纳米二氧化钛制备及其有机物定性检测研究

通过牺牲碳球模板合成了内含金核的二氧化钛空心球。这种新颖的核壳结构能够在3分钟内对亚甲基蓝催化降解率达到40％左右，20分钟左右亚甲基蓝催化降解率达到97％左右，可以很好的应用于蒽醌类有机物的快速定性检测，具有良好的应用前景。     

Visible-light photocatalytic activity of SiC hollow spheres prepared by a vapor–solid reaction of carbon spheres and silicon monoxide

SiC hollow spheres are obtained by a vapor–solid reaction using carbon spheres as templates. The prepared SiC hollow spheres are characterized by X-ray diffraction, scanning electron microscopy, nitrogen adsorption, and UV–vis diffuse reflectance spectra. The visible-light photocatalytic activity is evaluated by photocatalytic decomposition of the methylene blue in aqueous solution. Results show that the diameter of SiC hollow spheres ranges from 200 to 300 nm and the shell thickness is about 50 nm. The SiC hollow spheres have a high surface area of 83.5 m²/g and exhibit a mesoporous structure characteristic. The photo-response of the SiC hollow spheres expand to visible-light region with band gap energy of 2.15 eV. The SiC hollow spheres exhibit a significantly enhanced photocatalytic activity due to their high surface area as well as large light-harvesting efficiencies.     

Synthesis and characterization of carbon-doped titania as a visible-light-sensitive photocatalyst

The synthesis and use of carbon-doped TiO₂ particles in photocatalysis under visible light are demonstrated. The carbon-doped titania with its mesoporous structure was prepared by chemical modification and characterized by several techniques including X-ray diffraction, transmission electron spectroscopy (TEM), X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance spectra (EPR), and diffuse reflectance UV-Vis. absorption spectra, with emphasis on the effect of carbon as a doping compound to the titania. Based on EPR data, the photocatalytic activity by visible light can be ascribed to the trapping of electrons at interior sites of the carbon-doped titania between the valence and conduction bands in the titania band structure, and is able to activated by visible light of a wavelength of up to 550 nm. The photocatalytic activity of the carbon-doped TiO₂ nanoparticles was evaluated by examining the decomposition of phenol by irradiation with artificial solar light (>420 nm) and the results were compared with those using Degussa P25, a commercially available titania nanomaterial.     

Photocatalytic activity of titania hollow spheres: Photodecomposition of methylene blue as a target molecule

The submicrometers-sized titania hollow spheres have been synthesized by employing sulfonated-polystyrene latex particles as a template in sol–gel method. The hollow spheres have relatively smooth surface and dense arrangement of titanium dioxide layers. Photocatalytic activity of the hollow spheres was investigated by employing methylene blue (MB) as a target compound. It was observed that the particle size, size distribution, and crystallinity are important factors to get high photocatalytic activity for the decomposition of MB.     

Photocatalytic reduction of Hg using core–shell Fe/CeO2 hollow sphere nanocomposites

A sol–gel method was used to prepare Fe/CeO₂ hollow sphere nanocomposites. For comparison, a direct calcination of cerium nitrate was used to prepare CeO₂ nanoparticles and Fe/CeO₂ nanoparticles. The photocatalytic reduction of Hg was used to study the photocatalytic performance of the prepared nanocomposite photocatalysts using visible-light irradiation. The BET surface areas of the CeO₂ nanoparticles and CeO₂ hollow spheres were 76 and 160 m²/g, respectively. The BET surface area of the hollow sphere CeO₂ and CeO₂ nanoparticles decreased to 145 and 57 m²/g, respectively, by adding iron nanometal. The TEM results revealed that the shapes of the CeO₂ nanoparticle and hollow sphere materials are spherical nanoparticles and uniform nanospheres, respectively. The Fe/CeO₂ nanoparticles and Fe/CeO₂ hollow spheres are spherical nanoparticles and core–shell, respectively. The photocatalytic performance by the Fe/CeO₂ hollow spheres was 50, 3.9, and 1.4 times more efficient than that observed from the CeO₂ nanoparticles, Fe/CeO₂ nanoparticles, and CeO₂ hollow spheres, respectively.     

用水量对溶胶-凝胶法制备氮掺杂纳米二氧化钛的影响

采用两种用水量的溶胶-凝胶工艺制备了氮掺杂二氧化钛(N-TiO2)纳米颗粒粉末,对样品进行了X射线衍射、透射电子显微镜、X射线光电子能谱及紫外-可见漫反射谱分析,并以甲基橙的光催化降解实验研究了样品的可见光催化性能。结果表明:采用用水多的溶胶-凝胶工艺可获得可见光催化活性高的N-TiO2,且N-TiO2的颗粒粒径较小;由于溶胶中过量的N掺杂剂可在N-TiO2前驱体凝胶离心分离时被去除,可进行较低温度的煅烧,易于获得N掺杂浓度较高的N-TiO2。另外,采用用水多的工艺时,氮掺杂剂对TiO2颗粒的氮化及凝胶化过程也有很大的影响,有些含氮化合物作为掺杂剂可能会明显降低N-TiO2的可见光催化活性。     

氧化钨空心球制备及其光催化性能

在较低温度下制备出氧化钨空心球,一方面可以提高催化剂对光源的利用率,另一方面能够降低催化剂成本。以氯化钨为钨源,将其在70 ℃下醇解和水解,于磺化聚苯乙烯微球表面形成氧化钨前驱体纳米颗粒,通过煅烧制备了氧化钨空心球。利用场发射扫描电镜（FE-SEM）、X射线衍射（XRD）、傅里叶变换红外光谱（FT-IR）和综合热分析（TG-DTG）对所制备的产物进行表征。通过光催化降解罗丹明B溶液来测试氧化钨空心球的催化性能,结果表明光照60 min后催化剂对罗丹明B溶液的光催化降解率可达86.61%。     

酵母菌模板组装Ti-Cr二元空心微球及光催化活性

以酵母菌为生物模板制备出了Ti-Cr二元复合空心微球。SEM表明产品粒径为3.5—3.7μm,呈分散较好的圆形,壳壁强度高。X射线衍射表明,TiO2为锐钛矿,Cr2O3为六角形矿。与TiO2相比,UV-V is图谱红移明显,证实Ti-Cr二元复合空心微球对可见光的响应得到加强。FTIR表明,Ti-Cr二元复合空心微球的形式机理可以概括为二步包裹-模板脱除过程。在光催化降解苯胺黑染料废水中,Ti-Cr二元复合空心微球表现出了较高的光催化活性,催化活性增加的原因在于可见光利用率的提高以及Cr3+的掺杂抑制了电子-空穴对的快速复合。     

La掺杂纳米TiO2的制备及光催化性能研究

采用溶胶-凝胶法制备了纯TiO₂和不同La掺杂量的TiO₂纳米粒子，对样品进行了TG-DTA、XRD和UV-Vis 吸收光谱分析，并以染料废水甲基橙为目标降解物，考察了样品的光催化性能。结果发现，La的掺杂抑制了TiO₂粒径的长大，细化了晶粒；La掺入到TiO₂的晶格中，引起了晶格的畸变和膨胀；La的掺杂使TiO₂的吸收带边发生了红移；适量La的掺杂可提高TiO₂的光催化性能。试验条件下，最佳掺杂摩尔分数为0.1％。     

Photocatalytic decomposition of methylene blue using nanocrystalline anatase titania prepared by ultrasonic technique

Nanocrystalline particles of pure anatase titania were prepared by sol–gel method at ambient temperature using ultrasonication (Ti-US). The advantages of ultrasonication method are demonstrated as compared to the conventional stirring method of preparation of titania (Ti-S). The physico-chemical properties of the samples were investigated by powder XRD, SEM, TEM, low temperature (77 K) nitrogen sorption, and UV–Vis spectroscopic techniques. More uniform distribution/dispersion of the nanoparticles (SEM), marginally higher surface area, better thermal stability, and phase purity are some of the advantages of preparation of nanocrystalline titania by ultrasonication method. The UV–Vis diffuse reflectance spectra of the samples prepared by ultrasonication method were blue shifted compared to pure anatase due to decrease in particle size. The behavior of anatase titania in photocatalytic decomposition of methylene blue in aqueous medium was studied as a function of the method of preparation and the crystallite size. The nanoparticles prepared by ultrasonication method were more effective than both, the sample prepared by conventional stirring method and commercial Degussa P-25. The higher photocatalytic activity of Ti-US is attributed to the more uniform size of the particles as compared to Ti-S samples.     

Template-assisted hydrothermal synthesis and photocatalytic activity of novel TiO2 hollow nanostructures

TiO₂ hollow nanostructures were successfully synthesized by a controlled hydrothermal precipitation reaction using Resorcinol–Formaldehyde resin spheres as templates in aqueous solution, and then removal of the RF resins spheres by calcination in air at 450 °C for 4 h. The obtained TiO₂ hollow spheres were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, N₂ adsorption–desorption analysis, and UV–visible diffuse reflectance spectroscopy. The photocatalytic activity of the as-prepared samples was evaluated by photocatalytic decolorization of rhodamine B aqueous solution at ambient temperature under UV illumination. The results indicated TiO₂ hollow nanostructures exhibit the excellent photocatalytic activity probably due to the unique hollow micro-architectures.     

Combined TiO2/SiO2 mesoporous photocatalysts with location and phase controllable TiO2 nanoparticles

Combined TiO₂/SiO₂ mesoporous materials were prepared by deposition of TiO₂ nanoparticles synthesised via the acid-catalysed sol–gel method. In the first synthesis step a titania solution is prepared, by dissolving titaniumtetraisopropoxide in nitric acid. The influences of the initial titaniumtetraisopropoxide concentration and the temperature of dissolving on the final structural properties were investigated. In the second step of the synthesis, the titania nanoparticles were deposited on a silica support. Here, the influence of the temperature during deposition was studied. The depositions were carried out on two different mesoporous silica supports, SBA-15 and MCF, leading to substantial differences in the catalytic and structural properties. The samples were analysed with N₂-sorption, X-ray diffraction (XRD), electron probe microanalysis (EPMA) and transmission electron microscopy (TEM) to obtain structural information, determining the amount of titania, the crystal phase and the location of the titania particles on the mesoporous material (inside or outside the mesoporous channels). The structural differences of the support strongly determine the location of the nanoparticles and the subsequent photocatalytic activity towards the degradation of rhodamine 6G in aqueous solution under UV irradiation.     

Layer-by-layer synthesis of hollow spherical CeO<Subscript>2</Subscript> templated by carbon spheres

CeO₂ hollow spheres were successfully prepared via a layer-by-layer (LBL) method using carbon spheres as sacrificial template and hexamethylenetetramine as precipitating agent. Transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectrum (XPS) were used for their characterization. The obtained products exhibit hollow spherical structure with a diameter of ca. 250 nm as well as the thin shell about ca. 20 nm composed of various oriented polycrystals, and the Brunauer–Emmett–Teller (BET) surface area was measured to be 126 m² g⁻¹. Calcination temperature is found to be crucial to the integrity of the hollow spheres and has to be below 973 K to achieve well defined hollow spheres. CO conversion was used as a catalytic test reaction revealing that the activity of the hollow spherical products was substantially higher than that of the non-hollow counterpart.     

Hydrothermal synthesis of titanium dioxides from peroxotitanate solution using different amine group-containing organics and their photocatalytic activity

Nanosized TiO₂ particles were prepared by hydrothermal method of the amorphous powders which were precipitated in an aqueous peroxotitanate solution using different amine group-containing organics. The physical properties of prepared nanosized TiO₂ particles were investigated. We also examined the activity of TiO₂ particles as a photocatalyst for the decomposition of orange II. The TiO₂ particles calcined at 400 °C were shown to have a stable anatase phase which has no organic compounds. The particles size of titania particles decreased from 15 to 10 nm as the carbon chain length increased. The titania nanoparticles were shown to have a polygonal shape prepared using NH₄OH and tetramethylammonium hydroxide (TMAOH) as additives, however, the micrographs showed the spherical and narrow size distribution prepared using tetraethyl-ammonium hydroxide (TEAOH) and tetrabutylammonium hydroxide (TBAOH). The titania particles prepared using TEAOH as an amine group-containing organic showed the highest activity on the photocatalytic decomposition of orange II. In addition, the titania particles calcined at 500 °C showed the highest activity on the photocatalytic decomposition of orange II.     

TiO2掺杂粉体的溶胶-凝胶和水热合成及其光降解甲醛

为了研究不同掺杂对二氧化钛光化学活性的影响,采用溶胶-凝胶,水热法,由TiOCl2成功制备了掺杂氮原子的二氧化钛样品,并制备了掺杂0.5%(摩尔分数)Fe3 ,Gu2 ,V5 ,Pd2 等金属离子的可见光响应型介孔材料.样品经由X射线衍射,透射电镜,Brunauer-Emmett-Teller(BET)比表面积,Barrett-Joyner-Halenda孔径分布,紫外可见光谱,光电子能谱和荧光光谱等表征;以荧光灯为光源(入射光波长λ≥410 nm),光催化降解甲醛为模式,评价了样品的催化活性.结果表明:掺杂Fe3 ,Cu2 ,V5 ,Pd2 的二氧化钛和单一掺氮的二氧化钛样品的粒径均为10 nm左右,BET比表面积为130 m2/g左右,均为锐钛矿相二氧化钛;Fe/TiO2,Cu/TiO2,V/TiO2,Pd/TiO2和TiO2/N样品的带隙能依次为:2.99,2.93,2.36,2.92 eV和2.87 eV,其在可见光下的光催化降解速率常数分别为:0.006 3,0.008 6,0.004 9,0.003 l/min和0.003 3/min.Cu/TiO2较高的荧光强度和较大的比表面积,导致了其较高的可见光光解活性.     

Microwave-Assisted Synthesis of Titania Nanocubes, Nanospheres and Nanorods for Photocatalytic Dye Degradation

TiO₂ nanostructures with fascinating morphologies like cubes, spheres, and rods were synthesized by a simple microwave irradiation technique. Tuning of different morphologies was achieved by changing the pH and the nature of the medium or the precipitating agent. As-synthesized titania nanostructures were characterized by X-ray diffraction (XRD), UV–visible spectroscopy, infrared spectroscopy (IR), BET surface area, photoluminescence (PL), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and atomic force microscopy (AFM) techniques. Photocatalytic dye degradation studies were conducted using methylene blue under ultraviolet light irradiation. Dye degradation ability for nanocubes was found to be superior to the spheres and the rods and can be attributed to the observed high surface area of nanocubes. As-synthesized titania nanostructures have shown higher photocatalytic activity than the commercial photocatalyst Degussa P25 TiO₂.     

Synthesis of Pd Nanoparticles in La-doped Mesoporous Titania with Polycrystalline Framework

A simple synthetic method to prepare highly dispersed Pd nanoparticles in La-doped mesoporous titania with polycrystalline framework by coassembly and photoreduction is reported. The mesoporous materials were characterized by thermogravimetric (TGA)/differential scanning calorimetric (DSC), low angle and wide angle X-ray diffraction (XRD), transmission electron microscope (TEM), high-resolution transmission electron microscopy (HRTEM) and N₂ adsorption–desorption. The photocatalytic activities of the prepared mesoporous materials were evaluated by the photodegradation of methyl orange.     

A novel mercury-media route to synthesize ZnO hollow microspheres

Zinc oxide (ZnO) hollow microspheres were prepared by templates of surfactant spheres in mercury-media for the first time. Field emission scan electron microscope (FESEM), X-ray diffraction (XRD), infrared spectra (IR) and N₂ adsorption–desorption analysis were used to characterize morphologies and structure features of the products. The obtained ZnO hollow microspheres are amorphous, 1–3 μm in diameter and 70–140 nm in wall thickness. After heat treatment at 500 °C for 2 h, the amorphous ZnO hollow spheres transform to hexagonal wurtzite structure ZnO, and retain hollow sphere morphologies. During the growth of ZnO hollow microspheres, Zn is oxidized at mercury/air interface and the formed ZnO nanoparticles are assembled on the surface of surfactant spheres. PEG plays an important role for the synthesis of ZnO hollow microspheres.     

TiO2 hollow spheres as a novel antibiotic carrier for the direct delivery of gentamicin

The TiO₂ hollow spheres were synthesized using a green, cheap, and easy process, in which carbonaceous spheres were chosen as the removable template. The prepared materials were characterized by X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Energy-dispersive X-ray spectroscopy (EDX), Atomic force microscopy (AFM), Fourier Transform Infrared Spectroscopy (FTIR), and Brunauer–Emmett–Teller (BET) analysis. According to the results, the obtained mesoporous TiO₂ hollow spheres demonstrated an external diameters less than 200?nm with shell thickness around 40?nm. The antibacterial activities of the TiO₂ hollow spheres were evaluated against gram-positive (Bacillus subtilis and Staphylococcus aureus) and gram-negative (Escherichia coli and Pseudomonas aeruginosa). No antibacterial activity was found for TiO₂ hollow spheres in the used concentrations. TiO₂ hollow spheres were loaded with gentamycin as a selected antibiotic to magnify their benefits in biomedical applications. TiO₂ hollow spheres exhibited good antibiotic carrier activity for the direct delivery of gentamicin, which was attributed to interaction between gentamicin and surface due to their larger specific surface area, more abundant porous structure, and their spherical morphology. The application of TiO₂ hollow spheres as gentamicin carrier undoubtedly opens an avenue to use hollow sphere materials in other drug delivery applications.     

铁掺杂二氧化钛空心球的制备及性能

以TiF₄为钛源、九水合硝酸铁为掺杂前体,采用水热法制备铁掺杂的TiO₂空心微球。采用SEM、TEM、XRD、BET、XPS等技术对样品的形貌、结构、晶型、比表面积、元素组成等进行表征,以亚甲基蓝（MB）的光催化降解为目标反应,评价其光催化活性。结果表明,160℃下水热反应生成的纳米TiO₂空心微球晶型为锐钛矿,少量掺铁并不影响微球的形貌及晶体结构。光催化实验表明,160℃下水热反应12 h生成的TiO₂空心微球样品均匀性好、光催化活性最佳;铁掺杂能显著提高TiO₂空心微球的催化活性,当铁钛比为1.5:100时,所得样品粒径最小,比表面积最大,光催化活性最高。