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1.
Samarium and nitrogen co‐doped Bi2WO6 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 Bi2WO6 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 Bi2WO6 possessed strong visible‐light absorption. Remarkably, the samarium and nitrogen co‐doped Bi2WO6 exhibited higher photocatalytic activity than single‐doped and pure Bi2WO6 under visible‐light irradiation. Radical trapping experiments indicated that holes (h+) and superoxide radicals ( . O2?) 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 Sm3+/Sm2+ redox pair centers and the N‐doped level. The mechanism of the excellent photocatalytic activity of Sm‐N‐Bi2WO6 is also discussed.  相似文献   

2.
Introducing plasmonic metals into semiconductor materials has been proven to be an attractive strategy for enhancing photocatalytic activity in the visible region. In this work, a novel and efficient Ag/Ag2WO4/g‐C3N4 (AACN) ternary plasmonic photocatalyst was successfully synthesized using a facile one‐step in situ hydrothermal method. The composition, structure, morphology and optical absorption properties of AACN were investigated using X‐ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and UV–visible diffuse reflectance spectroscopy, respectively. Photocatalytic performance of AACN was evaluated via rhodamine B and tetracycline degradation. The results indicated that AACN had excellent photocatalytic performance for rhodamine B degradation with a rate constant of 0.0125 min?1, which was higher than those of Ag2WO4 and Ag/Ag2WO4. Characterization and photocatalytic tests showed that the strong coupling effect between the Ag/Ag2WO4 nanoparticles and the exfoliated ultrathin g‐C3N4 nanosheets was superior for visible‐light responsivity and reduced the recombination rate of photogenerated electrons and holes. A proposed mechanism is also discussed according to the band energy structure and the experimental results.  相似文献   

3.
Visible‐light‐driven plasmonic photocatalyst Ag‐TiO2 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, N2 adsorption‐desorption isotherms, X‐ray photoelectron spectroscopy, UV/Vis and Raman spectroscopy. Production of ?OH radicals on the surface of visible‐light illuminated TiO2 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 TiO2 hollow spheres was red shifted, and a strong surface enhanced Raman scattering effect for the Ag‐TiO2 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 TiO2 and commercial Degussa P25 (P25) powders. Especially, the as‐prepared Ag‐TiO2 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   

4.
Near‐monodisperse Bi‐doped anatase TiO2 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, Bi3+ and Bi4+ ions coexist. All the Bi‐doped TiO2 samples show much better photocatalytic activity than pure TiO2 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   

5.
V5+‐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 V5+‐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% V5+‐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   

6.
The reduced graphene oxide‐Bi2WO6 (rGO‐BWO) photocatalysts with the different RF/O values (molar ratio of the F molar mass and the O's molar mass of Bi2WO6) 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 RF/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 RF/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   

7.
One‐dimensional (1D) CeO2/Bi2WO6 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 CeO2/Bi2WO6 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   

8.
Novel Bi2WO6‐coupled Fe3O4 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 Bi2WO6 and Fe3O4, and introduction of appropriated Fe3O4 can improve nanospheres morphology and visible‐light response. Among them, BFe2 (0.16% Fe3O4) 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 Fe3O4 can promote photogenerated charge carriers transfer and inhibit recombination of electron–hole pairs, so that Bi2WO6/Fe3O4 exhibited enhanced photocatalytic activity on degradation of TCH and RhB. Hence, this work provides a principle method to synthesize Bi2WO6/Fe3O4 with excellent photocatalytic performance for actual application, in addition, it showed that introduction of Fe3O4 not only can provide magnetism, but also can enhance photocatalytic activity of Bi2WO6/Fe3O4 magnetic photocatalysts.  相似文献   

9.
The mesoporous titanium dioxide (MTiO2) photocatalysts co‐doped with Fe and H3PW12O40 were synthesized by template method using tetrabutyl titanate (Ti(OC4H9)4), Fe(NO3)k39H2Oand H3PW12O40 as precursors and Pluronic P123 as template. The as‐prepared photocatalyst was characterized by N2 adsorption‐desorption measurements, X‐ray diffraction (XRD), scanning electron microscopy (SEM) and UV‐vis adsorption spectroscopy, and the photocatalytic activities of the prepared samples under UV and visible light were estimated by measuring the degradation rate of methyl blue (MB) (50 mg/L) in an aqueous solution. The characterizations indicated that the photocatalysts possessed a homogeneous pore diameter of ca. 10 nm with high surface area of ca. 150 m2/g. The results of MB photodecomposition showed that co‐doped mesoporous TiO2 exhibited higher photocatalytic activities than un‐doped, single‐doped mesoporous TiO2 under UV and visible light irradiation. It was shown that the co‐doped MTiO2 could be activated by visible light and could thus be used as an effective catalyst in photo‐oxidation reactions. The synergistic effect of Fe and H3PW12O40 co‐doping played an important role in improving the photocatalytic activity.  相似文献   

10.
An efficient method of photocatalytic degradation of methylparaben in water using Ag nanoparticles (NPs) loaded AgBr‐mesoporous‐WO3 composite photocatalyst (Ag/AgBr@m‐WO3), under visible light is presented. In this process, quantification of methylparaben in water was carried out by high‐performance liquid chromatography (HPLC) and the HPLC results showed a significant reduction of methylparaben in water due to the enhanced of photocatalytic degradation efficiency of Ag/AgBr@m‐WO3. For the material synthesis, highly ordered mesoporous‐WO3 (m‐WO3) was initially synthesized by sol–gel method and AgBr nanoparticles (NPs) were subsequently introduced in the pores of m‐WO3, and finally, the Ag nanoparticles were introduced by light irradiation. The enhanced photocatalytic degradation of methylparaben in water is attributed to the formation of surface plasmonic resonance (SPR) due to the introduction of Ag NPs on the surface of the catalyst. Also, the formation of heterojunction between AgBr and mesoporous‐WO3 in Ag/AgBr@m‐WO3 significantly inhibited the recombination of light‐induced electron‐hole pairs in the semiconductor composite. The morphological and optical characterizations of the synthesized photocatalysts (Ag/AgBr@m‐WO3) were carried out using SEM, TEM, XDR, N2 adsorption–desorption, UV‐VIS diffuse reflectance spectroscopy (DRS). Also, the photocatalytic studies using radical scavengers were carried out and the results indicated that O 2 · - is the main reactive species.  相似文献   

11.
Ag3PO4 spherical particles were synthesized by a facile precipitation method using silver nitrate and Na2HPO4 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 Ag3PO4 is proposed. Ag3PO4 spherical particles recycled for four times showed the highest photocatalytic activity because, according to our mechanism, Ag nanoparticles deposited on Ag3PO4 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 Ag3PO4. The results presented herein shed new light on the photostability of Ag3PO4 spherical particles and are potentially applicable to other photocatalytically active composites.  相似文献   

12.
Orthorhombic MoO3 and W-doped MoO3 nanobelts were successfully synthesized by a hydrothermal method. The effect of W dopant on the photocatalytic performance of W-doped MoO3 nanobelts was studied. The phase, morphology, and oxidation state of the products were characterized by X-ray diffraction analysis, Fourier-transform infrared and Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. In this research, MoO3 and W-doped MoO3 exhibited the same phase and morphology of orthorhombic nanobelts with growth along the [001] direction, including detection of Mo6+, O2?, and W6+ in the 3 mol% W-doped MoO3 sample. The photocatalytic performance of the as-synthesized MoO3 and W-doped MoO3 nanobelts was monitored through photodegradation of methylene blue (MB) under visible radiation. W-doped MoO3 nanobelts showed better photocatalytic performance than pure MoO3. The 3 mol% W-doped MoO3 photocatalyst exhibited very good visible-light-driven activity for photodegradation of MB, as high as 99 % within 60 min.  相似文献   

13.
《化学:亚洲杂志》2017,12(1):36-40
N‐doped mesoporous carbon‐capped MoO2 nanobelts (designated as MoO2@NC) were synthesized and applied to lithium‐ion storage. Owing to the stable core–shell structural framework and conductive mesoporous carbon matrix, the as‐prepared MoO2@NC shows a high specific capacity of around 700 mA h g−1 at a current of 0.5 A g−1, excellent cycling stability up to 100 cycles, and superior rate performance. The N‐doped mesoporous carbon can greatly improve the conductivity and provide uninhibited conducting pathways for fast charge transfer and transport. Moreover, the core–shell structure improved the structural integrity, leading to a high stability during the cycling process. All of these merits make the MoO2@NC to be a suitable and promising material for lithium ion battery.  相似文献   

14.
Limited by the relatively sluggish charge‐carrier separation in semiconductors, the photocatalytic performance is still far below what is expected. Herein, a model of ZnIn2S4 (ZIS) nanosheets with oxygen doping is put forward to obtain in‐depth understanding of the role that doping atoms play in photocatalysis. It shows enhanced photocatalytic activity compared with pristine ZIS. The electron dynamics analyzed by ultrafast transient absorption spectroscopy reveals that the average recovery lifetime of photoexcited electrons is increased by 1.53 times upon oxygen incorporation into the ZIS crystals, indicating enhanced separation of photoexcited carriers in oxygen‐doped ZIS nanosheets. As expected, the oxygen‐doped ZIS nanosheets show a remarkably improved photocatalytic activity with a hydrogen evolution rate of up to 2120 μmol h?1 g?1 under visible‐light irradiation, which is 4.5 times higher than that of the pristine ZIS nanosheets.  相似文献   

15.
Ag nanoparticle (NP)‐decorated MIL‐125(Ti) microspheres (Ag@MIL‐125(Ti)) were firstly fabricated via a facile hydrothermal and following photo‐reduction method. The photocatalysts were characterized using X‐ray diffraction, scanning and transmission electron microscopies, X‐ray photoelectron spectroscopy and UV–visible diffuse reflectance spectroscopy. The characterization results indicated that Ag NPs were dispersed on the surface of MIL‐125(Ti) microspheres, and the Ag NPs had a uniform diameter of about 40 nm. The composites exhibited excellent visible‐light absorption, due to the modification with the Ag NPs. The photocatalytic activity for the visible‐light‐promoted degradation of Rhodamine B was improved through the optimization of the amount of Ag loaded as a co‐catalyst, this amount being determined as 3 wt%. Additionally, studies performed using radical scavengers indicated that O2? and e? served as the main reactive species. The catalyst can be reused at least five times without significant loss of its catalytic activity. Furthermore, a photocatalytic mechanism for degradation of organics over Ag@MIL‐125(Ti) is also proposed. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

16.
《中国化学会会志》2017,64(10):1172-1180
The Ag/Ag3PO4 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/Ag3PO4 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/Ag3PO4 composites are also discussed. The decomposition test of rhodamine B (RhB) indicated that the Ag/Ag3PO4 composites enhanced the photocatalytic performance compared with pure Ag3PO4, which was attributed to the surface plasmon resonance (SPR) of Ag nanoparticles and the stability of the photocatalysts. Moreover, uniform cubes of Ag/Ag3PO4 showed the highest photocatalytic activity and could completely degrade RhB in 7 min, which could be primarily ascribed to the cubic structure of Ag/Ag3PO4 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   

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 Ti3+–Ti4+ 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.
KSbWO6 was prepared by sol‐gel method. N‐doped KSbWO6 (KSbWO6–xNx) was obtained by heating KSbWO6 and urea at 400 °C. Both the compounds are characterized by powder X‐ray diffraction (XRD), TEM, SEM‐EDS, X‐ray photo electronic spectroscopy (XPS), and UV/Vis diffuse reflectance spectroscopy (UV‐DRS). A shift in the peak positions of powder XRD and XPS spectra was observed. The band gap energy (Eg) of KSbWO6 and N‐doped KSbWO6 was obtained from their diffused reflectance spectra.Eg was reduced from 3.17 eV to 2.56 eV upon nitrogen doping in KSbWO6. The reduction of the Eg is attributed to the lifting of valence band of N‐doped KSbWO6, due to the mixing of O 2p states with N 2p states. The photocatalytic activity of both the samples was studied by degradation of methylene blue (MB). The nitrogen doped KSbWO6 shows higher photocatalytic activity compared to that of KSbWO6.  相似文献   

19.
In this paper, a novel TiO2 nanosheets assembled double‐wall hollow sphere (DHS)has been prepared successfully via hydrothermal treatment of SiO2@TiO2 with the assistant of CTAB.The prepared samples are characterized with transmission electron microscopy (TEM), scanning electron microscopy (SEM), electron spin resonance (ESR), X‐ray diffraction (XRD) and X‐ray photoelectron spectra (XPS), etc.Results show that redeposited silica species play a key role in the formation of the double‐wall structure. The as‐synthesized DHS nanostructure exhibits a large surface area (417.6 m2 g‐1) and excellent mechanical strength. Furthermore, after decoration of Ag and calcination treatment, the double‐shelled TiO2/Ag heterostructures show an enhanced photocatalytic performance in the degradation of RhB under UV or visible light irradiations for the following reasons: the surface plasmon resonance effect of Ag, strong interaction between Ag and TiO2 nanosheets, large surface area, excellent adsorption capacityand unique double‐wall structure. On the basis of the experimental results, a possible mechanism for pollutantdegradation under visual light irradiation has been proposed.  相似文献   

20.
Graphene oxide/Mg‐doped ZnO/tungsten oxide quantum dots composites (WQGOMZ) were prepared through co‐precipitation method, and were studied by X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray photoelectron spectroscopy (XPS), Fluorescence spectra (FL), and UV–vis diffuse reflection spectra. Furthermore, the photocatalytic activity of resultant WQGOMZ was evaluated under nature sunlight. Experimental results showed that WO3QDs can remarkably heighten the photocatalytic activity of GOMZ composite, in which is nearly 6.58 times higher than that of GOMZ composite. Simultaneously, WQGOMZ composites possess optical memory ability and maintain high photocatalytic stability for more than 40 days. The enhanced photocatalytic activity and optical memory ability are attributed to the effective synergistic effect between ZnO and WO3QDs.  相似文献   

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