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1.
Cu and N-doped TiO2 photocatalysts were synthesized from titanium (IV) isopropoxide via a microwave-assisted sol-gel method. The synthesized materials were characterized by X-ray diffraction, UV-vis diffuse reflectance, photoluminescence (PL) spectroscopy, SEM, TEM, FT-IR, Raman spectroscopy, photocurrent measurement technique, and nitrogen adsorption–desorption isotherms. Raman spectra and XRD showed an anatase phase structure. The SEM and TEM images revealed the formation of an almost spheroid mono disperse TiO2 with particle sizes in the range of 9-17 nm. Analysis of N2 isotherm measurements showed that all investigated TiO2 samples have mesoporous structures with high surface areas. The optical absorption edge for the doped TiO2 was significantly shifted to the visible light region. The photocurrent and photocatalytic activity of pure and doped TiO2 were evaluated with the degradation of methyl orange (MO) and methylene blue (MB) solution under both UV and visible light illumination. The doped TiO2 nanoparticles exhibit higher catalytic activity under each of visible light and UV irradiation in contrast to pure TiO2. The photocatalytic activity and photocurrent ability of TiO2 have been enhanced by doping of the titania in the following order: (Cu, N) - codoped TiO2 > N-doped TiO2 > Cu-doped TiO2 > TiO2. COD result for (Cu, N)-codoped TiO2 reveals ∼92% mineralization of the MO dye on six h of visible light irradiation.  相似文献   

2.
N-doped TiO2 photocatalysts were prepared by annealing two different precursors, P25 and a TiO2 xerogel powder under NH3/Ar flow at 500, 550, and 600 °C. The xerogel powder prepared by peptizing Ti(OH)4 with HNO3 was composed of nanoparticles and had large specific surface area. During the annealing process, the xerogel powder underwent increase in crystallinity, grain growth and phase transformation, whereas P25 did not show obvious changes. Compared with the N-doped TiO2 photocatalysts from P25, the N-doped TiO2 photocatalysts from the xerogel powder possessed higher concentrations of the substitutional nitrogen and exhibited more obvious absorption in the visible light region. The N-doped TiO2 photocatalysts from the xerogel powder exhibited obvious visible-light activities for photodegrading methylene blue and the sample prepared at 500 °C achieved the best performance with a rate constant (k) about 0.44 h−1, whereas those from P25 did not exhibit improved visible-light activities.  相似文献   

3.
Using a new nitrogen precursor of a mixture of ammonia and hydrazine hydrate, N-doped TiO2 photocatalyst with a high efficiency under visible light was synthesized by a precipitation method. The analysis of X-ray photoelectron spectroscopy (XPS) suggested that the doping concentration of nitrogen was 0.45 at%, while it was 0.21 at% or 0.24 at% using single ammonia or hydrazine hydrate as nitrogen precursor. The patterns of the electron paramagnetic resonance spectroscopy (EPR) indicated that the paramagnetic species of NO22?, NO and Ti3+ existed as the proposed active species. The ultraviolet–visible (UV–vis) spectra revealed that the band-gap of the N-doped TiO2 was 3.12 eV, which was slightly lower than 3.15 eV of pure TiO2. The N-doped TiO2 showed higher efficiency under both ultraviolet (UV) and visible light irradiations. Moreover, the degradation grade of 4-chlorophenol (4-CP) using the as-synthesized N-doped TiO2 under sunlight irradiation for 6 h was 82.0%, which was higher than 66.2% of the pure TiO2, 60.1% or 65.2% of the N-doped TiO2 using single ammonia or hydrazine hydrate as precursor. Density functional theory (DFT) calculations were performed to investigate the visible light response of the N-doped TiO2. Our study demonstrated that the visible activities vary well with the concentrations of NO22? species incorporated by N–TiO2 series photocatalysts and the higher activity of the as-prepared N-doped TiO2 was attributed to the enhancement of the concentration of NO22? species.  相似文献   

4.
Photocatalytic degradation of glyphosate contaminated in water was investigated. The N‐doped SnO2/TiO2 films were prepared via sol–gel method, and coated on glass fibers by dipping method. The effects of nitrogen doping on coating morphology, physical properties and glyphosate degradation rates were experimentally determined. Main variable was the concentration of nitrogen doping in range 0–40 mol%. Nitrogen doping results in shifting the absorption wavelengths and narrowing the band gap energy those lead to enhancement of photocatalytic performance. The near optimal 20N/SnO2/TiO2 composite thin film exhibited about two‐ and four‐folds of glyphosate degradation rates compared to the undoped SnO2/TiO2 and TiO2 films when photocatalytic treatment were performed under UV and solar irradiations, respectively, due to its narrowest band gap energy (optical absorption wavelength shifting to visible light region) and smallest crystallite size influenced by N‐doping.  相似文献   

5.
The photo-degradation of formaldehyde (HCHO) by nitrogen-doped nanocrystalline TiO2 (N-TiO2) powders under visible light irradiation has been systematically investigated. Experimental results show that the degradation ratio reached up to 42.6% after 2 h visible light irradiation when the amounts of N-TiO2 powders were 0.5 g, the initial concentration of the HCHO was set at 0.98 mg/m3, the illumination intensity was fixed at 10,000 lux, the ambient temperature was set at 26 °C, and the relative humidity was maintained at 33 ± 5%. Further research shows that the degradation ratios were all larger than 40% in ten repeated cycles of photodegradation of HCHO by N-TiO2 powders. The degradation ratio was as high as 82.9% after 2 h visible light irradiation when the amount of N-TiO2 was 5 g. The degradation ratio was increased from 25.5 to 59.6% when the illumination intensity of the visible light was increased from 0 to 30,000 lux. However, the degradation ratio could not be further increased by further increasing the illumination intensity.  相似文献   

6.
Visible-light-driven N-doped TiO2 was prepared by a simple sol–gel process using nitric acid not only as the acid catalyst of the sol–gel reaction but also as the source of nitrogen. The photocatalytic performance of the N-doped TiO2 was investigated by using FTIR spectroscopy to monitor the degradation of trichloroethylene (TCE) during UV and visible irradiation. The photocatalytic degradation of TCE was well-reproduced several times. The activity of Ti–O–N species was supported experimentally. The N-doped TiO2 was found to be responsive to visible light and was stable during repeated runs and maintained the nitrogen species and its activity for at least four months.  相似文献   

7.
Nanocrystalline N-doped TiO2 powders were successfully prepared by hydrothermal reaction for 2 h at low temperature (120 °C) and at an applied pressure of 3 MPa. The grain size of the powders (calculated by use of Scherrer’s method) ranged from 8.2 to 10.2 nm. The BET specific surface area ranged from 151.0 to 220.0 m2/g. A significant shift of the light absorption edge toward the visible light zone was observed in the UV–visible spectra. XPS results showed that nitrogen atoms were incorporated into the TiO2 lattice. The photocatalytic activity of the synthesized N-doped TiO2 powders was evaluated by measurement of photodegradation of methylene blue (MB) in aqueous solution under visible light irradiation. The amount of MB degraded increased with increasing illumination intensity.  相似文献   

8.
Novel ammonia and triethanolamine assisted sol–gel synthesis method was developed to fabricate the N-doped TiO2 hollow spheres. The prepared hollow spheres were in submicron size and had good morphology and high specific surface area. Polystyrene (PS) latexes in size of 470 nm were used as the templates to fabricate PS/TiO2 core–shell spheres. Here ammonia and triethanolamine was first employed together to control the sol–gel process. The N-doped TiO2 hollow spheres were got after calcinations of the core–shell spheres by using triethanolamine as N source, and the amount of doped N could be easily adjusted by changing the amount of triethanolamine. The hollow spheres had distinct visible light response, and the optical response shifted more to the visible region as the amount of doped N increases. The photodegradation of methylene blue expressed the high photocatalytic activity of the N-doped TiO2 hollow spheres under visible light.  相似文献   

9.
The influence of NH3-treating temperature on the visible light photocatalytic activity of N-doped P25-TiO2 as well as the relationship between the surface composition structure of TiO2 and its visible light photocatalytic activity were investigated. The results showed that N-doped P25-TiO2 treated at 600°C had the highest activity. The structure of P25-TiO2 was converted from anatase to rutile at 700°C. Moreover, no N-doping was detected at the surface of P25-TiO2. There was no simply linear relationship between the visible light photocatalytic activity and the concentration of doped nitrogen, and visible light absorption. The visible light photocatalytic activity of N-doped P25-TiO2 was mainly influenced by the synergistic action of the following factors: (i) the formation of the single-electron-trapped oxygen vacancies (denoted as Vo·); (ii) the doped nitrogen on the surface of TiO2; (iii) the anatase TiO2 structure.  相似文献   

10.
氮掺杂TiO2光催化剂的制备及可见光催化性能研究   总被引:7,自引:0,他引:7  
在溶胶-凝胶法基础之上,以尿素为氮源,通过较温和的反应条件来制备氮掺杂TiO2光催化剂。以亚甲基蓝为模型化合物、日光色镝灯为光源,探索了其可见光光催化性能;并用XRD、低温氮气吸附-脱附技术、UV-Vis等表征了其结构特征;同时以对苯二甲酸为探针分子,结合化学荧光技术研究了光催化体系中·OH自由基的变化规律,进一步验证了其光催化活性规律。结果表明:氮掺杂能引起TiO2光催化剂的激发吸收光谱明显红移并具较好的可见光响应性;在不同煅烧温度和尿素/钛酸丁酯物质的量的比  相似文献   

11.
《Arabian Journal of Chemistry》2020,13(11):8347-8360
FeN -co-doped TiO2 photocatalysts are prepared by sol–gel method using titanium tetraisopropoxide, urea and iron(II) acetylacetonate as precursors of titania, nitrogen and iron, respectively. The prepared samples are analysed from chemical-physical point of view by X-ray diffraction (XRD), Raman spectroscopy, UV–Vis diffuse reflectance spectroscopy (UV–Vis DRS), specific surface area measurements and scanning electron microscopy (FESEM). UV–Vis DRS spectra evidence that the co-doping of TiO2 with N and Fe leads to the narrowing of the band gap value (2.7 eV) with respect to Fe-doped TiO2 (2.8 eV) and N-doped TiO2 (2.9–3 eV). XRD patterns show that photocatalysts are mainly in anatase phase and Fe and N ions are successfully incorporated into the TiO2 lattice. The average crystallite size of Fe-N co-doped TiO2 is slightly lower than the other samples and equal to about 7 nm and the specific surface area of the co-doped sample results to be 117 m2 g−1. Photocatalytic performances of all prepared samples are evaluated by analysing the degradation of Acid Orange 7 azo dye under visible light irradiation. Photocatalytic efficiency obtained using FeN co-doped TiO2 strongly increases compared to undoped TiO2, N-doped TiO2 and Fe-doped TiO2 photocatalysts. In detail, using the co-doped photocatalyst, dye discoloration and mineralization result equal to about 90 and 83% after 60 min of LEDs visible light irradiation, underlining the best performances of the FeN co-doped TiO2 photocatalyst both in terms of treatment time and electric energy consumption.  相似文献   

12.
Nitrogen-doped and oxygen-deficient TiO2 microspheres (NT) with large specific surface were prepared by a solvothermal method and following with electron beam (EB) irradiation under various doses (140–500 kGy). XPS results show that under the EB irradiation, nitrogen ions have been doped into the TiO2 lattice successfully, as well as part of Ti4+ on the surface of the samples changed to Ti3+. Photocatalytic performance was tested by decomposing Rhodamine B in the aqueous phase under visible light irradiation. The prepared materials under the EB irradiation at dose of 140 kGy (NT-140) exhibit the best visible light photocatalytic activity. It is attributed to the large specific surface (138.4 m2/g) and a synergistic effect between substitutional nitrogen dopants and oxygen defects in NT-140. The results obtained may provide a new sight for the application of EB-assisted preparation of nanomaterials.  相似文献   

13.
Mn–N-codoped TiO2 nanocrystal photocatalysts responsive to visible light were synthesized for the first time by a simple hydrothermal synthesis method. X-ray powder diffraction (XRD) measurement indicated that all the photocatalysts have an anatase crystallite structure, and that increase of the doping concentration had little effect on the structure and particle size. Compared to N-doped TiO2, a shift of the absorption edge of Mn–N-codoped TiO2 to a lower energy and a stronger absorption in the visible light region were observed. The Mn–N-codoped TiO2 showed higher photocatalytic reactivity than undoped TiO2 or N-doped TiO2 for the photodegradation of rhodamine B (RhB) under visible light irradiation. The highest photocatalytic activity was achieved on 0.4 mol% Mn–N–TiO2 calcined at 673 K.  相似文献   

14.
During chemical vapor synthesis of TiO2 nanopowders, nitrogen atoms were doped into the crystal lattice of TiO2. The nitrogen atoms were predominantly incorporated substitutionally in the crystal lattice of TiO2 nanopowders up to the doping level of 1.25 mol% nitrogen, whereas they were in both interstitial and substitutional sites over about 1.43 mol% nitrogen. From the photocatalytic activity of nitrogen-doped TiO2 estimated by decomposition of methylene blue under visible light, it was found that the substitutional nitrogen anions appearing at the low level doping was beneficial to its photocatalytic activity, whereas the interstitial ones appearing at the high level doping over 1.25 mol% nitrogen were not. The improved photocatalytic activity due to the substitutionally doped nitrogen was attributed to band gap narrowing which was confirmed by the studies of XPS, near edge X-ray absorption fine structure, and UV–Vis absorption.  相似文献   

15.
Nitrogen-doped TiO2 nanoparticle photocatalysts were obtained by an annealing method with gaseous ammonia and nitrogen. The influence of dopant N on the crystal structure was characterized by XRD, XPS, BET, TEM and UV-Vis spectra. The results of XRD indicate that, the crystal phase transforms from anatase to rutile structure gradually with increase of annealing temperature from 300 to 700 ℃. XPS studies indicate that the nitrogen atom enters the TiO2 lattice and occupies the position of oxygen atom. Agglomeration of particles is found in TEM images after annealing. BET results show that the specific surface areas of N-doped samples from 44.61 to 38.27 m2/g are smaller than that of Degussa TiO2. UV-Vis spectra indicate that the absorption threshold shifts gradually with increase of annealing temperature, which shows absorption in the visible region. The influence of annealing condition on the photocatalytic property has been researched over water decomposition to hydrogen, indicating that nitrogen raises the photocatalytic activity for hydrogen evolution, and the modified TiO2 annealed for 2 h at 400 ℃ under gas of NH3/N2 (V/V=1/2) mixture shows better efficiency of hydrogen evolution. Furthermore, the N-doped TiO2 nanoparticle catalysts have obvious visible light activity, evidenced by hydrogen evolution under visible light (λ>400 nm) irradiation. However, the catalytic activity under visible light irradiation is absent for Degussa as reference and the N-doped TiO2 annealed at 700 ℃.  相似文献   

16.
《中国化学会会志》2017,64(11):1333-1339
The degradation of organic dyes in the presence of modified TiO2 is still under intensive investigation. We report here an evaluation of the photocatalytic activity of nitrogen‐ (N‐) and sulfur‐ (S‐) doped TiO2 for the degradation of phenol and methylene blue (MB). N‐doped TiO2 (N–TiO2), S‐doped TiO2 (S–TiO2), and N–S‐doped TiO2 (N–S–TiO2) were prepared using the sol–gel method. The photocatalytic activity was evaluated in a batch reactor using phenol and MB as models of pollutants. In addition, this investigation was performed using a household lamp as the visible light source. Properties of the synthesized materials in terms of Brunauer–Emmett–Teller (BET) surface analysis, field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), and photocatalytic ability were examined. Our study shows that N–S–TiO2 exhibits better photocatalytic degradation ability for all the considered dyes compared to the other doped TiO2 materials. In conclusion, we have successfully prepared and evaluated the photocatalytic activity of N‐ and S‐doped TiO2 for the degradation of phenol and MB using an ordinary household lamp.  相似文献   

17.
A nitrogen doped TiO2/Ni0.5Zn0.5Fe2O4 core–shell structure nanoparticles was prepared by low temperature sol–gel-hydrothermal process. The characterizations of the catalyst indicate that the Ni0.5Zn0.5Fe2O4 nanocrystals of about 25 nm are well-coated with crystalline N-doped titania. The absorption edges in the diffusion reflectance spectra of TiO0.98N1.02 and TiO1.37N0.63/Ni0.5Zn0.5Fe2O4 shift to visible light region. The core–shell nanocatalysts can effectively photodegrade organic pollutants in the dispersion system and can be recycled easily by an external magnetic field.  相似文献   

18.
Nitrogen doped TiO2 represents one of the most promising material for photocatalitic degradation of environmental pollutants with visible light. However, at present, a great deal of activity is devoted to the anatase polymorph while few data about rutile are available. In the present paper we report an experimental characterization of N doped polycrystalline rutile TiO2 prepared via sol-gel synthesis. Nitrogen doping does not affect the valence band to conduction band separation but, generates intra band gap localized states which are responsible of the on set of visible light absorption. The intra band gap states correspond to a nitrogen containing defect similar but not coincident with that recently reported for N doped anatase.  相似文献   

19.
A novel chlorine-doped titanium dioxide catalyst with visible light response was prepared by hydrolysis of tetrabutyl titanate in hydrochloric acid. The catalyst samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS). Results showed that the doped element of Cl lowered the temperatures of phase transformation of TiO2 from amorphous to anatase and from anatase to rutile. The absorption edge of chlorine-doped TiO2 calcined at 300°C shifted to visible light region. X-ray photoelectron spectroscopy results proved that chlorine existed in the TiO2 crystal lattice as anion. The photocatalytic degradation of phenol showed that under visible light (λ > 400 nm) irradiation, the chlorine-doped TiO2 calcined at 300°C displayed the best performance, the degradation ratio of phenol was 42.5% after 120 min. Translated from Chinese Journal of Catalysis, 2006, 27(10): 890–894 [译自: 催化学报]  相似文献   

20.
Nickel, nitrogen-codoped mesoporous TiO2 microspheres (Ni–N–TiO2) with high surface area, and an effective direct band gap energy of ∼2.58 eV. Nickel sulfate used as the Ni source and ammonia gas as the N source here. The efficiency of the as-prepared samples was investigated by monitoring the degradation of Rhodamine B under visible light irradiation. The experimental results indicate that Ni-doped mesoporous TiO2 microspheres show higher photocatalytic activity than mesoporous TiO2 microspheres under visible light irradiation. It mainly due to that the electron trap level (Ni2+/Ni+) promoting the separation of charge carriers and the oxygen vacancies inducing the visible light absorption. In addition, Ni–N–TiO2 shows enhanced activity compared with Ni–TiO2. Codopants and dopants are found to be uniformly distributed in TiO2 matrix. Among the all samples the 0.5% molar quantity of Ni dopant and 500 °C 2 h nitriding condition gives the highest photocatalytic activity. The treatment of ammonia gas on Ni–TiO2 sample induced oxygen vancancies, substitutional and interstitial N. A suitable treatment by ammonia gas also promote separation of charge carriers and the absorption of visible light. The active species generated in the photocatalytic system were also investigated. The strategy presented here gives a promising route towards the development of a metal and non-metal codoped semiconductor materials for applied photocatalysis and related applications.  相似文献   

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