Fabrication and photocatalytic activity of Ag<Subscript>3</Subscript>PO<Subscript>4</Subscript>-TiO<Subscript>2</Subscript> heterostructural nanotube arrays

To extend the absorption capability of TiO₂ into visible light region and inhibit the recombination of photogenerated electrons and holes, we put forward an effective strategy of the coupling of TiO₂ with a suitable semiconductor that possesses a narrow band gap. Meanwhile, Ag₃PO₄-TiO₂ heterostructural nanotube arrays were prepared by the two-step anodic oxidation to obtain the TiO₂ nanotube arrays and then by a deposition-precipitation method to load Ag₃PO₄. The samples were characterized by field emission scanning electron microscopy (FESEM), energy dispersive spectrometry (EDS), X-ray diffraction (XRD), and UV-vis diffuse reflectance spectroscopy (UV-vis DRS). The experimental results showed that Ag₃PO₄ nanoparticles were uniformly dispersed on the highly ordered TiO₂ nanotube arrays, which increased the visible-light absorption of TiO₂ photocatalyst. The photocurrent density and photocatalytic degradation of methyl orange indicated that the performance of Ag₃PO₄-TiO₂ heterostructural nanotube arrays was better than that of the TiO₂ nanotube arrays, which could be attributed to the effective electron-hole separation and the improved utilization of visible light.     

Electrochemical preparation and photoelectric properties of Cu2O-loaded TiO2 nanotube arrays

TiO2 nanotube （TNT） arrays were fabricated by anodic oxidation of titanium foil in a fluoride- based solution, on which Cu20 particles were loaded via galvanostatic pulse electrodeposition in cupric acetate solutions in the absence of any other additives. The structure and optical properties of Cu2O-loaded TiO2 nanotube arrays （Cu2O-TNTs） were analyzed by scanning electron microscopy （SEM）, X-ray diffraction （XRD） and UV-Vis absorption, and the photoelectrochemical performance was measured using an electrochemical work station with a three-electrode configuration. The results show that the Cu2O particles distribute uniformly on the highly ordered anatase TiO2 nanotube arrays. The morphologies of Cu2O crystals change from branched, truncated octahedrons to dispersive single octahedrons with increasing deposition current densities. The Cu2O- TNTs exhibited remarkable visible light responses with obvious visible light absorption and greatly enhanced visible light photoelectrochemical performance. The I-V characteristics under visible light irradiation show a distinct plateau in the region between approximately -0.3 and 0 V, resulting in higher open-circuit voltages and larger short-circuit currents with increased Cu2O deposition.     

Fe3+-TiO2/SiO2气相光催化降解乙醛反应动力学研究

用浸渍法制备了Fe^3 -TiO2／SiO2负载型光催化剂,并进行了光催化降解气相中乙醛的实验和动力学研究．结果表明,Fe^3 掺杂量(nFe3 ／nTi4)为0．5％时光催化降解乙醛的效率最高;水气的存在提高了Fe^3 -TiO2／SiO2负载型催化剂的光催化活性,但使Fe^3 -TiO2纳米粉的光催化活性降低;O2的存在使Fe^3 -TiO2纳米粉和Fe^3 -TiO2／SiO2负载型催化剂的催化活性均有所降低;光强减弱使乙醛降解率下降,反应速率与光强之间呈近似线性关系;光催化降解气相中乙醛的动力学可以用Langrauir-Hinshelwood动力学方程描述．     

Preparation, characterization and photocatalytic activity of N-doped TiO_2 nanocrystals

N-doped TiO_2 nanocrystals were prepared using titanium alkoxide as precipitant with different proportional materials. The products were characterized by X-ray diffraction,scanning electron microscopy,transmission electron microscopy, and UV-vis diffuse reflectance spectra. It is confirmed experimentally that the photocatalytic activity of N-doped TiO_2 is much higher than that of Degussa P25, when used for the degradation of crystal violet.The degradation kinetics follows an apparent first-order reaction,which is consistent with a generally observed Langmuir-Hinshelwood mechanism. The doping of TiO_2 with nitrogen significantly increases the absorption in the region of visible light. The energy of the band gap of N-doped TiO_2 is 2.92 eV. The better performante of N-doped TiO_2 can be explained by the fact that it is also excited with longer-wavelength light.     

CdS quantum dots-sensitized TiO2 nanotube arrays for solar cells

CdS quantum dots(QDs) sensitized TiO2 nanotube arrays photoelectrodes were investigated for their photovoltaic performance of quantum dots-sensitized solar cells. The highly ordered TiO2 nanotube arrays(TNAs) were synthesized on Ti foils by anodic oxidation method. Then CdS quantum dots were deposited onto the TiO2 nanotube arrays by successive ionic layer absorption and reaction(SILAR) method to serve as the sensitizers. Cd(NO3)2 and Na2S were used as the precursor materials of Cd+ and S2- ions, respectively. It is found that the CdS QDs sensitizer may significantly increase the light response of TiO2 nanotube arrays. With increasing CdS QDs deposition cycles, the visible light response increases. Maximum photocurrent was obtained for the QDs that have an absorption peak at about 500 nm. Under AM 1.5 G illuminations(100 mW cm-2), a 4.85 mA/cm2 short circuit current density was achieved, and the maximium energy conversion efficiency of the as-prepared CdS QDs-sensitized TNAs solar cells was obtained as high as 0.81 % at five SILAR cycles.     

Fe_3O_4-TiO_2磁性光催化剂的制备与性能

采用化学共沉淀法制备磁性纳米Fe3O4作为磁载体,以溶胶-凝胶法制备了Fe3O4-TiO2磁性光催化剂,采用X射线衍射(XRD)、紫外-可见(UV-Vis)漫反射等手段对其进行表征。以亚甲基蓝水溶液为模拟污染物,测试了Fe3O4-TiO2磁性光催化剂的光催化性能,光照90min后,亚甲基蓝的脱色率可达到96.6%,相同条件下TiO2对亚甲基蓝的脱色率为93.6%。在外加磁场作用下,Fe3O4-TiO2磁性光催化剂的平均回收率为85.6%,TiO2离心分离平均回收率为62.7%,Fe3O4-TiO2磁性光催化剂在保证高催化活性的前提下实现了高效回收。     

Na_2O-SiO_2-ZrO_2-TiO_2系统玻璃耐碱机理的研究

本文采用了分光光度法、原子吸收光谱法及电子探针(EPMA)等手段,对Na_2O-SiO_2-ZrO_2-TiO_2系统玻璃进行了耐碱机理的初步探讨。用相关分析对碱蚀液中ZrO_2、TiO_2、SiO_2等氧化物的碱溶出行为及各氧化物在玻纤表面上的残留行为进行了讨论。     

SO_4~(2-)-TiO_2/γ-Al_2O_3固体超强酸催化剂上的缩醛(酮)反应

通过浸渍法制备了SO42--TiO2/γ-Al2O3新型固体超强酸催化剂,以苯甲醛和乙二醇为原料合成了苯甲醛乙二醇缩醛。考察了催化剂的焙烧温度、带水剂的种类和体积、TiO2的质量分数、苯甲醛与乙二醇的摩尔比、催化剂的质量和回流时间对反应的影响以及催化剂稳定性对反应的影响。结果表明,在焙烧温度为500℃,甲苯为带水剂,甲苯体积为20 mL,TiO2的质量分数为10%,苯甲醛与乙二醇的摩尔比为1∶1.2,催化剂的质量为1.1 g,回流时间为1.5 h的反应条件下,苯甲醛乙二醇缩醛的收率可达96.1%,产品的纯度为99.6%。SO42--TiO2/γ-Al2O3新型固体超强酸催化剂在其它缩醛(酮)的合成中也具有良好的催化活性。     

X-RAY FLUORESCENCE SPECTRA ANALYSIS ON THE STRUCTURE AROUND Ti4+ OF BaO-SiO2-B2O3-TiO2 SYSTEM GLASSES

The structure around Ti~(4 ) in BaO-SiO_2-B_2O_3-TiO_2 had been studied by X-ray fluorescence spectra. The results show that the Ti~(4 ) mainly exists in the [TiO_4] and enters the network of [SiO_4]. [TiO_4] has the tendency to change to [TiO_6] with the increase of TiO_2 content. When the TiO_2 content increases to about 20mol% the tendency reaches its maximum.     

Cr沉积TiO_2复合薄膜的制备及其可见光催化性能

真空蒸镀法结合溶胶凝胶法成功制备Cr沉积TiO2三层复合薄膜.通过XRD、SEM、UV-vis等手段表征沉积Cr后的TiO2薄膜的结构、可见光吸收性能,以亚甲基蓝溶液为目标物评定其可见光光催化活性.结果表明:该法制备的Cr沉积TiO2复合薄膜,在723 K热处理后,蒸镀的金属层仍然为金属Cr,823 K时被氧化为Cr2O3.不同温度热处理后Cr沉积的TiO2复合薄膜在可见光区均表现出良好的光吸收性.而且随着热处理温度的升高,光吸收性能明显增强.降解实验表明,823 K热处理后的薄膜样品光催化性能最好.在可见光光照射2 h后,对亚甲基蓝溶液降解率接近40%.     

Highly Efficient Synthesis of Environmentally Friendly Ag-modified TiO_2 Nanoflowers to Enhance Photocatalytic Performance

Ag-modified TiO_2 nanoflowers were prepared using a two-step process. The experimental process is green and free from contamination and can be synthesized directly at room temperature. Compared with pure TiO_2, Ag-modified TiO_2 enhances the absorption of visible light and effectively promotes the detachment of photoelectron pairs, Ag-TiO_2 has a significantly enhanced visible light response activity to photodecomposition of methyl orange(MO). It is shown that the strong interaction between Ag nanoparticles and TiO_2 enhances the photocatalytic activity of TiO_2 nanoflowers. The self-made open-air reactor was used to test the photocatalytic performance of different samples. The results showed that Ag-modified TiO_2 nanoflowers had excellent photodegradation ability. After repeated photodegradation of MO, Ag-modified TiO_2 nanoflowers showed good stability.     

掺杂金属卟啉的TiO_2薄膜对活性艳红X-3B染料的光催化降解性能

采用溶胶凝胶的方法,将具有高光敏性的四(对羟基)苯基锌卟啉(ZnTHPP,下简称锌卟啉)在钛酸丁酯[Ti(OBu)4]水解的条件下均匀嵌入到了TiO2无机网络中,又采用旋涂法制备了ZnTHPP/TiO2复合薄膜。利用UV Vis吸收光谱对薄膜的紫外可见光吸收性质进行了研究,结果表明锌卟啉的加入能有效的拓宽TiO2的可见光吸收范围。通过光催化降解活性艳红X 3B染料实验,对所制备的ZnTHPP/TiO2复合薄膜的光催化活性进行了考察,研究发现以ZnTHPP/TiO2作为光催化剂对活性艳红X 3B染料能有效的降解,表现出了较好的可见光催化活性。     

Photogenerated carrier transfer mechanism and photocatalysis properties of TiO2 sensitized by Zn（ Ⅱ ） phthalocyanine

The Zn(Ⅱ) phthalocyanine sensitized TiO2(ZnPc-TiO2) nanoparticles were prepared by hydrothermal method via impregnation with ZnPc.The as-prepared photocatalysts were characterized by X-ray diffractometry(XRD) and diffuse reflectance spectroscopy(DRS),and the surface photovoltage spectroscopy(SPS) and photocatalytic degradation of rhodamine B(RhB) were studied under illuminating.The experimental results indicate that TiO2 sensitized by ZnPc extends its absorption band into the visible region effectively,and ...     

Enhanced Photoelectric Property of Mo-C Codoped TiO_2 Films Deposited by RF Magnetron Cosputtering

Mo-C codoped TiO_2 films were prepared by RF magnetron cosputtering. Ultraviolet-visible spectroscopy, atomic force microscopy, X-ray photoelectron spectroscopy, energy dispersive X-ray Analysis and X-Ray Diffraction were used to study the influences of codoping on energy gap, surface morphology, valence states of elements, ions content and crystal structure, respectively. The concentration of photogenerated carriers was measured by studying photocurrent density, while catalytic property was evaluated by observing degradation rate of methylene blue under visible light. A Mo-doped TiO_2 film, whose content of Mo had been optimized in advance, was prepared and later used for subsequent comparisons with codoped samples. The result indicates that Mo-C codoping could curtail the energy gap and shift the absorption edge toward visible range. Under the illumination of visible light, codoped TiO_2 films give rise to stronger photocurrent due to smaller band gaps. It is also found that Mo, C codoping results in a porous surface, whose area declines gradually with increasing carbon content. Carbon and Molybdenum doses were delicately optimized. Under the illumination of visible light, sample doped with 9.78at% carbon and 0.36at% Mo presents the strongest photocurrent which is about 8 times larger than undoped TiO_2 films, and about 6 times larger than samples doped with Mo only.     

金属酞菁敏化二氧化钛可见光催化降解染料废水的研究

研究了染料敏化半导体光催化剂-酞菁镁/TiO_2复合粒子在可见光波段的光催化性能.通过溶胶-凝胶的方法制得TiO_2胶体再进行焙烧,得到二氧化钛粉末和薄膜,再用酞菁镁敏化,制得酞菁镁/TiO_2复合粒子.利用X射线衍射、扫描电子显微镜、红外光谱和X光电子能谱分析等方法对TiO_2和酞菁镁/TiO_2复合粒子的物理性质进行了表征;并以亚甲基蓝作为目标物研究其光催化性能.结果表明,酞菁镁可以敏化二氧化钛,使其吸收波长红移,并具有较好的光催化性能.     

Cr2O3在一维TiO2中的掺杂行为

以硝酸铬和四氯化钛为前驱体,采用化学共沉淀法制得TiO2和Cr2O3的复合粉体。将复合粉体进行水热处理,用透射电子显微镜、场发射扫描电子显微镜、电子衍射、X射线衍射以及紫外-可见光谱吸收仪等测试手段对样品的形貌和成份以及光吸收性进行了分析。结果表明,水热处理后得到一维管状结构,其管长500~600 nm,直径10~20nm,壁厚4~6 nm。研究还发现,与纯的TiO2相比,Cr2O3/TiO2复合粉体的紫外-可见光吸收光谱显著红移。     

Ag_3PO_4光催化剂的合成和其光催化性能

用简单化学沉淀法制备了Ag3PO4可见光光催化剂,通过XRD、SEM和UV-Vis对其进行表征,并以若丹明B溶液为目标降解物研究了其光催化性能。UV-Vis图证实Ag3PO4对波长小于525nm范围内有明显吸收,可利用太阳光中的可见光。对比在可见光下光降解45min时的催化性能,N-TiO2催化降解率为8.1%,而Ag3PO4催化降解率为93.9%,表明Ag3PO4具有高效性;重复光催化5次Ag3PO4催化性能基本保持不变,催化降解率依次为93.9%、95.4%、95.5%、95.9%和96.5%,SEM图和XRD图显示,立方晶系的Ag3PO4在重复光催化5次后形貌和晶型均没有发生变化,以上实验结果表明其具有稳定性。因此,Ag3PO4是一种具有高效性和稳定性的可见光催化剂。     

机械化学法N掺杂纳米TiO2的制备与表征

采用机械化学法合成了N掺杂纳米TiO_2粉末,对所获得的N掺杂TiO_2粉末进行了分析与表征．实验结果表明,采用六次甲基四胺(HMT)为N源,将原料TiO_2和HMT混合物经过高能球磨处理后,合成的N掺杂TiO_2主要为锐钛矿和板钛矿的混晶相,与原料相比具有小的晶粒度和大的比表面积,对波长大于400nm的可见光具有良好的吸收性能,其吸收边红移至530nm．     

Enhanced photocatalytic degradation of methyl orange by CdS quantum dots sensitized platelike WO_3 photoelectrodes

CdS quantum dots sensitized platelike WO_3 photoelectrodes were successfully synthesized by a facile hydrothermal method and a modified chemical bath deposition(CBD) technique.To further improve the stability of the photoelectrodes in alkaline environment,the platelike WO_3 films were treated with TiCl_4 to form a nano-TiO_2 buffer layer on the WO_3 plate surface before loading CdSQDs.The resulting electrodes were characterized by using XRD,SEM,HR-TEM and UV-vis spectrum.The photocatalytic activity of the resulting electrodes was investigated by degradation of methyl orange(MO) in aqueous solution.The photoelectrochemical(PEC) property of the resulting electrodes was also characterized by the linear sweep voltammetry.The results of both the degradation of MO and photocurrent tests indicated that the as-prepared CdSQDs sensitized WO_3 platelike photoelectrodes exhibit a significant improvement in photocatalytic degradation and PEC activity under visible light irradiation,compared with unsupported CdSQDs electrodes.Significantly,coating the WO_3 plates with nano-TiO_2 obviously facilitate the charge separation and retards the charge-pair recombination,and results in a highest activity for QDsCdS/TiO_2/WO_3 photoelectrodes.     

A Fundamental DFT Study of Anatase(TiO_2) Doped with 3d Transition Metals for High Photocatalytic Activities

Anatase(TiO_2) has been widely used in photocatalysis. However, it can only absorb near-ultraviolet light with a wavelength below approximately 388 nm due to a wide band gap. Therefore a modification should be made for anatase to increase its capability in utilizing more abundant visible light. We investigated the doped anatase with the most promising 3d transition metal elements, and the results showed that the visible light absorption intensity was increased significantly due to the reduced band gap and the cavitation effects. As compared to other 3d transition metals, Cu was found to be the most effective one in improving anatase photocatalytic effects. In addition, greater Cu concentration doped in the anatase increased the photocatalysis effects but reduced the anatase stability, therefore, an optimized Cu concentration should be considered to optimize the anatase photocatalysis activity.