CeO_2/ZnO复合纳米管的制备及其光催化性能的研究

用纳米CeO2掺入ZnO纳米管制备了CeO2/ZnO复合纳米管,考察了复合纳米管的光学及其光催化性能,并运用X射线衍射、透射电镜、比表面积测定和紫外-可见漫反射光谱等技术对样品进行了表征.结果表明,与ZnO纳米管相比,CeO2/ZnO复合纳米管的比表面积虽有所降低,但光催化活性有所提高,随着复合纳米CeO2量的增加,催化剂的光催化活性相应降低,太阳光下CeO2/ZnO复合纳米管对甲基橙溶液也有较高的催化活性.     

Characterization of Pd/TiO2 embedded in multi-walled carbon nanotube catalyst with a high photocatalytic activity

Pd particles loading on TiO₂-embedded multi-walled carbon nanotubes (MWCNTs), MWCNTs, and TiO₂ particles were prepared via an impregnation method with palladium(II) chlorate solution followed by heat treatment at high temperature. To characterize the catalysts, BET surface area, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, energy dispersive X-ray, Fourier transform infrared spectroscopy and ultraviolet-visible spectroscopy were employed. The prepared catalysts were tested in degradation of methyl orange under visible light. Pd/TiO₂-MWCNTs catalyst demonstrates the highest photocatalytic activity, and the phase transformation from PdO to Pd0 phase takes place at heat treatment of embedded TiO₂. The nanoparticles size of TiO₂ can be decreased by introduction of MWCNTs species. Combining structural characterization with kinetic study results we could conclude that the superior catalytic performance could arise due to the Pd/TiO₂-MWCNTs catalyst’s structure.     

浸渍-分解法制备高可见光催化活性的Bi2O3/TiO2纳米管阵列

用浸渍-分解法将Bi₂O₃纳米颗粒沉积在TiO₂纳米管壁上, 制备了Bi₂O₃/TiO₂纳米管阵列. 用电感耦合等离子体发射光谱(ICP-AES)测定了Bi₂O₃/TiO₂ 纳米管阵列的化学组分, 利用X 射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)和紫外-可见(UV-Vis)吸收光谱表征了所制备的样品. 通过在可见光下(λ>400 nm)降解甲基橙(MO)水溶液来评价样品的光催化活性. 结果表明, Bi₂O₃纳米颗粒均匀地沉积在TiO₂纳米管中. Bi₂O₃/TiO₂纳米管阵列具有比纯Bi₂O₃膜和N-TiO₂纳米管阵列高得多的可见光催化活性. Bi₂O₃/TiO₂纳米管阵列活性的增强是其强可见光吸收和Bi₂O₃与TiO₂之间形成的异质结的协同作用的结果.     

Synthesis and Characterization of TiO2/YFeO3 and Its Photocatalytic Oxidation of Gaseous Benzene

YFeO₃ was prepared by coprecipitation method and citric acid method, and TiO₂/YFeO₃ heterosystem photocatalysts were synthesized by loading TiO₂ sol on the surface of YFeO₃via sol-gel method. Their photocatalytic activities were evaluated by the decomposition of gaseous benzene under UV light illumination. The prepared photocatalysts were characterized by nitrogen adsorption-desorption, X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV-Vis diffuse reflectance spectroscopy. Results revealed that the heterosystem photocatalysts prepared by coprecipitation method showed higher activity, and the maximum conversion of benzene could reach 44.7% within 180 min. The YFeO₃ samples prepared from coprecipitation method and citric acid method were absolutely in orthorhombic phase. The deposited titania was dispersed on the surface of carrier and a certain interaction existed between TiO₂ and YFeO₃. The two heterosystems photocatalysts had narrow band-gap energies.     

Study on the synthesis of ZnO/K2SO4 composite material by sol–gel method and its photocatalytic properties

A novel photocatalytic composite material ZnO/K₂SO₄ was prepared using sol–gel method. The samples were characterized by means of wide-angle X-ray diffraction, Fourier-transform infrared spectroscopy, and high-resolution scanning electron microscopy. The preliminary experimental results indicated that the as-prepared composite material exhibited good photocatalytic performance in the degradation of methyl orange in aqueous solution. The results indicate that 92.54% of the initial methyl orange was degraded after 30 min of ultraviolet light irradiation by adding 0.15 g ZnO/K₂SO₄ composite material into 50 mL methyl orange solution.     

脉冲沉积制备Cu2O/TiO2纳米管异质结的可见光光催化性能

在用阳极氧化法制备有序排列TiO₂纳米管阵列薄膜的基础上,引入脉冲沉积工艺,成功实现了均匀、弥散分布的Cu₂O纳米颗粒修饰改性TiO₂纳米管阵列,形成Cu₂O/TiO₂ 纳米管异质结复合材料. 利用场发射扫描电镜（FESEM）、场发射透射电镜（FETEM）、X射线衍射（XRD）、X射线光电子能谱（XPS）和紫外-可见漫反射光谱（UV-Vis DRS）对样品进行表征,重点研究了Cu₂O/TiO₂ 纳米管异质结的光电化学特性和对甲基橙（MO）的可见光催化降解性能. 结果表明,Cu₂O纳米颗粒均匀附着在TiO₂纳米管阵列的管口和中部位置,所制备的Cu₂O/TiO₂ 纳米管异质结具有高效的可见光光催化性能;在浓度为0.01 mol·L^-1的CuSO₄溶液中制得的Cu₂O/TiO₂纳米管异质结表现出最好的电化学特性和光催化性能;另外,对Cu₂O纳米颗粒影响光催化活性的机理进行了讨论.     

金红石相TiO2-石墨烯复合材料的制备及其光催化性能

以鳞片石墨为原料, 用改进的Hummers法制备氧化石墨烯(GO), 以异丙醇钛为钛源经一步水热法制备得到金红石相TiO₂-石墨烯复合材料(rGO-TiO₂), 考察了氧化石墨烯用量对复合材料光催化性能的影响. 采用X射线衍射(XRD), 比表面积(BET), 透射电镜(TEM), 扫描电镜(SEM), 拉曼光谱, 紫外-可见(UV-Vis)吸收光谱和荧光光谱(PL)等测试手段对复合材料进行表征. 结果表明: 复合材料中TiO₂为针簇状结构的金红石相, 与石墨烯能够均匀复合; 与纯金红石相TiO₂相比, 复合材料具有较大的比表面积. 研究了该复合材料在紫外光下对罗丹明B 以及可见光下对甲基橙光降解效果. 当氧化石墨烯浓度为0.5 mg·mL^-1时, 制备得到的复合材料rGO-TiO₂具有较好的光催化效果.     

Improved solar-driven photocatalytic performance of BiOI decorated TiO2 benefiting from the separation properties of photo-induced charge carriers

In this work, BiOI decorated TiO₂ photocatalysts were prepared in-situ by a facile hydrothermal method and characterized by X-ray diffraction (XRD), UV/Vis diffuse reflectance spectroscopy, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and surface photovoltage (SPV) spectroscopy. The reactive radicals during the photocatalytic reaction were detected by scavenger experiments. BiOI/TiO₂ composites exhibit higher performance than the pure TiO₂ towards photocatalytic decolorization of methyl orange (MO) aqueous solution, when the molar ratio of Bi/Ti is 2%, the sample has the highest photocatalytic activity. The enhanced photocatalytic performance of BiOI/TiO₂ could be ascribed to the separation properties of photo-induced charge carriers and strong interaction between BiOI and TiO₂. Based on the observations, a Z-scheme charge separation mechanism was proposed.     

Preparation of multisensitive poly (N-isopropylacrylamide-co-acrylic acid)/TiO2 composites for degradation of methyl orange

Composites of poly (N-isopropylacrylamide-co-acrylic acid)/titanium dioxide (TiO₂) have been prepared via UV-initiated free radical polymerization. Fourier transform infrared spectra (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), environmental scanning electron microscope (ESEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) are used to study the composition, structure, and morphology of the as-prepared composites. TiO₂ is found to be successfully encapsulated in the copolymer in spherical shapes with size of 2.5 μm. The thermo- and pH-responsive properties of the composites are observed using dynamic light scattering (DLS). The photocatalytic property of the composites is studied using UV–vis spectrophotometer on the degradation of methyl orange (MO) solution under various pHs and temperatures. Degradation ratio is higher at low pH and increases with increasing temperature above volume phase transition temperature (VPTT).     

Rapid Synthesis of Nanocrystalline TiO2/SnO2 Binary Oxides and Their Photoinduced Decomposition of Methyl Orange

A rapid and simple method, the so-called stearic acid method (SAM) was developed to prepare nanostructured TiO₂/SnO₂ binary oxides by combustion of stearic acid precursors. The preparative process was studied by Fourier transform infrared spectroscopy (FT-IR). During the preparative process, metal precursors were dispersed in stearic acid at molecular level. Microstructure of the samples was investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), BET specific surface area measurement and the results were compared with those obtained by conventional sol-gel method. The photocatalytic decomposition of methyl orange was used as a model system to determine the relative influences of the preparation method and the concentration of SnO₂ on the photocatalytic activities. It was found that preparative methods affected the crystalline structure of TiO₂/SnO₂ powders and the anatase phase of TiO₂ was stabilized by the addition of SnO₂ in SAM. The samples prepared by SAM showed better dispersity, larger specific surface area and the TiO₂/SnO₂ (r=0.15, SAM) catalyst showed higher photocatalytic activity than Degussa P25.     

玻璃微珠/Ag/TiO2可见光催化剂的制备与表征

通过离子交换法将Ag纳米颗粒负载于玻璃微珠的表面及浅表层,并以钛酸四丁酯的乙醇溶液为前驱体,将TiO₂负载于包含银的玻璃微珠表面,制得一种玻璃微珠/Ag/TiO₂复合光催化剂。由于纳米银的表面等离子体吸收效应,该复合光催化剂具有一定的可见光响应特性。利用XRD、SEM对样品进行表征,可发现玻璃微珠表面形成一层均匀多孔的锐钛矿TiO₂,其粒径均在50 nm左右。由漫反射光谱可得出该催化剂具有较强的可见光吸收,并在降解甲基橙溶液的试验中表现出较好的可见光催化活性。     

立方晶型Sb2O3纳米晶的合成及光催化性能

采用沉淀法合成了立方晶型Sb2O3纳米晶,通过X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、紫外-可见漫反射光谱(UV-Vis DRS)和电子自旋共振谱(ESR)等对样品进行了详细的表征。以紫外光光催化降解甲基橙为反应模型评价了样品的光催化性能。结果表明:沉淀法合成的立方晶型Sb2O3纳米晶颗粒小,表现出良好的光催化性能。对立方晶型Sb2O3纳米晶光催化降解甲基橙的原因进行了探讨,并提出了降解甲基橙的反应机理。     

Plasmon-resonance-enhanced visible-light photocatalytic activity of Ag quantum dots/TiO2 microspheres for methyl orange degradation

We successfully prepared Ag quantum dots modified TiO₂ microspheres by facile solvothermal and calcination method. The as-prepared Ag quantum dots/TiO₂ microspheres were characterized by scanning electron microscope, transmission electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy and UV-vis diffuse reflectance spectroscopy. The Ag quantum dots/TiO₂ photocatalyst showed excellent visible light absorption and efficient photocatalytic activity for methyl orange degradation. And the sample with the molar ratio of 0.05 (Ag to Ti) showed the best visible light photocatalytic activity for methyl orange degradation, mainly because of the surface plasmon resonance (SPR) effects of Ag quantum dots to generate electron and hole pairs for enhanced visible light photocatalysis. Finally, possible visible light photocatalytic mechanism of Ag quantum dots/TiO₂ microspheres for methyl orange degradation was proposed in detail.     

室温一步固相反应合成纳米氧化锌的表征、光催化性能及动力学

以七水硫酸锌、氢氧化钠为原料,采用室温一步固相反应合成ZnO纳米粒子,并分别利用X射线衍射分析（XRD）、傅里叶变换红外光谱分析（FTIR）、热重分析（TG）、扫描电子显微分析（SEM）、透射电子显微分析（TEM）、N₂吸附-脱附、紫外可见漫反射光谱分析（UV-Vis DRS）等方法对ZnO纳米粒子进行表征。实验结果表明：不需任何添加剂,室温下可通过一步固相反应合成ZnO纳米粒子,其形成过程首先是ZnSO₄·7H₂O和NaOH充分接触,然后反应形成Zn₄SO₄（OH）₆·5H₂O,最后NaOH的溶解热可使Zn₄SO₄（OH）₆·5H₂O转变为ZnO并逐渐长大形成纳米粒子。同时以甲基橙为降解对象评价了ZnO纳米粒子的光催化活性,实验结果表明：紫外光照射下,该方法合成的ZnO纳米粒子对甲基橙具有较好的光催化活性,且光催化动力学方程符合准一级反应动力学。     

Preparation and Characterization of Room-temperature Ferromagnetic Ni-doped TiO2 Nanobelts

Ni-doped anatase TiO₂ nanobelts (NBs) with different Ni²⁺ contents were simply prepared by combining ion-exchange with hydrothermal treatment. They were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR), and magnetic measurement techniques. The results showed that Ni²⁺ cations doped into the TiO₂ lattice and no metallic nickel clusters or nanoparticles could be found. The magnetic results demonstrated that the prepared Ni-doped TiO₂ samples had complex magnetic mechanism including room-temperature ferromagnetic and paramagnetic behaviors, and with the increase of Ni²⁺ content, the magnetization also increased under the same applied field owing to uniform distribution of Ni²⁺ ions in TiO₂ nanobelts.     

Synthesis, characterization, and catalytic activity of nitrogen and iron(III) co-doped TiO2

The nitrogen and iron(III) co-doped TiO₂ (N–Fe–TiO₂) samples were synthesized via modified sol–gel method by using alkyl amine as both nitrogen source and pore directing agent. Morphologies and properties of the co-doped TiO₂ samples were investigated by X-ray diffraction, Fourier transform infrared spectroscopy, electron spin resonance spectroscopy, UV–Vis spectroscopy, scanning electron microscopy, and transmission electron microscopy. The results showed anatase phase mixed with rutile structure as well as hydroxyl and amine functional groups. The presence of Fe³⁺ in N–Fe–TiO₂ sample was detected at g value of 2.00. In addition, the prepared samples were photocatalytically active for methyl orange degradation under UV light irradiation, but not under visible light.     

Facile synthesis of Cu2O nanocube/polycarbazole composites and their high visible-light photocatalytic properties

Cu₂O nanocube/polycarbazole composites have been prepared by an one-pot solvothermal process using carbazole as a reductant. The polycarbazole layer not only protected and stabilized Cu₂O particles, but also prohibited the recombination of photogenerated electrons-holes pair and facilitated interfacial charge transfer between polycarbazole and Cu₂O. The composition, structure and morphology of the obtained products was systematically studied by X-ray powder diffraction (XRD), Field-emission scanning electron microscopy (FE-SEM), High-resolution transmission electron microscopy (HRTEM), Fourier transformation infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and UV-visible spectrophotometer. Furthermore, the visible-light photocatalytic behavior of the Cu₂O nanocube/polycarbazole composites on the methyl orange was investigated.     

Preparation of TiO2/ZnS core/sheath heterostructure nanotubes via a wet chemical method and their photocatalytic activity

TiO₂/ZnS core/sheath heterostructure nanotubes are prepared via a simple wet chemical method at room temperature. The samples are characterized with transmission electron microscopy (TEM), X-ray diffraction (XRD) and UV-vis absorption spectrum. Their photocatalytic activity for degradation of methyl orange under UV illumination is valuated. It is found that the ZnS layer changes with the concentration of precursors. The photocatalytic activity of the TiO₂/ZnS depends not only on the structure of the support (TiO₂ nanotubes) but also on the specific interaction between ZnS and support.     

Synthesis,Characterization, and Photocatalytic Properties of Ag/TiO2 Composite Nanofibers Prepared by Electrospinning

Ag nanoparticles (Ag NPs) embedded titanium dioxide (TiO₂) nanofibers were fabricated by colloidal sol process, electrospinning, and calcination technique. Calcination of the electrospun nanofibers were heat treated at 600°C for 180 minutes in air atmosphere. X-ray diffraction patterns exhibited that the anatase phase and silver coexisted in the resulted Ag NPs/TiO₂ nanofibers; transmission electron microscopy demonstrated Ag NPs well spread in the porous microstructure of composite fibers. The prepared nanofibers were utilized as photocatalyst for degradation of methyl orange. The degradation rate of methyl orange dye solution containing Ag/TiO₂ composite nanofibers is 99% only after irradiation for 3 hours. It is proposed that these new Ag NPs/TiO₂ composite nanofibers will have potential application in water pollution treatment.      

Preparation and photocatalytic activity of TiO2-coated granular activated carbon composites by a molecular adsorption-deposition method

TiO₂ nanoparticle-coated granular activated carbon (GAC) composite photocatalysts (CPs) were successfully prepared by a molecular adsorption-deposition (MAD) method. The CPs were detected by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), BET surface area and UV-Vis adsorption spectroscopy, and their photoactivity was evaluated by methyl orange (MO) photodegradation. The results show that small-sized TiO₂ nanoparticles were dispersed well, deposited on the surface of GAC, and showed slight blue shift in comparison with pure TiO₂. With the increase in TiO₂ content, the CPs showed band gaps in lower energy, smaller surface areas and the higher content of Ti³⁺ ions. Compared with pure TiO₂ and others CPs samples, CPs-382 sample showed the highest photoactivity due to the optimum TiO₂ content and surface area besides the synergic effect of photocatalytic degradation of TiO₂ and adsorptive property of GAC. In addition, the CPs could be very easily reclaimed, recycled and reused for methyl orange removal while high photoactivity is preserved. Supported by the Natural Science Foundation of Hunan Province (Grant No. 06JJ50150), the Scientific Research Fund of Science and Technology Department of Hunan Province (Grant No. 2007GK3060) and Jishou University (Grant No. JSDXKYZZ200648)