锶元素改性TiO2／杭锦2#土复合物的光催化性能

以Ti（OBu）4和内蒙古杭锦2^#土为主要原料，Sr（NO3）2为掺杂剂，采用溶胶-凝胶法制备了一系列Sr元素掺杂改性的TiO2／杭锦2^#土复合光催化剂，并用X射线衍射、傅立叶红外光谱和扫描电子显微镜等对样品进行了表征。紫外光照射下，以亚甲基蓝水溶液为光降解体系，考察了Sr的掺杂量和热处理温度对光降解率的影响，结果表明，Sr的掺杂量为0．5％，焙烧温度为500℃条件下制得复合物的催化活性明显优于相同条件下的TiO2／杭锦2^#土。该复合物催化剂的优点是易于从分散体系中分离和可循环使用。     

Direct formation of reusable TiO2/CoFe2O4 heterogeneous photocatalytic fibers via two-spinneret electrospinning

A reusable photocatalytic TiO2/CoFe2O4 composite nanofiber was directly formed by using a vertical two-spinneret electrospinning process and sol-gel method, followed by heat treatment at 550 degrees C for 2 h. The high photocatalytic activity of the composite nanofibers depends on the good morphology of the fibers and the appropriate calcination temperature. The crystal structure and magnetic properties of the fibers were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersion spectroscopy (EDS), transmission electron microscope (TEM) and vibrating sample magnetometer (VSM). The photocatalytic activity of the TiO2/CoFe2O4 fibers was investigated through ultraviolet-visible absorbance following the photo-oxidative decomposition of phenol. Meanwhile, the presence of CoFe2O4 not only broadens the response region of visible light, but also enhances the absorbance of UV light. Furthermore, these fibers displayed photocatalytic activity associated with magnetic activity of CoFe2O4 ferrites, allowing easy separated of the photocatalysts after the photo-oxidative process and effectively avoided the secondary pollution of the treated water.     

Fabrication characterization and activity of a solar light driven photocatalyst: cerium doped TiO2 magnetic nanofibers

A novel magnetic separable composite photocatalytic nanofiber consisting of TiO2 as the major phase, CeO(2-y) and CoFe2O4 as the dopant phase was prepared by sol-gel method and electrospinning technique, and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectrum (UV-vis DRS) and vibrating sample magnetometer (VSM). The photocatalytic activity of the resultant CoFe2O4-TiO2 and CeO(2-y)/CoFe2O4-TiO2 nanofibers was evaluated by photodegradation of methylene blue (MB) in an aqueous solution under xenon lamp (the irradiation spectrum energy distribution is similar to sunlight) irradiation in a photochemical reactor. The results showed that the dopant of Ce could affect the absorbance ability and photo-response range. The sample containing 1.0 wt% CeO(2-y) exhibited the highest degradation with 35% for MB under simulate solar light irradiation. Furthermore, the as-synthesized composite photocatalytic nanofibers could be separated easily by an external magnetic field, thus it might hold potential for application in wastewater treatment.     

Ag/TiO2薄膜结构和光催化性能研究

采用溶胶-凝胶技术制备了Ag掺杂的TiO2薄膜.用XRD、氮吸附法、UV-VIS-NIR分光光度计以及XPS对Ag掺杂后TiO2薄膜结构的变化进行了分析;用分光光学法通过在紫外光照下分解亚甲基蓝的实验比较了TiO2薄膜与Ag/TiO2薄膜的光催化性能.结果发现,掺杂适量的Ag有助于TiO2薄膜光催化氧化性能的提高,原因在于:（1）Ag通过引入耗尽层提高了TiO2的电荷分离能力,并吸引空穴向薄膜表面移动,结果使薄膜表面空穴的浓度提高,薄膜光催化效率提高;（2）Ag减小了TiO2粒子的粒径,使TiO2禁带宽度增大,薄膜光催化氧化的能力提高;（3）Ag掺杂后,TiO2薄膜表面对-OH基和水的吸附增加,使光照后TiO2薄膜表面活性自由基·OH的浓度增加,空穴向薄膜所吸附物质的转移能力提高.     

Effects of mineral tourmaline particles on the photocatalytic activity of TiO2 thin films

Titania composite thin films (T/TiO2) containing tourmaline particles were prepared by a sol-gel method, using alkoxide solutions as precursor. The tourmaline particles and thin films were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and so on. The effects of tourmaline on the photocatalytic activity of TiO2 were measured with methyl orange as an objective photodegradation substance. The results showed that the photocatalytic degradation of methyl orange conformed to the first-order kinetic equation and the composite thin films had better photocatalytic activity due to the cooperation of polarity and the far infrared emission of tourmaline. The T/TiO2 thin films including 0.5 wt% tourmaline exhibited better photocatalytic activity when heat-treated at 250 degrees C for 3 h, than pure TiO2 thin films under the ultraviolet irradiation.     

TiO2 and SnO2 magnetic nanocomposites: influence of semiconductors and synthetic methods on photoactivity

A number of reports have been published on use of TiO2 in thin films, magnetic nanocomposites, or heterostructures such as TiO2/Ag and TiO2/SnO2, as catalysts for water decontamination. Hence, semiconductor materials such as SnO2, associated with TiO2 in such nanocomposites, should be assessed in depth for such applications, especially those involving complex structures, such as magnetic photocatalytic nanocomposites. The present study describes the synthesis, characterization and testing of the photocatalytic potential of TiO2 or SnO2 magnetic nanocomposites obtained by the polymeric precursor and the hydrolytic sol-gel methods. The nanocomposites TiO2/CoFe2O4 and SnO2/CoFe2O4 were synthesized from polymeric precursors while TiO2/Fe3O4 and SnO2/Fe3O4 were synthesized by the hydrolytic sol-gel method. The materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (FEG/SEM) and transmission electron microscopy (TEM). The photocatalytic potentials were evaluated by rhodamine B dye photodegradation under UV-C radiation. Compared to SnO2, the nanocomposites with a coating of TiO2 were found to show better photocatalytic activity, but the SnO2 magnetic nanocomposites showed some photocatalytic activity, even though SnO2 is reported to be inactive for these purposes. As for the synthesis method, the nanocomposites obtained from polymeric precursors had smaller surface areas, but higher photocatalytic activity, than those obtained by the hydrolytic sol-gel method. This observation was attributed to the higher crystallinity and a more active surface resulting from calcination of the polymeric precursor material.     

TiO2 nanotubes/MWCNTs nanocomposite photocatalysts: synthesis, characterization and photocatalytic hydrogen evolution under UV-vis light illumination

Nanocomposite of TiO2 nanotubes (TiO2NTs) and multiwalled carbon nanotubes (MWCNTs) has been synthesized by a hydrothermal method and firstly used in photocatalytic hydrogen production. The obtained TiO2 NTs/MWCNTs composites were characterized by X-ray diffraction, transmission electron microscopy, Raman spectrum and ultraviolet-visible diffuse reflectance spectroscopy. The experimental results revealed that the MWCNTs were decorated with well dispersed anatase TiO2 nanotubes with a diameter of 8-15 nm. A slight blue shift and weak symmetry was observed for the strongest Raman peak which resulted from strain gradients originating from interface integration between TiO2 nanotubes and MWCNTs. The photocatalytic activity of the as-prepared samples was evaluated by hydrogen evolution from water splitting using Na2S and Na2SO3 as sacrificial reagents under UV-vis light irradiation. Enhanced photocatalytic activity compared with P25 has been observed for the resulted samples. The nanocomposite with optimized MWCNTs content of 1% displayed a hydrogen production rate of 161 micromol x h(-1) x g(-1). Good photocatalytic stability of the as-synthesized samples was observed as well.     

H(2)O(2)-sensitized TiO(2)/SiO(2) composites with high photocatalytic activity under visible irradiation

TiO(2)/SiO(2) composite photocatalysts were prepared by depositing of TiO(2) onto nano-SiO(2) particles. X-ray diffraction (XRD), transmission electron micrograph (TEM), Raman spectrometer, UV-Vis diffuse reflectance spectroscopy, Fourier transform infrared spectroscopy (FT-IR) were employed to characterize the properties of the synthesized TiO(2)/SiO(2) composites. These results indicated that the products without calcination were amorphous, and calcination could enhance the crystallinity of TiO(2). Increases in the amount of TiO(2) would decrease the dispersion in the composites. H(2)O(2)-sensitized TiO(2)/SiO(2) composite photocatalysts could absorb visible light at wavelength below 550 nm. The photocatalytic activity of as-prepared catalysts was characterized by methyl-orange degradation. The results showed the uncalcined composite photocatalysts with amorphous TiO(2) exhibited higher photocatalytic activity under visible light, and the activity of catalysts with TiO(2) content over 30% decreased with increasing of TiO(2) content. Increases in the calcination temperature and TiO(2) content promote the formation of bulk TiO(2) and result in a decrease in activity.     

四方排列有序Ag/TiO2空心微球的制备及光催化性能

采用低温垂直沉积法制备了聚苯乙烯(PS)胶体模板,由于低温下粒子热运动受到抑制,排列时发生位错,因此模板中存在大面积四方排列结构。然后采用化学镀法、溶胶-凝胶法在PS微球表面依次沉积银纳米粒子、纳米TiO2,最后高温煅烧除去模板制备了四方排列有序Ag/TiO2空心微球。通过扫描电镜(SEM)、X射线衍射(XRD)对样品进行表征。结果表明这种材料很好地保持了模板的四方排列,具有高度有序的纳米结构。选择降解甲基橙溶液来检验样品的光催化性能,并与纳米TiO2薄膜、四方排列TiO2空心微球的光催化性能进行比较,结果表明四方排列Ag/TiO2空心微球具有最佳的光催化性能。这是有序空心纳米结构和银纳米粒子的沉积共同作用的结果。     

Ag掺杂APS改性的TiO2颗粒的制备及其光催化降解作用

为提高Ag/TiO2纳米颗粒的光催化降解作用,采用聚合凝胶工艺路线,以钛酸四丁酯为前驱体,硝酸银为银源,通过向反应体系引入鳌合剂醋酸、表面改性剂γ-氨丙基三乙氧基硅烷(APS)以及还原剂甲醛等添加剂,制备出TiO2粉体及Ag/TiO2纳米复合粉体。利用FT-IR、XRD、TG-DTA、TEM和UV-Vis-NIR等手段对样品进行表征。结果表明,经γ-氨丙基三乙氧基硅烷改性的TiO2颗粒掺Ag后分散性得到改善,粒径约1 nm的Ag颗粒较均匀地分布在10～15 nm TiO2颗粒上;可见光的利用和锐钛矿热稳定性都得到提高;Ag/TiO2纳米颗粒在光照下对甲基橙具有良好的光催化降解效果。     

Ag/ZnO-C nanocomposite-preparation and photocatalytic properties

In this present study, Ag-hybridized ZnO was prepared through a powder-sol method first, then Ag/ZnO-AC (activated carbon) composite was synthesized by a adsorption method using Ag/ZnO and AC as precursors. The structure and morphology of as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectrum (FT-IR), Raman spectra, and diffuse reflectance absorption spectra, respectively. The photocatalytic performances of the prepared catalysts were investigated by photocatalystic degradation of methyl orange. The influences of initial pH value, initial dye concentration and the calcination temperature on the photocatalytic activity of the catalysts were investigated and the results were discussed. Comparing with pure ZnO and ZnO-AC, Ag/ZnO-AC composite showed greatly enhanced photocatalytic activity. The results demonstrate that the hybridization of silver, activated carbon and ZnO can significantly improve the photocatalytic activity of ZnO. This work could provide new insights into the fabrication of noble metal/ZnO-carbon based composites and facilitate their application in environmental protection issues.     

热处理温度对TiO2/SiO2复合气凝胶光催化性能的影响

采用溶胶–凝胶法在常压下经不同温度热处理制备了TiO2/SiO2复合气凝胶光催化剂,利用XRD、TGA和BET等手段对其微观结构进行表征,以甲基橙溶液光催化降解实验评价其光催化性能,研究了热处理温度对TiO2/SiO2复合气凝胶的微观结构及光催化性能影响规律.结果表明:随着热处理温度升高,TiO2/SiO2复合气凝胶中锐钛矿结晶度升高,晶粒尺寸增大,比表面积减小,使TiO2/SiO2复合气凝胶对甲基橙溶液的光催化降解活性呈现先升后降的变化趋势.当热处理温度为700℃左右,紫外光照20 min TiO2/SiO2复合气凝胶对甲基橙溶液的降解率达到95.4%.     

One-pot synthesis of visible-light-driven plasmonic photocatalyst Ag/AgCl in ionic liquid

Plasmonic photocatalyst Ag/AgCl was prepared by in situ hydrothermal method with the contribution of 1-octyl-3-methylimidazolium chloride ([Omim]Cl), in which the [Omim]Cl ionic liquid acted not only as a precursor but also as a reducing reagent in the process of formation of Ag?. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), and thermogravimetric and differential scanning calorimetry (TG-DSC). The photocatalytic activity of the composites were evaluated by degradation of methyl orange (MO) under visible light irradiation. The experimental results showed that the high activity and stability of Ag/AgCl photocatalysts under visible-light irradiation were due to their localized surface plasmon resonance (LSPR). Based on the characterization of the structure and photocatalytic performance, the LSPR was determined by synergetic effect of many factors, such as particle size of metallic Ag, contents of the Ag? nanoparticles, and the extent of metallic Ag dispersing. A photocatalytic mechanism of the Ag/AgCl photocatalyst was also proposed.     

Growth and characterization of flower-like Ag/ZnO heterostructure composites with enhanced photocatalytic performance

Flower-like Ag/ZnO heterostructure composites were prepared through a solvothermal method without surfactants or templates. The products were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, and photoluminescence (PL) spectroscopy. Results demonstrate that flower-like Ag/ZnO heterostructure composites were composed of wurtzite ZnO flowers coated by face-center-cubic Ag nanoparticles. The growth process of flower-like ZnO crystals was investigated, and a possible growth mechanism was proposed. The photocatalytic activity of the as-prepared flower-like Ag/ZnO samples, pure ZnO samples, and commercial TiO₂ (Degussa, P-25) was tested with the photocatalytic degradation of methylene blue. Results show that the Ag/ZnO heterostructures were superior in photocatalytic activity to the pure ZnO samples and the commercial TiO₂ (Degussa, P-25), but the mixture of Ag (0.1 wt%) particles and ZnO flowers did not, which implies that the heterostructure promoted the separation of photogenerated electron–hole pairs, enhancing the photocatalytic activity. That was primarily verified by the PL results.     

Fabrication and enhanced visible light photocatalytic activity of fluorine doped TiO2 by loaded with Ag

F-doped TiO2 loaded with Ag (Ag/F-TiO2) was prepared by sol-gel process combined with photoreduction method. The physical and chemical properties of the prepared samples were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), high-resolution transmission electron microscope (HRTEM), UV-Vis diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL). XPS analysis indicated Ag species existed as Ag0 in the structure of Ag/F-TiO2 samples. UV-Vis diffuse reflectance spectra showed that the light absorption of Ag/F-TiO2 in the visible region had a significant enhancement compared with the F-doped TiO2 (F-TiO2). PL analysis indicated that the electron-hole recombination rate had been effectively inhibited when Ag loaded on the surface of F-TiO2. The photocatalytic activities of the samples were evaluated for the degradation of X-3B (Reactive Brilliant Red dye, C.I. reactive red 2) under visible light (lambda > 420 nm) irradiation. Compared with F-TiO2, the sample of 0.50 Ag/F-TiO2 showed the highest photocatalytic activity. The interaction between F species and metallic Ag was responsible for improving the visible light photocatalytic activity.     

高能球磨和溶胶凝胶制备碳纳米管掺杂TiO2复合粉及其性能

采用高能球磨法和溶胶-凝胶方法制备了碳纳米管掺杂的Ti02纳米复合粉体,通过扫描电子显微镜、X射线衍射、紫外分光光度计等方法对比分析了复合粉体的形貌、微观结构以及光催化活性.实验结果表明,5％碳纳米管掺杂的Ti02复合粉体的光催化活性得到了有效提高,其中高能球磨法制备的复合粉体颗粒细小、分布均匀,具有更好的光催化活性和...     

Nanofibrous TiO2-core/conjugated polymer-sheath composites: synthesis, structural properties and photocatalytic activity

Nanofibrous TiO2-core/conjugated polymer-sheath composite nanocables were synthesized by in-situ chemical oxidative polymerization of aniline with oxidant in the presence of TiO, nanofibers prepared through an electrospinning process. During the polymerization process, aniline molecules were adsorbed on the surface of TiO2. Upon the addition of oxidant, the polymerization of aniline takes place on the surface of the TiO2 nanofibers and polyaniline (PANI) is gradually deposited on their surface. The resulting TiO2-PANI nanocomposites have a coaxial nanocable structure. The morphological and structural properties of the composite nanocables were analyzed by using high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) and UV-visible spectroscopy (UV-vis), respectively. The HRTEM images proved that PANI (20 nm thickness) covered the surface of the TiO2 nanofibers. Also, the photocatalytic activity for the degradation of organic dyes on fibrous photocatalysts under UV-light was studied. The photocatalytic experiments showed that dye could be degraded more efficiently on the TiO2-PANI composite nanocables than on pure TiO2, due to the charge transfer from PANI to TiO2. The method for the synthesis of these unique structured composite nanocables is simple, rapid and reproducible. This facile method may be developed to produce multifunctional nanocomposites of various polymers with metal oxide fibers on a large scale for various technological applications such as sensors, solar cells, and catalysts.     

纳米Ag包覆Bi_2O_3颗粒的制备及其可见光催化性能评价

本文采用两步合成工艺,通过化学共沉淀工艺制备β-Bi_2O_3纳米颗粒;经室温原位还原硝酸银,制备不同包覆量纳米Ag负载的Bi_2O_3(Ag/β-Bi_2O_3)光催化剂颗粒。对该光催化剂进行结构表征,并以甲基橙溶液模拟废水在可见光下评价其光催化性能。透射电子显微镜(TEM)测试表明纳米Ag均匀包覆于β-Bi_2O_3颗粒表面,其中β-Bi_2O_3聚集体的颗粒尺寸约30nm,而分散的纳米Ag晶体约为20nm。紫外可见光谱(UV-vis)谱图表明Ag/β-Bi_2O_3复合材料的带隙能比纯相Bi_2O_3要小,对可见光利用率相应增加,光催化性能随之增强。其中以2.0%(质量比)Ag包覆β-Bi_2O_3颗粒的光催化性能最佳。     

g-C3N4/Ag/TiO2 NTs的制备及其对西维因的光催化降解

采用阳极氧化法制备二氧化钛纳米管(TiO₂ NTs),然后在紫外光和微波辅助下引入Ag、g-C₃N₄制备出g-C₃N₄/Ag/TiO₂ NTs三元复合光催化材料。用扫描电镜(SEM)、X-射线衍射(XRD)、X-射线光电子能谱(XPS)、紫外-可见漫反射光谱(UV-Vis)、光致发光(PL)等手段对g-C₃N₄/Ag/TiO₂ NTs进行表征,研究了这种材料对西维因的降解性能。结果表明,在模拟太阳光照射下,g-C₃N₄/Ag/TiO₂ NTs对西维因的降解率由TiO₂ NTs的29.1%提高到51.8%。光催化活性的提高,与Ag表面等离子体共振效应、Ag优异的电荷传导性以及g-C₃N₄与TiO₂ NTs界面的异质结有关。     

TiO2/活性炭复合体超临界沉淀法制备及其光催化性能

以活性炭为载体、超临界二氧化碳为流体、钛酸丁酯为前驱体,用超临界流体沉积法制备TiO2/活性炭（TiO2/AC）复合体。用X射线衍射（XRD）、扫描电镜（SEM）、比表面积分析（BET）、热重-差热（TG-DTA）对TiO2/AC进行表征。以紫外灯为光源,偶氮类染料亚甲基蓝为标准降解物,考察TiO2/AC复合体的光催化...