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1.
The Fe3O4/TiO2/Bi2O3 composites were synthesized by a sol–gel method and used as improved photocatalysts for the degradation of methyl orange (MO) under simulated sunlight at room temperature. The as-prepared Fe3O4/TiO2/Bi2O3 composites were characterized by X-ray diffraction, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and diffuse reflectance spectroscopy (DRS). TEM analysis reveals that the composite has a core–shell structure and diameters of Fe3O4 core is about 200 nm. DRS results reveal that all composites showed red shift in optical absorption. TiO2, Fe3O4, and Bi2O3 exist mainly as separate phases in the Fe3O4/TiO2/Bi2O3 composites based on XPS analysis. The photocatalytic degradation of MO with the prepared photocatalysts was studied under simulated sunlight illumination. Photocatalytic reactivity test indicated that the removal efficiency of MO with the Fe3O4/TiO2/Bi2O3 photocatalyst was higher than that of pure TiO2 and Fe3O4/TiO2. Recovery rate of Fe3O4/TiO2/Bi2O3 photocatalysts achieved 80 % after five times reuse.  相似文献   

2.
以钛粉、钽粉为原料,炭黑作为反应性模板,通过熔盐法在炭黑表面原位生长了TaTiC2纳米碳化物涂层,并以所得TaTiC2/C复合物为碳化物前驱体,再经可控氧化制备出中空Ta2O5/TiO2复合光催化剂。采用X射线粉末衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、紫外-可见(UV-Vis)漫反射(DRS)及N2物理吸附等手段对所制备的光催化剂进行形貌、显微结构及孔结构表征。以高压汞灯为紫外光源,以亚甲基蓝为目标降解物,通过光催化降解实验评价中空Ta2O5/TiO2复合光催化剂的光催化活性。结果表明,熔盐法生长碳化物涂层厚度均匀(20~30 nm),碳化物主要以TaTiC2晶相存在且具有纳米级的颗粒尺寸。中空Ta2O5/TiO2复合光催化剂同时具有200 nm左右的中空大孔结构及壳层10 nm左右的介孔结构。中空大孔和介孔的存在提高了所制备催化剂对亚甲基蓝的吸附能力。此外,TiO2与Ta2O5通过电子能带结构的耦合,有效提高了光生电子和空穴的分离效率,从而显著提高了光催化活性。nTinTa=2.5∶1.5时,相应的中空Ta2O5/TiO2复合光催化剂表现出最佳的光催化活性,对亚甲基蓝的紫外光催化降解率高达97%。  相似文献   

3.
以钛粉、钽粉为原料,炭黑作为反应性模板,通过熔盐法在炭黑表面原位生长了TaTiC_2纳米碳化物涂层,并以所得TaTiC_2/C复合物为碳化物前驱体,再经可控氧化制备出中空Ta_2O_5/TiO_2复合光催化剂。采用X射线粉末衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、紫外-可见(UV-Vis)漫反射(DRS)及N2物理吸附等手段对所制备的光催化剂进行形貌、显微结构及孔结构表征。以高压汞灯为紫外光源,以亚甲基蓝为目标降解物,通过光催化降解实验评价中空Ta_2O_5/TiO_2复合光催化剂的光催化活性。结果表明,熔盐法生长碳化物涂层厚度均匀(20~30 nm),碳化物主要以TaTiC_2晶相存在且具有纳米级的颗粒尺寸。中空Ta_2O_5/TiO_2复合光催化剂同时具有200 nm左右的中空大孔结构及壳层10 nm左右的介孔结构。中空大孔和介孔的存在提高了所制备催化剂对亚甲基蓝的吸附能力。此外,TiO_2与Ta2O5通过电子能带结构的耦合,有效提高了光生电子和空穴的分离效率,从而显著提高了光催化活性。nTi∶nTa=2.5∶1.5时,相应的中空Ta_2O_5/TiO_2复合光催化剂表现出最佳的光催化活性,对亚甲基蓝的紫外光催化降解率高达97%。  相似文献   

4.
In this work, the photocatalytic activity of the synthesized graphene oxide (GO)‐Fe3O4/TiO2 mesoporous photocatalysts was evaluated using chlorpyrifos (CP) as a contaminant. The nano‐photocatalyst was characterized by X‐ray diffraction, field emission scanning electron microscopy with energy‐dispersive X‐ray spectroscopy, transmission electron microscopy, and specific surface area by the Brunauer–Emmett–Teller method. Using visible light, the GO‐Fe3O4/TiO2 mesoporous photocatalyst was investigated on the degradation of CP pesticide. The GO‐Fe3O4/TiO2 photocatalyst displayed a good photocatalytic activity, which was achieving 97% of CP degradation after 60 min. Finally, experiments were performed to evaluate GO‐Fe3O4/TiO2 mesoporous nanocatalyst activity on repeated applications; after several uses, its photocatalytic activity was retained, which indicated stability.  相似文献   

5.
《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   

6.
用水热法制备掺镁钛酸钡(Ba1-xMgxTiO3(x=0,0.10,0.20,0.30,0.40),BMT)纳米粉体。运用X射线衍射仪(XRD)、场发射扫描电子显微镜(FESEM)、透射电子显微镜(TEM)、紫外可见漫反射光谱技术(DRS)等手段对样品进行了表征,并在可见光照射下于溶液中考察了其光催化降解甲基橙反应活性。结果表明,通过控制氢氧根浓度可以得到不同形貌的纳米粉体。基于不同条件下制备的样品的微结构分析,提出了这些不同形貌的形成机制。制备出的BMT材料的带隙能约为2.61 eV。光催化反应结果表明BMT的光催化活性比掺氮TiO2高得多。OH-浓度为8 mol·L-1时制备的BMT纳米棒光催化效率最高,经可见光照射360 min,浓度为0.01 mmol·L-1甲基橙溶液的降解率可达到93.0%,且循环使用4次后,其光催化活性并没有明显降低,表明BMT是一种稳定有效的可见光催化剂.  相似文献   

7.
《Comptes Rendus Chimie》2014,17(7-8):818-823
A series of W-modified TiO2 (W–TiO2) photocatalysts were synthesized by a simple sol–gel method. The new photocatalysts were characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–vis-diffuse reflectance spectroscopy (DRS), and Brunauer, Emmett and Teller (BET) surface area analyzer. The photoactivity of the W–TiO2 photocatalysts was evaluated by the photocatalytic oxidation of Congo red (CR) dye. It was found that the average size of the prepared photocatalysts is 10 nm. Moreover, they have high surface areas (∼ 216 m2 g−1) and their light-absorption extends to the visible region compared to pure TiO2. The effects of W-loading and of the calcination temperature of the prepared photocatalysts on their photocatalytic activity were also studied. The obtained results show that the W0.5–TiO2 photocatalyst calcined at 350 °C is much highly photoactive than non-doped or highly doped TiO2. The enhanced photocatalytic activity of the weakly doped TiO2 may be attributed to the increase in the charge separation efficiency and the presence of surface acidity on the W0.5–TiO2 photocatalyst.  相似文献   

8.
Anatase Fe-doped TiO2 films, with the rang of iron to titanium (Fe(NO3)3 · 9H2O:Ti(OC4H9)4)) atomic ratios (R Fe/Ti ) from nominal 0 to 20%, are prepared by a sol-gel drain coating via homemade devices, and the hydrolysis reaction to derive sol is suppressed by adding an new agglomerating agent acetylacetic ether (EAcAc) to the system. The films are characterized by using thermogravimetry and differential thermal analysis (TG-DTA), x-ray diffraction (XRD), ultraviolet (UV)–visible absorbance spectra (UV–vis), and scanning electron microscope (SEM), together with energy-dispersive x-ray spectroscopy (EDX). Furthermore, the photocatalytic activities are measured by photodegrading rhodamine B (RhB) in a cylindrical Pyrex reactor, the experimental details demonstrate that the Fe-doped TiO2 films (R Fe/Ti  = 3.0%) show the most excellent photocatalytic perfomances, which is good accordance with UV-vis spectra.  相似文献   

9.
Recently, environmental disruption is proceeding on a global scale through the consumption of huge amounts of fossil fuels and the emission of various chemical substances. However, these substances resist bio-treatment. TiO2 generates electrons and holes by irradiation with light. Most organic micro-pollutants, including dioxins, are decomposed into carbon dioxide and water by the effect of the holes with high oxidative potential. By using such a photocatalytic reaction, various applications are feasible for environmental cleanup. In general, TiO2 powder has been utilized as photocatalyst, although TiO2 powder photocatalyst has several disadvantages: (1) it is difficult to handle, (2) photocatalytic reaction is slow and it takes a lot of time for treatment and (3) it is difficult to apply to plastics and textiles, because the photocatalyst decomposes them. We have developed a photocatalyst suitable for practical use and have developed high-activity photocatalysts such as TiO2 photocatalytic transparent film, photocatalytic silica-gel, apatite-coated TiO2 photocatalyst usable for plastics and textiles, photocatalytic paper, photocatalytic blue charcoal and photocatalytic oxygen scavenger. The application of these high-activity photocatalysts has been studied in deodorization, anti-bacterial, self-cleaning, anti-stain, water treatment, air purification such as photocatalytic decomposition of dioxins and VOC, and NO x removal. Now various photocatalytic articles using these new photocatalyst materials are on the market in Japan. Photocatalytic technology can create many valuable products for environmental use all over the world.  相似文献   

10.
Surface modification is one important approach to increase the photocatalytic activity of TiO2. By using a modified wet precipitation process, novel M(OH)x/TiO2 nanoparticles were synthesized, where M(OH)x represents ferric or cupric hydroxide. The prepared M(OH)x/TiO2 powders were characterized with XRD, FT-IR, BET, UV–vis DRS, and TGA, and were observed to yield high photocatalytic ability by using methyl orange (MO) as a model compound of organic pollutants to be degraded. Due to the accelerating effects of the new photocatalyst, the half-time of MO during its photocatalytic degradation at pH 6.0 over M(OH)x/TiO2 was decreased from 332 min for unmodified neat TiO2 to 63 min for Fe(OH)3/TiO2 and 65 min for Cu(OH)2/TiO2, respectively. The enhancing effects of M(OH)x/TiO2 was further observed in a wide composition range with various M/Ti atomic ratios in the photocatalysts and in a wide pH range of the MO solution from 3 to 7. This enhancing effect is mainly attributed to the increased trapping of the photogenerated electron by the higher valence sites (Fe(III) or Cu(II)) in the hydroxide layer near the M(OH)x/TiO2 interface and the enriched surface hydroxyl groups which accept photogenerated holes to yield more hydroxyl radicals.  相似文献   

11.
Cerium-doped mesoporous TiO2 nanoparticles with high surface area and thermal stable anatase wall were synthesized via hydrothermal process in a cetyltrimethylammonium bromide (CTAB)/Ti(SO4)2/Ce(NO3)4/H2O system. The obtained materials were characterized by XRD, FESEM, HRTEM, FTIR spectroscopy, nitrogen adsorption and DRS spectra. Experimental results indicated that the doping of cerium not only increased the surface area of mesoporous TiO2 nanoparticles, but also inhibited the mesopores collapse and the anatase-to-rutile phase transformation. Moreover, the undoped, doped anatase mesoporous nanoparticles exhibit higher photocatalytic activity than commercial photocatalyst (Degussa, P25), but the maximum photodegradation rate corresponds to the undoped mesoporous TiO2 nanoparticles. The lower photocatalytic activities of cerium-doped samples compared with undoped one may be ascribed to that the doped cerium partially blocks titania's surface sites available for the photodegradation and absorption of Rhodamine B (RB).  相似文献   

12.
In this work, the Fe-doped mixed crystal TiO2 photocatalyst which can utilize visible light was prepared by sol-gel and heat-treated methods. During heat-treatment, the phase transformation of Fe-doped TiO2 powder occurs and the process is characterized by XRD and TG-DTA technologies. Otherwise, the sizes and shapes of Fe-doped and undoped TiO2 powders were also compared using TEM images. The azo fuchsine in aqueous solutions, as a model compound, was treated under visible light irradiation using Fe-doped mixed crystal TiO2 powders as photocatalyst. The results showed that, under visible light irradiation, the (0.25%) Fe-doped mixed crystal TiO2 powder heat-treated at 600°C for 3.0 h behaved very high photocatalytic activities for degradation of azo fuchsine. The remarkable improvement of the photocatalytic activity of TiO2 powder was elucidated through the cooperative effects of iron doping and phase transformation. The iron doping can restrain the recombination of photogenerated electron-hole pairs and the phase transformation can enhance the absorption of visible light. Furthermore, other influence factors such as azo fuchsine concentration, solution acidity, Fe3+ ion content and irradiation time were also studied. Thus, this method is applicable for the treatment of wastewater.  相似文献   

13.
A Ga2O3–TiO2 photocatalyst was synthesized by a mechanomixing method followed by a sonication technique using different amplitudes of sonication (0%, 25%, 50%, and 75% of 20 kHz). The prepared photocatalysts were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, Fourier-transform infrared, Brunauer–Emmett–Teller (BET) surface area (SBET), zeta potential, and optical techniques. Ga2O3–TiO2 exhibited an excellent photocatalytic activity for Rhodamine B (RhB) dye degradation under UV irradiation. The RhB degradation rate rose linearly with the increase of sonication amplitude. The photodegradation rate (k) of the synthesized samples was calculated according to the Langmuir–Hinshelwood kinetic expression. It reached a maximum of 5.25 × 10−2 min−1 with R2 of 0.99 for Ga2O3–TiO2 (75%) photocatalysts. The main reactive species were detected through radical scavenging experiments. The formation of hole reactive species is the rate-determining step in the case of Ga2O3–TiO2 (75%) photocatalysts.  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.
研究了用一步水热法制备的不同形貌的钛酸铋(Bi4Ti3O12, BIT)粒子的光学和可见光催化性能, 并对其晶体结构和微观结构用X射线衍射(XRD)、场发射扫描电子显微镜(FESEM)、透射电子显微镜(TEM)和高分辨透射电子显微镜(HRTEM)等手段进行了表征. XRD结果表明, 所制备的BIT 样品为层状钙钛矿结构. FESEM结果表明, 通过控制水热过程的反应参数可以得到不同形貌的纳米粒子. 紫外-可见漫反射光谱(UV-Vis DRS)表明BIT 样品的带隙能约为2.88-2.93 eV. 利用可见光(λ>420 nm)照射下的甲基橙(MO)降解实验评价了BIT 样品的光催化性能. 结果表明, BIT 的光催化活性比掺氮TiO2 (N-TiO2)高得多. 研究了形貌对BIT 光催化性能的影响. 所制备的BIT纳米带光催化效率最高, 经可见光照射360 min, 甲基橙溶液的降解率可达到95.0%.  相似文献   

16.
In this paper, magnetic nanocomposites are synthesized by loading reduced graphene oxide (RG) with two components of nanoparticles consisting of titanium dioxide (TiO2) and magnetite (Fe3O4) with varying amounts. The structural and magnetic features of the prepared composite photocatalysts were investigated by powder X-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR), transmission electron microscopy (TEM), UV–vis diffuse reflectance spectra (UV–vis/DRS), Raman and vibrating sample magnetometer (VSM). The resulting TiO2/magnetite reduced graphene oxide (MRGT) composite demonstrated intrinsic visible light photocatalytic activity, on degradation of tartrazine (TZ) dye from a synthetic aqueous solution. Specifically, it exhibits higher photocatalytic activity than magnetite reduced graphene oxide (MRG) and TiO2 nanoparticles. The photocatalytic degradation of TZ dye when using MRG and TiO2 for 3 h under visible light was 35% and 10% respectively, whereas for MRGT it was more than 95%. The higher photocatalytic efficiency of MRGT is due to the existence of reduced graphene oxide and magnetite which enhances the photocatalytic efficiency of the composite in visible light towards the degradation of harmful soluble azo dye (tartrazine).  相似文献   

17.
张旭  杨萍  刘卫华 《分子催化》2020,34(2):133-149
通过调控原料中五水硝酸铋和卤源的比例制备了自掺杂改性Bi_4O_5X_2(X=Br, I)光催化材料,Bi_4O_5X_2(X=Br,I)光催化性能得到明显提升.分别用X射线衍射仪分析催化剂的晶体结构、环境扫描电子显微镜观测催化剂的形貌、紫外可见漫反射分光光度仪测试催化剂的光吸收性能、 ST-MP-9全自动比表面积测试仪测试催化剂的比表面积.通过测定光降解油田污染物丙烯酰胺的吸光度值和化学需氧量(COD)值的变化研究了催化剂的催化活性.结果表明,经过5 h的紫外可见光光降解反应,Bi_4O_5Br_2-Bi2.6降解丙烯酰胺的性能最好,降解率达到58.2%、 COD值降低87.1%.  相似文献   

18.
The activity of many water-splitting photocatalysts could be improved by the use of RhIII–CrIII mixed oxide (Rh2−xCrxO3) particles as cocatalysts. Although further improvement of water-splitting activity could be achieved if the size of the Rh2−xCrxO3 particles was decreased further, it is difficult to load ultrafine (<2 nm) Rh2−xCrxO3 particles onto a photocatalyst by using conventional loading methods. In this study, a new loading method was successfully established and was used to load Rh2−xCrxO3 particles with a size of approximately 1.3 nm and a narrow size distribution onto a BaLa4Ti4O15 photocatalyst. The obtained photocatalyst exhibited an apparent quantum yield of 16 %, which is the highest achieved for BaLa4Ti4O15 to date. Thus, the developed loading technique of Rh2−xCrxO3 particles is extremely effective at improving the activity of the water-splitting photocatalyst BaLa4Ti4O15. This method is expected to be extended to other advanced water-splitting photocatalysts to achieve higher quantum yields.  相似文献   

19.
Ti1–xFexO2 / Fe2O3 (x = 0.3, 0.6, and 0.7 wt%) composites were prepared by solid state reaction of the oxides TiO2 (rutile phase) and Fe2O3 at 550 °C. The following techniques were applied for the characterization of the composites: X‐ray powder diffraction, Mössbauer spectroscopy, SEM, energy dispersive X‐ray spectroscopy and adsorption of nitrogen. The anatase/rutile/hematite ratio and the abundance of Fe3+ were quantified. The results indicate that Fe3+ substituted Ti4+ in the rutile structure and that the α‐Fe2O3 phase was predominantly on the surface of the crystalline Ti1–xFexO2 powders. A substantial increase of the materials density, with respect to rutile, favoured the application of the composites in photocatalytic experiments. The performance of the solids upon the photodegradation of aqueous solutions of carbofuran was evaluated. The Lewis sites created in the composites correlated directly with the photodegradation rate constant of carbofuran and the decrease of the total organic carbon content in the treated solutions. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

20.
TiO2 and Fe-doped TiO2 thin films were prepared on the substrates (glass plates and glass microballs) after dipped in colloid and calcined at 500°C. The films have been characterized by UV-absorption, x-ray diffraction and atomic force microscopy (AFM). The investigated Fe-doped TiO2 (A nominal 10 wt% Fe2O3 was impregnated) thin films were obtained by sol-gel method. The characterization results suggest that the calcined thin films primarily consist of TiO2 anatase. And the light absorption curve of the TiO2 films modified with Fe showed that red shift had happened by the dope of Fe. TiO2/beads as photocatalyst were used to degrade the simulated dyeing water which contains reactive deep-blue dye (K-R). Through the degradation experiment, we found that the dope of Fe promoted the photocatalytic activities. The results showed that the dyeing water can be decomposed more effectively by the photocatalytic oxidation of Fe/TiO2 film on glass micro-balls than glass plates.  相似文献   

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