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1.
Carbon‐doped TiO2 nanomaterials have been successfully synthesized via an effective two‐step procedure involving hydrothermal method and followed by a low‐temperature calcination treatment process, through which a controllable amount of carbonate‐like species could be incorporated into TiO2. First‐principles calculations suggest the TiO2 doped with carbon in form of carbonate‐like species can effectively extend the adsorption of the material from ultraviolet region to visible light. And it is experimentally found that carbon‐doped TiO2 nanomaterials exhibit much higher photocatalytic activity than reference P25 and TiO2?xNx catalysts toward the liquid‐phase degradation of organic pollutants under visible light (420 nm < λ < 800 nm) irradiation. The presence of synergic effect between carbonate‐like doping and anatase TiO2 is believed to play an essential role in affecting the photocatalytic reactivity, and the response to the visible light is ascribed to the narrowed band gap energy controlled by carbon doping. Moreover, the roles of active species in the photocatalytic process are compared using different types of active species scavengers. Meanwhile, the degradation mechanism of the photocatalysis is proposed. It is hoped that our work could provide valuable information on the design of carbonate‐like doped semiconductor with more excellent properties and set the foundation for the further industrial application.  相似文献   

2.
BACKGROUND: Semiconductor TiO2 has been investigated extensively due to its chemical stability, nontoxicity and inexpensiveness. However, the wide band gap of anatase TiO2 (about 3.2 eV) only allows it to absorb UV light. TiO2 nanoparticles modified by conditional conjugated polymers show excellent photocatalytic activity under visible light. However, these conjugated polymers are not only expensive, but also difficult to process. Polyvinyl chloride (PVC) was heat‐treated at high temperature to remove HCl and a C?C conjugated chain structure was obtained. When TiO2 nanoparticles were dispersed into the conjugated polymer film derived from PVC, this composites film exhibited high visible light photocatalytic activity. RESULTS: The photocatalytic activity of TiO2/heat‐treated PVC (HTPVC) film was investigated by degrading Rhodamine B (RhB) under visible light irradiation. The photodegradation of RhB follows apparent first‐order kinetics. The rate constants of RhB photodegradation in the presence of the TiO2/HTPVC films with different mass content of TiO2 are 16–56 and 4–14 times that obtained in the presence of the pure HTPVC and TiO2/polymethyl methacrylate (PMMA) composite film, respectively. The TiO2/HTPVC film showed excellent photocatalytic activity and stability after 10 cycles under visible light irradiation. CONCLUSION: TiO2/HTPVC film exhibits high visible light photocatalytic activity and stability. Copyright © 2012 Society of Chemical Industry  相似文献   

3.
BACKGROUND: Unlike many water pollution applications, visible‐light‐driven photocatalysis of gas‐phase pollutants has been reported only rarely. The present study was performed to investigate the feasibility of applying S‐doped visible‐light‐induced TiO2 to treat gas‐phase aromatic hydrocarbons, using a continuous air‐flow annular‐type reactor. RESULTS: The prepared S‐enhanced TiO2 powders, along with a commercially available TiO2 powder (Degussa P‐25), were characterized using diffuse reflectance UV‐VIS‐NIR spectrophotometry, Fourier transform infrared (FTIR) spectrophotometry, X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermogravimetry (TG) analyses. A photocatalytic activity test exhibited an increasing trend in degradation reaction rates with increase in flow rate but a decreasing trend in terms of degradation efficiencies. Several experimental conditions induced reasonably high decomposition efficiencies with respect to toluene, ethyl benzene and o,m,p‐xylenes (close to or above 90%), although benzene exhibited a somewhat lower decomposition efficiency. CONCLUSIONS: The S‐doped TiO2 and undoped P25 TiO2 powders exhibited different catalyst characteristics. The results demonstrate that an annular‐type reactor coated with visible‐light‐activated S‐doped TiO2 can serve as an effective tool to treat gas‐phase aromatic hydrocarbon streams. Copyright © 2009 Society of Chemical Industry  相似文献   

4.
Indium (2.9, 3.5, and 4.9 at. %)‐doped and pristine monoclinic BiVO4 nanoparticles were synthesized by hydrothermal method. They were characterized by high‐resolution scanning electron, field emission scanning electron, transmission electron and high‐resolution transmission electron microscopies, powder X‐ray and selected‐area electron diffractometries, energy‐dispersive X‐ray, Raman, UV‐visible diffuse reflectance, photoluminescence, and solid‐state impedance spectroscopies. The band gap and near‐band‐gap emission of 4.9% In‐doped BiVO4 nanoparticles are larger than those of the rest of the nanomaterials. The charge‐transfer resistance of 4.9% In‐doped BiVO4 is the least. In‐doping enhances visible‐light photocatalytic activity.  相似文献   

5.
The main purpose of study was to provide a common synergy using Ag+‐doped calcium phosphate powder and high‐temperature‐stable TiO2 for antibacterial and photocatalytic tile applications. Thermally stable SiO2‐modified TiO2 active layer was deposited on Ag+‐activated ceramic tiles by spray coating. The results showed that a nearly 100% cleanability degree was detected for SiO2‐modified TiO2 (TS)‐coated antibacterial tiles when compared uncoated and unmodified TiO2‐coated tiles. Antibacterial tests and colorimetric analyses indicated that ceramic tiles provide both antibacterial and photocatalytic properties simultaneously.  相似文献   

6.
Transition metal doping into the TiO2 lattice can expand the response of these metal oxide nano particles to the visible region. In view of this, Mo6+ ion is doped into the TiO2 lattice in order to understand the mechanism of its photo response. The prepared photocatalysts were characterized by X-ray diffraction, UV–Visible absorption spectroscopy, UV–Visible diffuse reflectance spectroscopy, SEM, EDX, FTIR and BET specific surface area techniques. The characterization results have confirmed the incorporation of metal ions into TiO2 lattice. XRD analysis shows no change in crystal structure except a slight variation in crystallite size and elongation along the c-axis with increase in the concentration of the dopant. Diffuse reflectance measurements showed a shift in the band edge position to longer wavelengths and an extension of the absorption to the visible region. The photo degradation efficiencies of these catalysts were studied with Tebuconazole pesticide as model pollutant. Under UV light, undoped catalyst showed higher activity than doped catalyst. But in the case of visible light irradiation Mo doped TiO2 with intermediate dopant concentration of 0.06 atom % had the highest photocatalytic reactivity. This may be due to the narrowing of band gap so that it could effectively absorb the light of longer wavelength. The degradation path way was followed by UV–Visible spectroscopy.  相似文献   

7.
A novel visible‐light‐driven photocatalyst of Mo‐doped LiInO2 nanocomposite was successfully synthesized through a sol‐gel method. The effect of Mo‐doping concentrations on the microstructures and properties of LiInO2 was characterized by X‐ray diffraction, scanning electron microscope, X‐ray photoelectron spectroscopy, photoluminescence, and ultraviolet‐visible absorption spectra. The photocatalytic properties of the as‐prepared samples were evaluated by the photocatalytic degradation of methylene blue (MB) dye under visible‐light irradiation. The results demonstrated that the photocatalytic activity of 6% Mo‐LiInO2 reached to 98.6%, which was much higher than that of the undoped photocatalyst LiInO2 (only 46.8%). The enhanced photocatalytic activity is ascribed to Mo‐doping strategy. The holes play an important role in the process of the photodegradation of MB. The superior photocatalytic activity of the as‐prepared Mo‐LiInO2 nanocomposites suggests a potential application for organic dye degradation of wastewater remediation. This work provides a further understanding on tailoring the band structure of semiconductor photocatalyst for enhancing visible‐light absorption and promoting electron‐hole separation by Mo‐doping strategy.  相似文献   

8.
BACKGROUND: The aim of this study was to investigate improvement of the photocatalytic activity of visible‐light driven nitrogen‐modified TiO2 (N‐TiO2) powder toward methyl blue (MB) and direct blue‐86 (DB‐86) dyes. The Taguchi method with an L9 orthogonal array was applied to plan the synthesis parameters, i.e. nitrogen sources, nitrogen source concentrations, stirring time and calcined temperatures. 95% confirmation experiments were undertaken to verify the effectiveness of the Taguchi method. RESULTS: All N‐TiO2 photocatalysts were shifted toward the visible light region with the optical band gap (Eg). Nitrogen source concentrations were significant parameters for the photocatalytic decolorization rate constants (k values). In comparison with pure TiO2, the photodecolorization behavior of N‐TiO2 toward DB‐86 was superior with a reaction rate constant of 1.68 × 10?3 min?1, and a 4 h photodecolorization efficiency of 34%. CONCLUSION: The Taguchi method was reported to alter the surface properties of commercial Degussa P25 TiO2, which could then be used as a visible‐light driven photocatalyst. The visible‐light‐driven photocatalyst was investigated to determine material characteristics. Greater photodecolorization of MB and DB‐86 dye pollutants using optimally‐prepared N‐TiO2 under visible light irradiation was successfully obtained. Copyright © 2011 Society of Chemical Industry  相似文献   

9.
《Ceramics International》2017,43(5):3975-3980
The aim of this research is to enhance the photocatalytic activity of TiO2 nanoparticles for the UV–visible light by multiple-doping with Iridium, carbon and nitrogen. The tridoped TiO2 photocatalyst were prepared by wet chemical method, and characterized by X-ray diffraction, Raman spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, ultraviolet-visible light diffuse reflection spectroscopy and room temperature photoluminescence spectroscopy. Besides, the photocatalytic H2 evolution performance of Ir-C-N tridoped TiO2 under UV–visible light irradiation was evaluated. It was found that Ir existed as Ir4+ by substituting Ti in the lattice of TiO2; meanwhile, C and N were also incorporated into the surface of TiO2 nanoparticles in interstitial mode. Meanwhile, Ir-C-N tridoping extended the absorption of TiO2 into the visible light region and narrowed its band gap to ~3.0 eV, resulting in enhanced photocatalytic H2 evolution under UV–visible light irradiation. This could be attributed to narrow band gap and proper electronic structure of TiO2 after Ir-C-N tridoping.  相似文献   

10.
BACKGROUND: Mercury electrodeless discharge lamps (Hg‐EDLs) were used to generate UV radiation when exposed to a microwave field. EDLs were coated with doped TiO2 in the form of thin films containing transition metal ions Mn+ (M = Fe, Co, Ni, V, Cr, Mn, Zr, Ag). Photocatalytic degradation of mono‐chloroacetic acid (MCAA) to HCl, CO2, and H2O, and decomposition of Rhodamine B on the thin films were investigated in detail. RESULTS: Polycrystalline thin doped TiO2 films were prepared by dip‐coating of EDL via a sol–gel method using titanium n‐butoxide, acetylacetone, and a transition metal acetylacetonate. The films were characterized by Raman spectroscopy, UV/Vis absorption spectroscopy, X‐ray photoelectron spectroscopy (XPS), electron microprobe analysis and by atomic force microscopy (AFM). The photocatalytic activity of doped TiO2 films was monitored in the decomposition of Rhodamine B in water. Compared with the pure TiO2 film, the UV/Vis spectra of V, Zr and Ag‐doped TiO2 showed significant absorption in the visible region, and hence the photocatalytic degradation of MCAA had increased. The best apparent degradation rate constant (0.0125 min?1), which was higher than that on the pure TiO2 film by a factor of 1.7, was obtained with the Ag(3%)/TiO2 photocatalyst. The effect of doping level of vanadium acetylacetonate on the photocatalytic efficiency of the V‐doped TiO2 was determined. CONCLUSIONS: Transition metal ion‐doped TiO2 thin films showed significant absorption in the visible region. The metal doped TiO2 photocatalyst (with an appropriate amount of V, Zr and Ag) on the Hg‐EDLs increased the degradation efficiency of MCAA in a microwave field. Copyright © 2009 Society of Chemical Industry  相似文献   

11.
Silver and zirconium co‐doped and mono‐doped titania nanocomposites were synthesized and deposited onto polyacrylonitrile fibers via sol–gel dip‐coating method. The resulted coated‐fibers were characterized by X‐ray diffraction (XRD), scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy, diffuse reflectance spectroscopy, thermogravimetric analysis, and BET surface area measurement. Photocatalytic activity of the TiO2‐coated and TiO2‐doped coated fibers were determined by photomineralization of methylene blue and Eosin Y under UV–vis light. The progress of photodegradation of dyes was monitored by diffuse reflectance spectroscopy. The XRD results of samples indicate that the TiO2, Ag‐TiO2, Zr‐TiO2, and Ag‐Zr‐TiO2 consist of anatase phase. All samples demonstrated photo‐assisted self‐cleaning properties when exposed to UV–vis irradiation. Evaluated by decomposing dyes, photocatalytic activity of Ag–Zr co‐doped TiO2 coated fiber was obviously higher than that of pure TiO2 and mono‐doped TiO2. Our results showed that the synergistic action between the silver and zirconium species in the Ag‐Zr TiO2 nanocomposite is due to both the structural and electronic properties of the photoactive anatase phase. These results clearly indicate that modification of semiconductor photocatalyst by co‐doping process is an effective method for increasing the photocatalytic activity. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013  相似文献   

12.
A phase transformation of micron‐sized TiO2 powder from anatase to rutile was attempted by heat‐treatment in order to generate a new mixed crystal TiO2 with high associated photocatalytic activity. Heat‐treated micron‐sized TiO2 powders at different transition stages were characterized by X‐ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FT‐IR) and transmission electron microscopy (TEM) methods. The tests of photocatalytic activity of the heat‐treated micron‐sized TiO2 powders were conducted by the photocatalytic degradation of Rhodamine B and Acid Red B under visible light irradiation. The results indicate that mixed crystal TiO2 photocatalyst heat‐treated at 400 °C for 60 min shows the highest photocatalytic activity. It can effectively decompose the Rhodamine B and Acid Red B in aqueous solution after 6 h visible light irradiation. A remarkable improvement in photocatalytic activity of TiO2 is caused by the formation of combined rutile–anatase phases and separation of photogenerated electron–hole pairs. Copyright © 2007 Society of Chemical Industry  相似文献   

13.
Anatase TiO2‐modified flower‐like Bi2WO6 nanostructures were prepared by a simple hydrothermal reaction followed by layer‐by‐layer deposition and calcination. The photocatalytic activity was evaluated using Brilliant Red X3B, an anionic azo dye, as the target organic pollutant under UV‐Vis light irradiation. The experiment results showed that the photocatalytic activity of the hybrid increases first and then decreases with increasing loading amount of TiO2. The hybrid coated with four layers of TiO2 (containing 20 wt‐% TiO2) showed the highest photocatalytic activity, which is 10.45 and 3.20 times higher than that of pure Bi2WO6 and TiO2, respectively. The improved photocatalytic performance of TiO2‐modified Bi2WO6 nanostructures could be ascribed to the improved light‐harvesting ability, efficient photo‐generated electron‐hole separation, and enhanced adsorption of the dye. This work may shed light on the design of complex architectures and the exploitation of their potential applications.  相似文献   

14.
In this study, highly effective B-doped, Ni-doped and B–Ni-codoped TiO2 microspheres photocatalysts were directly synthesized via an aerosol-assisted flow synthesis method. The resulting samples were characterized by XRD, SEM, TEM, UV–vis diffuse reflectance spectroscopy, nitrogen adsorption and XPS. The characterizations revealed hollow microspherical structure of the B-doped and B–Ni-codoped TiO2 photocatalysts, while the Ni-doped and undoped TiO2 products consisted of solid microspheres. It was found that the boron dopant was partially embedded into the interstitial TiO2 structure, existing in the form of Ti–O–B structure. The band gap was enlarged after the boron doping. However, both Ni-doped and B–Ni-codoped TiO2 samples showed obvious red shift in their absorption edges because of the Ni doping. The photocatalytic activities of these samples were evaluated on the photocatalytic removal of NO under simulated solar light irradiation. All the aerosol-assisted flow synthesized samples had much higher photocatalytic activities than P25 and the doped TiO2 microspheres exhibited enhanced photocatalytic activity than the undoped counterparts. More interestingly, the B–Ni-codoped TiO2 photocatalyst possessed superior photocatalytic activity to the as-prepared single doped TiO2 products. The enhanced photocatalytic activity was explained and the formation mechanisms of hollow and solid microspheres were also proposed on the basis of characterizations. We think this general method may be easily scaled up for industrial production of highly active microspherical photocatalysts for efficient NO removal under simulated solar light irradiation.  相似文献   

15.
In this study, silver‐ or copper‐doped TiO2–Ce‐, TiO2–La‐, and commercial TiO2 (P25)‐supported catalysts were prepared. The catalysts and supports were characterised by powder X‐ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and nitrogen adsorption studies. UV‐light‐assisted heterogeneous Fenton‐like oxidation of two different‐structure dyes (anionic azo dye Orange II, CI Acid Orange 7 and cationic triphenylmethane dye Crystal Violet, CI Basic Violet 3) was investigated over the catalysts. Higher catalytic activity was observed in the oxidation of Orange II than in the oxidation of Crystal Violet. For both dyes, the TiO2–Ce and TiO2–La‐supported catalysts, which were in the form of anatase only, gave higher photocatalytic activity than the P25‐supported catalysts, which were in the form of anatase and rutile. Complete colour removal was observed during oxidation of Orange II over Cu/TiO2–Ce and Cu/TiO2–La catalysts, whereas the highest degree of decolorisation, 89.3%, was achieved by oxidation of Crystal Violet over Ag/TiO2–Ce. The pH of the solution affected the surface state of the TiO2, thus affecting the photocatalytic degradation of the dyes. The surface area of the catalysts is also a key parameter that influences their photocatalytic activity. It was observed that catalysts having higher surface areas brought about greater dye degradation.  相似文献   

16.
Titanium dioxide ceramic coatings have been used as catalysts in green technologies for water treatment. However, without the presence of a dopant, its photocatalytic activity is limited to the ultraviolet radiation region. The photocatalytic activity and the structural characteristics of undoped and sulfur-doped TiO2 films grown at 400 °C by metallorganic chemical vapor deposition (MOCVD) were studied. The photocatalytic behavior of the films was evaluated by methyl orange dye degradation under visible light. The results suggested the substitution of Ti4+ cations by S6+ ions into TiO2 structure of the doped samples. SO42? groups were observed on the surface. S-TiO2 film exhibited good photocatalytic activity under visible light irradiation, and the luminous intensity strongly influences the photocatalytic behavior of the S-TiO2 films. The results supported the idea that the sulfur-doped TiO2 films grown by MOCVD may be promising catalysts for water treatment under sunlight or visible light bulbs.  相似文献   

17.
Mesoporous titanium dioxide (M‐TiO2) nanoparticles were successfully prepared followed by chemical modification with different contents of polyaniline (PANI/M‐TiO2) and were used to accelerate the photo‐oxidation and biodegradation process of low‐density polyethylene (LDPE) film. The influence of these additives as a pro‐oxidant additive on the accelerated degradation of LDPE was investigated by photocatalytic oxidation under UV light irradiation and biodegradation with fungal strains. It was found that the as‐prepared PANI modified M‐TiO2 particles exhibited an obvious light response from 400 to 800 nm which can improve the utilization of solar light. Compared with M‐TiO2, PANI/M‐TiO2 exhibited better photocatalytic performance when irradiated under UV light and the subsequent biodegradation efficiency was enhanced. Enhancement of the photocatalytic performance of PANI/M‐TiO2 could be attributed to good dispersibility and compatibility of PANI/M‐TiO2 in the LDPE matrix, a narrow band gap, effective separation of photogenerated electron–hole pairs and the chromophoric group of PANI which was used as a photosensitizer in the LDPE/PANI/M‐TiO2 composite film. © 2019 Society of Chemical Industry  相似文献   

18.
Coprecipitation and hydrothermal method were utilized for the synthesis of Co‐doped Ni‐Zn ferrite and barium titanate nanoparticles. The microwave absorption properties of Co‐doped Ni‐Zn ferrite/barium titanate nanocomposites with single layer structure were studied in the frequency range of 8.2–12.4 GHz.The spectroscopic characterizations of the nanocomposites were examined using X‐ ray diffraction, scanning electron microscopy, transmission electron microscopy and dynamic light scattering measurement. Thermogravimetric analysis indicated the high thermal stabilities of the composites. The composite materials showed brilliant microwave absorbing properties in a wide range of frequency in the X‐band region with the minimum return loss of ?42.53 dB at 11.81 GHz when sample thickness was 2 mm and the mechanisms of microwave absorption are happening mainly due to the dielectric loss. Compared with pure Co‐doped Ni‐Zn ferrite, Co‐doped Ni‐Zn ferrite/BaTiO3 composites exhibited enhanced absorbing properties. The microwave absorbing properties can be modulated by controlling the BaTiO3 content of the absorbers and also by changing the sample thicknesses. Therefore, these composites can be used as lightweight and highly effective microwave absorbers. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39926.  相似文献   

19.
A photocatalyst, TiO2?xNy/AC (activated carbon (AC) supported N‐doped TiO2), highly active in both the Vis and UV range, was prepared by calcination of the TiO2 precursor prepared by acid‐catalyzed hydrolysis in an ammonia atmosphere. The powders were characterized by diffuse reflectance spectroscopy, scanning electron microscopy, X‐ray diffraction, N2 adsorption, Fourier transform infrared spectroscopy and phenol degradation. The doped N in the TiO2 crystal lattice creates an electron‐occupied intra‐band gap allowing electron‐hole pair generation under Vis irradiation (500–560 nm). The TiO2?xNy/AC exhibited high levels of activity and the same activity trends for phenol degradation under both Vis and UV irradiation: TiO2?xNy/AC calcined at 500 °C for 4 h exhibited the highest activity. The band‐gap level newly formed by doped N can act as a center for the photo‐generated holes and is beneficial for the UV activity enhancement. The performance of the prepared TiO2?xNy/AC photocatalyst revealed its practical potential in the field of solar photocatalytic degradation of aqueous contaminants. Copyright © 2007 Society of Chemical Industry  相似文献   

20.
Niobium‐doped Titanium dioxide (Nb:TiO2) transparent films were successfully deposited on glass substrates using a non‐aqueous sol‐gel spin coating technique. The effect of Nb concentration on the structural and photocatalytic properties of Nb:TiO2 films was studied using X‐ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and UV visible spectroscopy. The films with 12 at.% (atomic percent) Nb doped TiO2 showed excellent photocatalytic activity through 97.3% degradation of methylene blue (MB) after 2 h of UV irradiation.  相似文献   

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