ag nanoparticles were uniformly dispersed on top of orthorhombic Bi2WO6 thin nanoplates. Rhodamine B (RhB) was used as a dye model for investigation of photocatalytic performance of Bi2WO6 nanoplates with different weight contents of Ag nanoparticles illuminated by visible radiation. In this research, 10% Ag/Bi2WO6 nanocomposites have the highest photocatalytic activity in the degradation of RhB at 94.21% within 210 min because of the rapid diffusion of electronic charge through the Schottky barrier between metallic Ag nanoparticles and Bi2WO6 thin nanoplates, good electrical conductivity of metallic Ag nanoparticles, inhibited recombination of charge carriers and enhanced photocatalytic activity of Ag/Bi2WO6 nanocomposites. Main active species of the photocatalysis and stability of the photocatalyst were also evaluated. 相似文献
10.
Ag 3PO 4 spherical particles were synthesized by a facile precipitation method using silver nitrate and Na 2HPO 4 as precursors. The as‐prepared samples had a high photocatalytic activity toward Rhodamine B (RhB) degradation under visible‐light illumination. With increasing recycling times the photocatalytic activity first increased and then decreased. Based on systematic characterization of particles by X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), UV/Vis absorption spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM), a possible mechanism responsible for the improvement and subsequent decline of the photocatalytic performance of Ag 3PO 4 is proposed. Ag 3PO 4 spherical particles recycled for four times showed the highest photocatalytic activity because, according to our mechanism, Ag nanoparticles deposited on Ag 3PO 4 acted as electron trapping centers to prevent photogenerated electron‐hole pairs from recombination. A further increase in the recycle times decreases the photocatalytic activity owing to the shielding effect by Ag layers on the surface of Ag 3PO 4. The results presented herein shed new light on the photostability of Ag 3PO 4 spherical particles and are potentially applicable to other photocatalytically active composites. 相似文献
11.
One‐dimensional (1D) CeO 2/Bi 2WO 6 heterostructured nanofibers with a diameter of about 300 nm were successfully synthesized by using a straightforward strategy combining an electrospinning technique with a sintering process. The acquired products were characterized by thermogravimetric and differential scanning calorimetric (TG‐DSC), Fourier transform infrared (FT‐IR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) surface area measurements, and UV/Vis spectroscopy. The obtained CeO 2/Bi 2WO 6 heterostructured nanofibers exhibited an excellent photocatalytic property for the degradation of Rhodamine B (RhB) dye driven by visible light due to the promoted separation of photoelectrons and holes and the large contact area between the photocatalyst and organic pollutant. 相似文献
12.
In this paper, an Ag‐doped WO 3 (and MoO 3) composite has been prepared by following a simple micelle‐directed method and high‐temperature sintering route. The as‐prepared samples were characterized by X‐ray diffraction, inductively coupled plasma, transmission electron microscopy, X‐ray photoelectron spectroscopy, UV/Vis diffuse reflectance spectroscopy, Brunauer–Emmett–Teller, photoluminescence spectroscopy, and electrochemical impedance spectroscopy techniques. The photocatalytic experiments reveal that their oxygen‐production rates are up to 95.43 μmol (75.45 μmol) for Ag‐doped WO 3 (MoO 3), which is 9.5 (7.3) times higher than that of pure WO 3: 9.012 μmol (MoO 3: 9.00 μmol) under visible‐light illumination ( λ ≥420 nm), respectively. The improvement of their photocatalytic activity is attributed to the enhancement of their visible‐light absorption and the separation efficiency of photogenerated carriers by Ag doping. Moreover, Ag‐doped WO 3 (MoO 3) also shows excellent adsorption of rhodamine B (RhB) and methylene blue (MB) in aqueous solution, with maximum adsorption capacities towards RhB and MB of 822 and 820 mg g −1 for Ag‐doped WO 3, and 642 and 805 mg g −1 for Ag‐doped MoO 3, respectively. 相似文献
13.
Samarium and nitrogen co‐doped Bi 2WO 6 nanosheets were successfully synthesized by using a hydrothermal method. The crystal structures, morphology, elemental compositions, and optical properties of the prepared samples were investigated. The incorporation of samarium and nitrogen ions into Bi 2WO 6 was proved by X‐ray diffraction, energy dispersive X‐ray spectroscopy, and X‐ray photoelectron spectroscopy. UV/Vis diffuse reflectance spectroscopy indicated that the samarium and nitrogen co‐doped Bi 2WO 6 possessed strong visible‐light absorption. Remarkably, the samarium and nitrogen co‐doped Bi 2WO 6 exhibited higher photocatalytic activity than single‐doped and pure Bi 2WO 6 under visible‐light irradiation. Radical trapping experiments indicated that holes (h +) and superoxide radicals ( . O 2?) were the main active species. The results of photoluminescence spectroscopy and photocurrent measurements demonstrated that the recombination rate of the photogenerated electrons and holes pairs was greatly depressed. The enhanced activity was attributed to the synergistic effect of the in‐built Sm 3+/Sm 2+ redox pair centers and the N‐doped level. The mechanism of the excellent photocatalytic activity of Sm‐N‐Bi 2WO 6 is also discussed. 相似文献
14.
The reduced graphene oxide‐Bi 2WO 6 (rGO‐BWO) photocatalysts with the different R F/O values (molar ratio of the F molar mass and the O's molar mass of Bi 2WO 6) had been successfully synthesized via one‐step hydrothermal method. The F‐doped rGO‐BWO samples were characterized by X‐ray diffraction patterns (XRD), field‐emission scanning electron microscopy (FE‐ESEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller surface area (BET), X‐ray photoelectron spectroscopy (XPS) and UV–vis diffuse reflectance spectra (DRS). The results indicate that F ? ions had been successfully doped into rGO‐BWO samples. With the increasing of the R F/O values from 0 to 2%, the evident change of the morphology and the absorption edges of F‐doped rGO‐BWO samples and the photocatalytic activities had been enhanced. Moreover, the photocatalytic activity of F‐doped rGO‐BWO with R F/O = 0.05 were better than rGO‐BWO and the other F‐doped rGO‐BWO under 500 W Xe lamp light irradiation. The enhanced photocatalytic activity can be attributed to the morphology of the intact microsphere that signify the bigger specific surface area for providing more possible reaction sites for the adsorption–desorption equilibrium of photocatalytic reaction, the introduction of F ? ions that may cause the enhancement of surface acidity and creation of oxygen vacancies under visible light irradiation, the narrower band gap which means needing less energy for the electron hole pair transition. 相似文献
15.
A novel and facile method was developed to prepare a visible‐light driven TiO 2/Ag‐AgCl@polypyrrole (PPy) photocatalyst with Ag‐AgCl nanoparticles supported on TiO 2 nanofibers and covered by a thin PPy shell. During the synthesis, the PPy shell and Ag‐AgCl nanoparticles were prepared simultaneously onto TiO 2 nanofibers, which simplified the preparation procedure. In addition, because Ag‐AgCl aggregates were fabricated via partly etching the Ag nanoparticles, their size was well controlled at the nanoscale, which was beneficial for improvement of the contact surface area. Compared with reference photocatalysts, the TiO 2/Ag‐AgCl@PPy composite exhibited an enhanced photodegradation activity towards rhodamine B under visible‐light irradiation. The superior photocatalytic property originated from synergistic effects between TiO 2 nanofibers, Ag‐AgCl nanoparticles and the PPy shell. Furthermore, the TiO 2/Ag‐AgCl@PPy composite could be easily separated and recycled without obvious reduction in activity. 相似文献
16.
Visible light‐driven Al‐doped TiO 2 with different aluminum contents (2, 5 and 10 mol%) were synthesized via a facile sol–gel method. Fourier transform infrared (FTIR), UV‐visible diffuse reflectance, energy dispersive X ‐ray (EDX) spectroscopy as well as X‐ray diffraction (XRD), X‐ray fluorescence (XRF) and scanning electron microscopy (SEM) methods were used for the characterization of the obtained nanoparticles. The photocatalytic performance of the samples was evaluated by the degradation of rhodamine B (RhB) under visible light irradiation. The yield of the degradation RhB was estimated to be 71%, 89%, 65% and 56%, for the bare TiO 2, 2%, 5% and 10% Al‐doped TiO 2, respectively. It was found that 2 mol% of Al‐doped TiO 2 shows the best photocatalytic performance. In low concentration of dopant, separation of photogenerated electron–hole pairs promoted, and subsequently, the degradation efficiency increased. It was proposed that the degradation of RhB by 2 mol% Al‐doped TiO 2 photocatalyst follows both N‐deethylation and chromophore cleavage mechanisms, while the N‐deethylation still predominated over cleavage of dye chromophore structure. The key role of hydroxyl radicals in RhB degradation was verified by the effects of scavengers. In addition, the photocatalyst can be reused for three runs without any significant loss of its catalytic activity. 相似文献
17.
In recent years, tremendous research efforts have been made towards developing metal–organic framework (MOF)‐based composites for photocatalytic applications. In this work, bipyramid‐like MIL‐125(Ti) frustum enwrapped with reduced graphene oxide (rGO) and dispersed silver nanoparticles (Ag NPs) was fabricated using an efficient one‐pot self‐assembly and photoreduction strategy. The as‐obtained materials were characterized using field emission scanning electron microscopy, transmission electron microscopy, X‐ray diffraction, nitrogen adsorption–desorption isotherms, and X‐ray photoelectron, ultraviolet–visible diffuse reflectance and photoluminescence spectroscopies. It is found that the as‐prepared Ag/rGO/MIL‐125(Ti) ternary hybrids have large surface area, microporous structure, enhanced visible light absorption and prolonged lifetime of charge carriers. Compared with pure MIL‐125(Ti) and its binary counterparts, the ternary composite exhibits more efficient photocatalytic performance for Rhodamine B (RhB) degradation from water under visible light irradiation. The photodegradation rate of RhB on Ag/rGO/MIL‐125(Ti) is 0.0644 min ?1, which is 1.62 times higher than that of the pure MIL‐125(Ti). The improved photocatalytic performance is ascribed to the indirect dye photosensitization, the Ag NP localized surface plasmon resonance, the Ti 3+–Ti 4+ intervalence electron transfer and the synergistic effect among MIL‐125(Ti), Ag NPs and rGO. Ag NPs serve as an efficient ‘electron reservoir’ and rGO as an electron transporter and collector. Therefore, this work provides a new pathway into the design of MOF‐based composites for application in environmental and energy fields. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
18.
Flake BiOBr was first prepared by a solution method at room temperature. Then, the produced BiOBr was calcined at different temperatures. It was found that BiOBr is not a stable compound. It transforms to plate‐like Bi 24O 31Br 11at around 750°C and the formed Bi 24O 31Br 11 can further convert to rod‐like α‐Bi 2O 3 at around 850°C. The prepared compounds were characterized with X‐ray diffraction (XRD), N 2 physical adsorption, scanning electron microscopy (SEM), and UV‐Vis diffuse reflectance spectra (DRS), respectively. The photocatalytic activity of the produced bismuth oxybromides was evaluated by photocatalytic decomposition of acid orange II under both visible light ( λ>420 nm) and UV light ( λ=365 nm) irradiation. Results show that these compounds have different band gaps and different photocatalytic properties. The band gap energies of the as‐prepared samples were found to be 2.82, 2.79, 2.60 and 3.15 eV for BiOBr, BiOBr/Bi 24O 31Br, Bi 24O 31Br, and α‐Bi 2O 3, respectively. Under both UV light and visible light irradiation, the photocatalytic activity follows the order: BiOBr/Bi 24O 31Br mixture>BiOBr>Bi 24O 31Br> α‐Bi 2O 3. The change in photocatalytic activity could be attributed to the different light absorption ability and microstructures of the photocatalysts. 相似文献
19.
A Bi2O3/(BiO)2CO3 (BO/BOC) composite photocatalyst was in situ prepared via calcinating (BiO)2CO3. The as-prepared Bi2O3/(BiO)2CO3 composites displayed enhanced photocatalytic activity for the degradation of RhB under visible light. The structure–activity relationship between catalyst structure and properties was investigated by SEM, XRD, XPS, FTIR, BET, DRS and photoelectrochemical tests. Apart from the increased absorption of visible light, the accelerated charge separation and transfer was achieved via the intimate contact and matched band structure between Bi2O3 and (BiO)2CO3. The formation of heterogeneous structures could promote the production of reactive oxygen species (·O2?) and eventually improve the photocatalytic performance for the removal of organic contaminants. This heating treatment strategy might be extended for improving light absorbance and charge carriers separation for other UV-based photocatalysts. 相似文献
20.
Near‐monodisperse Bi‐doped anatase TiO 2 nanospheres with almost uniform diameters in the range of 117 to 87 nm were prepared simply by introducing different amounts of bismuth nitrate pentahydrate into the reaction system and subsequent calcinations. X‐ray diffraction, UV‐visible diffuse reflectance spectra, and X‐ray photoelectron spectroscopy confirm that the doped ions substitute some of the lattice titanium atoms, and furthermore, Bi 3+ and Bi 4+ ions coexist. All the Bi‐doped TiO 2 samples show much better photocatalytic activity than pure TiO 2 in the degradation of rhodamine B (RhB) under the irradiation of visible light ( λ>420 nm), and, interestingly, it was found that the degradation mechanism is different from the conventional one, which has already been reported elsewhere. The detailed mechanism is discussed in this article. 相似文献
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