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1.
In this study, the photocatalytic efficiency of anatase‐type TiO2 nanoparticles synthesized using the sol–gel low‐temperature method, were enhanced by a combined process of copper reduction and surface hydroxyl groups enhancement. UV–light‐assisted photo and NaBH4‐assisted chemical reduction methods were used for deposition of copper onto TiO2. The surface hydroxyl groups of TiO2 were enhanced with the assistance of NaOH modification. The prepared catalysts were immobilized on glass plates and used as the fixed‐bed systems for the removal of phenazopyridine as a model drug contaminant under visible light irradiation. NaOH‐modified Cu/TiO2 nanoparticles demonstrated higher photocatalytic efficiency than that of pure TiO2 due to the extending of the charge carriers lifetime and enhancement of the adsorption capacity of TiO2 toward phenazopyridine. The relationship of structure and performance of prepared nanoparticles has been established by using various techniques, such as XRD, XPS, TEM, EDX, XRF, TGA, DRS and PL. The effects of preparation variables, including copper content, reducing agents rate (NaBH4 concentration and UV light intensity) and NaOH concentration were investigated on the photocatalytic efficiency of NaOH‐modified Cu/TiO2 nanoparticles.  相似文献   

2.
The need for renewable energy focuses attention on hydrogen obtained by using sustainable and green methods. The sustainable compound glycerol can be used for hydrogen production by heterogeneous photocatalysis. A novel approach involves the promotion of the TiO2 photocatalyst with a binary combination of nitrogen and transition metal. We report the synthesis and spectroscopic characterization of the new N‐M‐TiO2 photocatalysts (M=none, Cr, Co, Ni, Cu), and the photocatalytic reforming of glycerol to hydrogen under ambient conditions and near‐UV or visible light versus benchmark P25 TiO2. In units of activity μmol m?2 h?1, N‐Ni‐TiO2 is five‐fold more active than P25, and N‐Cu‐TiO2 is 44‐fold more active. The photocatalytic activity of N‐M‐TiO2 increases from Cr to Co and Ni, whereas the photoluminescence decreases; the change in activity is due to the modulation of charge recombination.  相似文献   

3.
The aim of this study is to clarify the effect of doped metal type on CO2 reduction characteristics of TiO2 with NH3 and H2O. Cu and Pd have been selected as dopants for TiO2. In addition, the impact of molar ratio of CO2 to reductants NH3 and H2O has been investigated. A TiO2 photocatalyst was prepared by a sol-gel and dip-coating process, and then doped with Cu or Pd fine particles by using the pulse arc plasma gun method. The prepared Cu/TiO2 film and Pd/TiO2 film were characterized by SEM, EPMA, TEM, STEM, EDX, EDS and EELS. This study also has investigated the performance of CO2 reduction under the illumination condition of Xe lamp with or without ultraviolet (UV) light. As a result, it is revealed that the CO2 reduction performance with Cu/TiO2 under the illumination condition of Xe lamp with UV light is the highest when the molar ratio of CO2/NH3/H2O = 1:1:1 while that without UV light is the highest when the molar ratio of CO2/NH3/H2O = 1:0.5:0.5. It is revealed that the CO2 reduction performance of Pd/TiO2 is the highest for the molar ratio of CO2/NH3/H2O = 1:1:1 no matter the used Xe lamp was with or without UV light. The molar quantity of CO per unit weight of photocatalyst for Cu/TiO2 produced under the illumination condition of Xe lamp with UV light was 10.2 μmol/g, while that for Pd/TiO2 was 5.5 μmol/g. Meanwhile, the molar quantity of CO per unit weight of photocatalyst for Cu/TiO2 produced under the illumination condition of Xe lamp without UV light was 2.5 μmol/g, while that for Pd/TiO2 was 3.5 μmol/g. This study has concluded that Cu/TiO2 is superior to Pd/TiO2 from the viewpoint of the molar quantity of CO per unit weight of photocatalyst as well as the quantum efficiency.  相似文献   

4.
A magnetized nano‐photocatalyst based on TiO2/magnetic graphene was developed for efficient photodegradation of crystal violet (CV). Scanning electron microscopy, X‐ray diffraction, energy‐dispersive X‐ray spectroscopy and elemental mapping were used to characterize the prepared magnetic nano‐photocatalyst. The photocatalytic activity of the synthesized magnetic nano‐photocatalyst was evaluated using the decomposition of CV as a model organic pollutant under UV light irradiation. The obtained results showed that TiO2/magnetic graphene exhibited much higher photocatalytic performance than bare TiO2. Incorporation of graphene enhanced the activity of the prepared magnetic nano‐photocatalyst. TiO2/magnetic graphene can be easily separated from an aqueous solution by applying an external magnetic field. Effects of pH, magnetized nano‐photocatalyst dosage, UV light irradiation time, H2O2 amount and initial concentration of dye on the photodegradation efficiency were evaluated and optimized. Efficient photodegradation (>98%) of the selected dye under optimized conditions using the synthesized nano‐photocatalyst under UV light irradiation was achieved in 25 min. The prepared magnetic nano‐photocatalyst can be used in a wide pH range (4–10) for degradation of CV. The effects of scavengers, namely methanol (OH? scavenger), p‐benzoquinone (O2?? scavenger) and disodium ethylenediaminetetraacetate (hole scavenger), on CV photodegradation were investigated.  相似文献   

5.
Photocatalytic reduction/oxidation and deactivation of TiO2 photocatalyst was investigated in the systems composed of Cr(VI) and salicylic acid. The selection of analysis method of Cr(IV) was very important to the monitoring of the photocatalytic process. It was found that as previously reported, serious deactivation of TiO2 catalyst in the simultaneous photo-reduction of Cr(VI) and oxidation of salicylic acid was incorrectly observed if the Cr(VI) level was analyzed by directly monitoring the absorbance at characteristic 348 nm band of Cr(VI), because it seriously suffers from the interferences of the intermediates generated from the degradation of salicylic acid. By using an appropriate method to determine the Cr(VI) concentration, it was observed that all the added Cr(VI) could be reduced, not showing marked deactivation of the photocatalyst. A long time photocatalytic reduction of Cr(VI) under UV illumination induced the deposition of Cr(III) species on the surface of TiO2 particles, which could cause a mild deactivation of the photocatalyst. However, the accompanied oxidation of salicylic acid was demonstrated to depress the deactivation effect of the deposited Cr(III) species on the photocatalytic activity of the TiO2 photocatalyst.  相似文献   

6.
Cerium‐doped titanium dioxide (TiO2) with a hollow fiber structure was successfully prepared using ammonium ceric nitrate and tetrabutyltitanate as precursors and cotton fiber as the template. The effects of cerium (Ce)‐doping on the crystallite sizes, crystal pattern, and optical property of the prepared catalysts were investigated by means of techniques such as scanning electron microscopy (SEM), X‐ray diffraction (XRD), BET surface area, and UV‐vis diffuse absorption spectroscopy. SEM observation showed that the prepared TiO2 fibers possessed fibrous shape inherited from the cotton fiber and had a hollow structure. As confirmed by XRD and UV‐vis diffuse absorption spectroscopy examinations, Ce‐doping restrained the growth of grain size and extended the photoabsorption edge of TiO2 hollow fiber into the visible light region. The present photocatalyst showed higher photocatalytic reactivity in photodegradation of highly concentrated methylene blue (MB) solutions than pure TiO2 under UV and visible light, and the amount of Ce‐doped significantly affected the catalytic property. In the experiment condition, the photocatalytic activity of 0.5 mol% Ce‐doped TiO2 fiber was optimal of all the prepared samples. In addition, the possibility of cyclic usage of the photocatalyst was also confirmed. The material was easily removed by centrifugal separation. Therefore, using the template method and by doping with cerium, TiO2 may hopefully become a low‐energy consuming, high activity and green environmentally friendly catalytic material.  相似文献   

7.
用酸催化溶胶-凝胶法制备了Fe3+掺杂TiO2/凹凸棒(Fe3+-TiO2/ATP)复合光催化剂,对其结构、微观形貌、光吸收性能和可见光下的光催化性能进行了表征。XRD和TEM测试结果表明,Fe3+-TiO2/ATP具有较好的热稳定性,经450 ℃热处理后的ATP晶体结构基本保持不变,锐钛矿TiO2均匀的分布在ATP表面,TiO2颗粒之间无团聚,且平均粒径小于纯TiO2。UV-Vis-DRS测试结果表明,Fe3+的掺杂可明显增强复合光催化剂对可见光的吸收,光响应范围拓展到了整个紫外-可见光区。在可见光下,Fe3+-TiO2/ATP复合光催化剂对亚甲基蓝具有很好的催化降解活性。Fe3+-TiO2/ATP的反应速率常数分别为TiO2/ATP、P25和纯TiO2的1.37、4.83和6.51倍。复合光催化剂的沉降性能优于纯TiO2和P25,易于分离。  相似文献   

8.
The inferior utilization efficiency of light is the main obstacle to the practical application of traditional photocatalysts such as TiO2 and ZnO. In this regard, the development of novel photocatalysts with the capability of harvesting full spectrum light (from ultraviolet (UV) to near-infrared (NIR)) energy is a promising solution for solar energy conversion and environmental remediation. Here, we report the discovery of a single material that can harvest UV, visible (VIS), and NIR radiations to decompose heavy metal contaminants in aqueous solution. Zeolitic imidazolate framework-67 (ZIF-67) rhombic dodecahedrons were synthesized through a facile solution approach and employed in the reduction of Cr(VI) under UV−VIS−NIR pulsed laser irradiation, which was generated from the fundamental, second and third harmonics of Nd:YAG laser, respectively. The nanostructures showed efficient Cr(VI) reduction under UV, VIS and NIR laser irradiation and the measured reduction efficiency (%) was 71.22%, 69.52%, and 40.79%, respectively after 120 min. A possible explanation for the photocatalytic activity in Cr(VI) reduction was proposed. This is the first study of its kind where pulsed laser and ZIF-67 rhombic dodecahedrons capable of harvesting full spectrum light energy have been employed for the removal of Cr(VI) from water. The extraordinary capacity of harvesting full-spectrum light and long-term stability make ZIF-67 a potential photocatalyst for environmental remediation.  相似文献   

9.
A nanoporous polymeric crystalline TiO2 composite (TiO2/PDVB‐MA) has been successfully synthesized through an in situ synthesis method using divinylbenzene (DVB), methacrylic acid (MA) and tetrabutyl titanate. The experimental results showed that TiO2 nanoparticles composed of the mixture phases of anatase and rutile were homogeneously dispersed into the PDVB‐MA support. The TiO2/PDVB‐MA composite was used as photocatalyst for Rhodamine B (RhB), bisphenol A and 2,4,6‐trichlorophenol degradation under visible light irradiation. More interestingly, the excellent photocatalytic performance of the composite was observed with regard to RhB and bisphenol A, which might be ascribed to the synergistic effect between TiO2 nanoparticles and PDVB‐MA. Moreover, TiO2/PDVB‐MA composite could be recycled at least four times in the removal of RhB, suggesting that it is a promising photocatalyst to catalyze the degradation of organic pollutants under visible light irradiation.  相似文献   

10.
Visible‐light‐driven Ag/AgBr/TiO2/activated carbon (AC) composite was prepared by solgel method coupled with photoreduction method. For comparison, TiO2, TiO2/AC, and Ag/AgBr/TiO2 were also synthesized. Their characteristics were analyzed by XRD, SEM‐EDS, TG‐DSC and UV–vis techniques. Photocatalytic activity and antibacterial performance under visible‐light irradiation were investigated by ICP‐AES, ATR‐FT‐IR and spectrophotometry methods using methylene blue and Escherichia coli as target systems, respectively. The results showed that Ag/AgBr was successfully deposited on anatase TiO2/AC surface, and exhibited a distinct light absorption in the visible region. Ag/AgBr/TiO2/AC displayed excellent antibacterial performance both in dark and under visible‐light illumination. The growth of E. coli cell was inhibited in the presence of Ag/AgBr/TiO2/AC in dark. Moreover, upon visible‐light illumination, a significant damage of cell membrane was noticed. Ag/AgBr/TiO2/AC was also shown higher photocatalytic efficiency for methylene blue degradation than those of TiO2, TiO2/AC, and Ag/AgBr/TiO2. This is attributed to the synergetic effect between AC and Ag/AgBr/TiO2, of which AC acts as the role of increasing reaction areas, continuous enriching, and transferring the adsorbed MB molecules to the surface of supported photocatalysts, and the Ag/AgBr/TiO2 acts as a highly active photocatalyst for degrading MB molecules under visible‐light irradiation.  相似文献   

11.
A series of Ag‐enhanced TiO2–x/C composites (Ag/TiO2–x/C composites) with metal‐organic frameworks (MOFs) as precursors were prepared, and their photocatalytic activities were evaluated by the UV‐light driven photodegradation behaviors of methyl blue (MB). The as‐obtained samples were characterized by several techniques such as SEM, XRD, N2‐adsorption, XPS, UV/Vis spectrophotometry and UV/Vis diffuse‐reflectance spectra. The best photocatalytic performance was achieved in Ag/TiO2–x/C composite pyrolyzed at 1000 °C (ATC‐P10) due to rapid capture of electrons caused by silver doping, higher density of TiO2–x lattice oxygen vacancies for better trapping of electrons, and high surface area due to reduction and evaporation of metallic Zn. No obvious deactivation was observed after 10 cycles of UV‐light degradation of MB under the same experimental conditions. This report reveals a new approach to prepare stable and highly efficient UV‐light‐driven photocatalysts for organic pollutants in water.  相似文献   

12.
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   

13.
Titanium dioxides (TiO2) nanoparticles with one-dimensional (1D) geometry, nanorods and nanostripes, were used as photocatalysts to photodegrade Rhodamine B (RhB) under ultraviolet (UV) and visible irradiation. The nanorods catalyst exhibited very interesting photocatalytic properties: under the UV irradiation its catalytic activity was slightly below that of the well-known TiO2 catalyst P25, while under visible light it exhibited a better activity than P25.This fact indicates that the nanorods have a superior ability to utilize less energetic but more abundant visible light. Moreover, the 1D TiO2 nanoparticles can be readily separated from aqueous suspensions by sedimentation after the reaction. With these advantages the 1D TiO2 catalysts have a great potential for environmental applications. Various analytical techniques were employed to characterize TiO2 catalysts and monitor the photocatalytic reaction. It was found that the catalytic performance of the catalysts is greatly dependent on their structures: The superior activity of P25 (consists of anatase and rutile nanocrystals) under UV light results probably from the interfacial interaction between anatase and rutile nanocrystals in this solid, which do not exist in the nanorods (only anatase). The titanate nanostripes (titanate) can absorb UV photons with shorter wavelength only.  相似文献   

14.
Sulfur doped ZnO/TiO2 nanocomposite photocatalysts were synthesized by a facile sol‐gel method. The structure and properties of catalysts were characterized by X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), UV‐vis diffusive reflectance spectroscopy (DRS) and N2 desorption‐adsorption isotherm. The XRD study showed that TiO2 was anatase phase and there was no obvious difference in crystal composition of various S‐ZnO/TiO2. The XPS study showed that the Zn element exists as ZnO and S atoms form SO2?4. The prepared samples had mesoporosity revealed by N2 desorption‐adsorption isotherm result. The degradation of Rhodamine B dye under visible light irradiation was chosen as probe reaction to evaluate the photocatalytic activity of the ZnO/TiO2 nanocomposite. The commercial TiO2 photocatalyst (Degussa P25) was taken as standard photocatalyst to contrast the prepared different photocatalyst in current work. The improvement of the photocatalytic activity of S‐ZnO/TiO2 composite photocatalyst can be attributed to the suitable energetic positions between ZnO and TiO2, the acidity site caused by sulfur doping and the enlargement of the specific area. S‐3.0ZnO/TiO2 exhibited the highest photocatalytic activity under visible light irradiation after Zn amount was optimized, which was 2.6 times higher than P25.  相似文献   

15.
A novel core–shell TiO2@ZnIn2S4composite has been synthesized successfully by a simple and flexible hydrothermal route using TiO2as precursors.The as-synthesized samples were characterized by X-ray diffraction,UV–vis diffuse reflectance spectra and transmission electron microscopy.The photocatalytic properties of samples were tested by degradation of aqueous methylene blue(MB)under visible light irradiation.It was found that the as-synthesized TiO2@ZnIn2S4photocatalyst was more effcient than TiO2and ZnIn2S4in the photocatalytic degradation of MB.Moreover,TEM images confrmed the TiO2@ZnIn2S4nanoparticles possessed a well-proportioned core–shell morphology.  相似文献   

16.
TiO2/EDTA-rich carbon composites exhibits excellent photoreduction of Cr(VI) activity via ligand-to-metal charge transfer process.  相似文献   

17.
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   

18.
A novel and facile method was developed to prepare a visible‐light driven TiO2/Ag‐AgCl@polypyrrole (PPy) photocatalyst with Ag‐AgCl nanoparticles supported on TiO2 nanofibers and covered by a thin PPy shell. During the synthesis, the PPy shell and Ag‐AgCl nanoparticles were prepared simultaneously onto TiO2 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 TiO2/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 TiO2 nanofibers, Ag‐AgCl nanoparticles and the PPy shell. Furthermore, the TiO2/Ag‐AgCl@PPy composite could be easily separated and recycled without obvious reduction in activity.  相似文献   

19.
Tubular bimetal oxysulfide CuMgOS catalyst was prepared using a feasible method at a low process temperature of 95°C. X‐ray diffractometry, X‐ray photoelectron spectrometry, field emission‐scanning electron microscopy, transmission electron microscopy, UV–Vis diffuse reflectance spectroscopy, photoluminescence emission spectrum, and nitrogen adsorption–desorption isotherms were used for CuMgOS characterizations. The CuMgOS reduction activities were investigated through the reduction of heavy metals of Cr (VI), Pb (II) and Hg (II) solutions, and the organic dyes of rhodamine‐B (RhB), methyl orange (MO) and methylene blue (MB) solutions under dark. The results showed that the CuMgOS prepared with an appropriate N2H4 amount for a suitable Cu (I)/Cu (II) ratio exhibited fast reduction activity without adding any reagents, with which the 100 mL Cr (VI), Pb (II) and Hg (II) solutions of 50 ppm were 100% reduced by 20 mg CuMgOS within 4 min, 6 min and 4 min, respectively. The 100 mL RhB, MO and MB solutions of 50 ppm were 100% reduced by 10 mg CuMgOS within 4 min, 5 min and 1 min, respectively, under the existence of NaBH4. CuMgOS displayed excellent chemical stability for the re‐use tests on heavy metal ions and organic dyes. The excellent performance is attributed to CuMgOS bimetal oxysulfide catalyst with active surface reaction centers to interact with reactants, and the carrier hopping between Cu (I) and Cu (II).  相似文献   

20.
Photocatalytic oxidation of methyl orange (MO) and Congo red (CR) as typical model organic contaminants was investigated in aqueous solution within a cooperating Au/TiO2/sepiolite heterostructure system under UV light irradiation. The Au/TiO2/sepiolite composites with a single-crystalline (anatase) framework was synthesized by a facile sol-gel method using titanium tetrachloride as a TiO2 precursor and depositing metal Au on the surface of TiO2 nanostructures via a facile chemical reduction process. The crystal structure, surface area, light adsorption and the photoinduced charge separation rate of the photocatalyst prepared were characterized in detail. As compared with the pristine TiO2, the Au/TiO2/sepiolite hybrid material exhibited good photocatalytic efficiency (90%) for the UV-light photooxidation of methyl orange, which is four-fold of that of reference TiO2. In addition, Au/TiO2/sepiolite hybrid material also shows a good photodegradation performance toward Congo red removal. The highly efficient photocatalytic activity is associated with the strong adsorption ability of sepiolite for aromatic dye molecules, fast photogenerated charge separation due to the formation of Schottky junction between TiO2 and metallic Au. This work suggests that the combination of the excellent adsorption properties of sepiolite and the efficient separation effect of noble metallic nanoparticles provides a versatile strategy for the synthesis of novel and highly efficient photocatalysts.  相似文献   

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