TiO_2分级结构/Ag_3PO_4复合材料的可见光催化性能

制备了具有分级结构的海胆状TiO2纳米材料,并通过原位沉积法将可见光响应的Ag3PO4纳米颗粒沉积到TiO2的纳米分级结构上,合成了具有高效稳定可见光催化性能的系列TiO2分级结构/Ag3PO4复合材料,对比测试了系列材料对罗丹明B(RhB)的光催化降解性能.结果表明,TiO2分级结构/Ag3PO4复合材料光催化性能明显高于纯相的Ag3PO4光催化剂,同时也明显优于TiO2(P25)/Ag3PO4复合光催化剂,其中分级结构TiO2与Ag3PO4摩尔比为1∶1的复合材料具有最强的光催化性能,在可见光照射6min内可实现RhB的完全脱色.分析结果表明,与纳米颗粒TiO2相比,具有海胆状纳米结构的TiO2可为Ag3PO4的负载提供更多的担载位点,增加TiO2和Ag3PO4的接触面积,进而提升Ag3PO4光激发产生的光生电子-空穴的分离效率.同时在光降解过程中,Ag3PO4表面存在的少量Ag+会逐渐还原成单质Ag0,通过Ag0的等离子体共振效应,可增加对光子的吸收转换能力,从而进一步提高该复合材料光催化降解染料的性能.     

碳纳米管/TiO_2复合材料的制备及表征研究

采用溶胶-凝胶法和水热合成法,制备出碳纳米管/TiO2(CNTs/TiO2)复合材料。通过X-射线衍射仪(XRD)、扫描电子显微镜(SEM),紫外-可见漫反射光谱(UV-Vis),荧光光谱(LS)检测CNTs/TiO2的晶型及形貌。结果表明:锐钛矿相TiO2纳米颗粒负载在碳纳米管的管壁上,CNTs/TiO2在紫外-可见光波长范围均有较好的吸收性能。在灭菌灯照射下,以甲基橙溶液为降解目标,CNTs/TiO2复合材料对甲基橙溶液的降解有高的光催化活性,180 min内降解率达到85%以上。     

溶剂热法制备Ag/TiO_2纳米材料及其光催化性能

以乙醇为溶剂,钛酸四丁酯为前驱体,用溶剂热法制备了Ag表面修饰的负载型纳米二氧化钛光催化剂.利用X射线衍射(XRD)、N2吸附-脱附(BET)、透射电子显微镜(TEM)、X射线光电子能谱(XPS)、紫外-可见(UV-Vis)光谱等技术对其进行了系统的表征,以亚甲基蓝(MB)溶液的脱色降解为模型反应,考察了不同Ag含量样品的光催化性能.结果表明:用溶剂热法制备的样品中TiO2皆为锐钛矿相,金属Ag颗粒沉积在TiO2表面,粒径为2nm左右,比表面积较溶胶凝胶法制备的样品大大增加,最高可达151.44m2·g-1;UV-Vis光谱和光催化实验表明:Ag修饰使TiO2对光的吸收能力大大增强,吸收带边红移至可见光区,亚甲基蓝在该复合材料上的光催化降解反应遵循一级反应动力学模型;溶剂热法制备样品的光催化性能明显好于溶胶凝胶法制备的样品,在紫外光和可见光下,Ag摩尔分数为5%的样品表现出最佳的光催化活性.     

Bi2O3 /TiO2复合纳米颗粒的可见光光催化性能

采用溶胶与水热相结合的方法合成了具有可见光光催化活性的复合纳米颗粒Bi2O3/TiO2,并对其进行了X射线衍射、透射电镜、X射线光电子能谱、紫外-可见漫反射谱、红外光谱、低温N2吸附脱附及电子顺磁共振分析。结果表明,复合少量的氧化铋可显著抑制TiO2由锐钛矿到金红石的相转移过程,并将光吸收范围扩展到可见光区。可见光照射下(λ>420 nm),利用电子顺磁共振技术检测到明显的羟基自由基(.OH)信号。铋的最佳掺杂量为Bi/Ti质量比2.0%,适量铋的掺入能显著改善锐钛矿TiO2的结晶度,抑制光生电子-空穴对的复合,提高光催化量子效率。通过可见光照射下,4-氯酚的降解实验测试Bi2O3/TiO2复合纳米颗粒的可见光光催化活性。同时,利用气-质联用仪对4-氯酚降解过程的中间产物进行了测定,并提出可见光照射下的Bi2O3光敏化机理。     

Ag负载TiO2纳米管微波辅助水热法制备及其光催化性能

以微波辅助水热法制备了二氧化钛纳米管,然后通过浸渍法在其表面负载了银纳米颗粒.所得样品用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、氮吸附、X射线光电子能谱(XPS)、紫外-可见漫反射等测试方法表征.微波加热处理可以大大缩短反应时间,产物为无定型纳米管,经高温焙烧后转变成锐钛矿型二氧化钛.所得纳米管的外径为7-8 nm,内径为5-6 nm,管长约200 nm,比表面积可达371 m2·g-1.负载的银分散在纳米管的表面,对纳米管的结构与晶型没有影响,但是拓宽了二氧化钛的光吸收范围,使吸收边红移至可见光区,并且有效抑制了光生电子空穴的复合.在可见光降解罗丹明B的实验过程中,与Ag负载的P25及纯二氧化钛纳米管相比,Ag负载二氧化钛纳米管具有更高的可见光催化活性,并且当Ag/Ti 物质的量的比为0.5%时,可见光催化性能最好.     

Ag@AgCl修饰的锐钛矿相TiO2纳米管的制备及其光催化性能

首先采用水热合成法和双氧水处理制备了具有锐钛矿相的TiO2纳米管,然后通过沉淀和光化学反应将Ag@AgCl纳米粒子负载于其上,从而制得TiO2纳米管负载的表面等离子体光催化剂.结果表明,经Ag@AgCl纳米粒子修饰后,锐钛矿相TiO2纳米管因表面等离子共振效应而对可见光具有明显的响应,光生电子-空穴对更容易分离,因而T...     

N掺杂纳米TiO2可见光催化氧化丙烯的动力学行为

通过在不同温度的氨气气氛中处理纳米管钛酸(NTA)制得具有可见光响应的氮掺杂纳米二氧化钛. X射线衍射(XRD)谱表征结果显示, 当温度高于400 ℃时, 样品由正交晶系向锐钛矿相转变, 700 ℃处理得到的样品除了锐钛矿相TiO2外还有TiN 新相存在; 紫外-可见扩散漫反射(DRS)结果表明, 氮掺杂纳米TiO2在整个可见光区都有明显的吸收. 不同波长可见光及不同气体流速的光催化氧化丙烯动力学研究表明, 活性最好的N掺杂纳米TiO2催化剂(600 ℃ NH3处理)对可见光的利用范围可扩展至500 nm, 低浓度丙烯光催化氧化反应为一级反应.     

掺铁纳米TiO_2的制备及其光催化性能

以TiC l4为原料,采用微波加热与常规加热2步合成法制备掺铁纳米TiO2。用X射线粉末衍射(XRD)、透射电镜(TEM)、紫外可见吸收光谱(UV-V is)、光电子能谱(XPS)等测试技术对其进行了表征。结果表明,所制得的掺铁纳米TiO2是以锐钛矿为主相的混晶,平均粒径约为10 nm,适量Fe3+的掺杂能促进金红石相变,抑制锐钛矿晶粒的生长,使Ti2p电子结合能升高0.3 eV,并使TiO2吸光能力增强,带边吸收向可见光区移动。在UVA段(320~400 nm)光照下,通过对维生素VB12的光催化降解,发现掺入摩尔分数为0.5%的Fe3+的纳米TiO2能明显提高其光催化活性,使维生素B12的降解速率提高2.3倍。     

尿素为氮源N-TiO2的制备、表征及光催化性能

以钛酸丁酯为前驱体,以尿素为氮源,采用溶胶-凝胶法制备了不同N含量的TiO2光催化剂(N-TiO2).通过X-射线衍射(XRD)、紫外-可见吸收光谱(UV-Vis)、分子荧光光谱(PL)、X-射线光电子能谱(XPS)等检测手段对其结构和物理性能进行了表征.结果表明,N的掺杂能抑制锐钛矿相TiO2向金红石相的转化,能将TiO2的吸收边波长拓宽到可见光区域,能加速光生电子-空穴对的分离,提高光催化活性.在以可见光为光源进行重铬酸钾的光催化还原和苯酚的光催化氧化反应中,9%N-TiO2-500表现出了最强的光催化活性,且在光催化活性的稳定性实验中,表现出良好的光催化活性的稳定性,能多次重复使用.     

g-C3N4/Ag/TiO2复合材料的构筑及其光催化性能（英文）

以合成的g-C3N4纳米片和Ag/TiO2空心微球为原料,采用机械搅拌的方法构筑了g-C3N4/Ag/TiO2三元复合光催化剂。采用X射线衍射(XRD)、傅里叶变换红外光谱(FT-IR)、扫描电镜(SEM)、X射线光电子能谱(XPS)、紫外-可见光漫反射(UV-Vis DRS)和光致发光光谱(PL)对g-C3N4/Ag/TiO2进行了表征。研究表明,g-C3N4/Ag/TiO2是由Ag/TiO2微球和g-C3N4纳米片复合而成的。与TiO2相比,其可见光响应范围延长,光生载流子的分离速率加快。在室温下,用降解罗丹明B的反应考察了g-C3N4/Ag/TiO2的可见光催化活性。研究表明,光照180 min时,g-C3N4(0.5%)/Ag/TiO2显示了最高的光催化活性(91.9%),分别是TiO2和Ag/TiO2的7.5和1.8倍。光催化活性的提高与合理的异质结构建和Ag的导电性能有关。     

In situ photoexcitation of silver-doped titania nanopowders for activity against bacteria and yeasts

Photocatalytic and in situ microbial activity of the amorphous and annealed states of Ag-doped and un-doped titania were examined. Studies on their structure, morphology, composition, and the photo-absorption characteristics of these materials were performed. These results were correlated with the photocatalytic and microbial activity against methicillin resistant Staphylococcus aureus K324 (MRSA), methicillin susceptible S. aureus ATCC 25923 (MSSA), Escherichia coli PA 170, and yeasts Candida albicans ATCC 90028. The annealed powders containing anatase form of titania exhibited relatively higher photocatalytic activity,corresponding to activity against MRSA,when exposed to UV-A radiation. In comparison, amorphous powders exhibited low photoactivity and showed poor antibacterial performance against MRSA under UV-A exposure. Doping of amorphous titania with Ag resulted in an anti-MRSA effect without exposure to UV radiation. In the Ag-doped crystalline anatase samples, the size of Ag primary nanocrystallites increased, which led to the decrease in the surface concentration of Ag and detriment anti-MRSA activity.     

Precise Size Control over Ultrafine Rutile Titania Nanocrystallites in Hierarchical Nanotubular Silica/Titania Hybrids with Efficient Photocatalytic Activity

Hierarchical‐structured nanotubular silica/titania hybrids incorporated with particle‐size‐controllable ultrafine rutile titania nanocrystallites were realized by deposition of ultrathin titania sandwiched silica gel films onto each nanofiber of natural cellulose substances (e.g., common commercial filter paper) and subsequent flame burning in air. The rapid flame burning transforms the initially amorphous titania into rutile phase titania, and the silica gel films suppress the crystallite growth of rutile titania, thereby achieving nano‐precise size regulation of ultrafine rutile titania nanocrystallites densely embedded in the silica films of the nanotubes. The average diameters of these nanocrystallites are adjustable in a range of approximately 3.3–16.0 nm by a crystallite size increment rate of about 2.4 nm per titania deposition cycle. The silica films transfer the electrons activated by crystalline titania and generate catalytic reactive species at the outer surface. The size‐tuned ultrafine rutile titania nanocrystallites distributed in the unique hierarchical networks significantly improve the photocatalytic performance of the rutile phase titania, thereby enabling a highly efficient photocatalytic degradation of the methylene blue dye under ultraviolet light irradiation, which is even superior to the pure anatase‐titania‐based materials. The facile stepwise size control of the rutile titania crystallites described here opens an effective pathway for the design and preparation of fine‐nanostructured rutile phase titania materials to explore potential applications.     

Visible light photocatalyst: iodine-doped mesoporous titania with a bicrystalline framework

Iodine-doped (I-doped) mesoporous titania with a bicrystalline (anatase and rutile) framework was synthesized by a two-step template hydrothermal synthesis route. I-doped titania with anatase structure was also synthesized without the use of a block copolymer as a template. The resultant titania samples were characterized by X-ray diffraction, Raman spectroscopy, Fourier transform infrared, nitrogen adsorption, transmission electron microscopy, X-ray photoelectron spectroscopy, and UV-visible absorption spectroscopy. Both I-doped titania samples, with and without template, show much better photocatalytic activity than commercial P25 titania in the photodegradation of methylene blue under the irradiation of visible light (>420 nm) and UV-visible light. Furthermore, I-doped mesoporous titania with a bicrystalline framework exhibits better activity than I-doped titania with anatase structure. The effect of rutile phase in titania on the adsorptive capacity of water and surface hydroxyl, and photocatalytic activity was investigated in detail. The excellent performance of I-doped mesoporous titania under both visible light and UV-visible light can be attributed to the combined effects of bicrystalline framework, high crystallinity, large surface area, mesoporous structure, and high visible light absorption induced by I-doping.     

微乳法合成纳米SiO2/TiO2及其光催化性能

采用聚乙二醇辛基苯基醚(Triton X-100)/正己醇/环己烷/氨水微乳体系合成了纳米TiO2和SiO2/TiO2复合物,用X射线衍射、红外光谱和透射电镜对其结构进行了表征,并以甲基橙降解评价了其光催化性能,讨论了SiO2/TiO2摩尔比、晶相组成及粒径与光催化活性的关系.结果表明,SiO2/TiO2催化剂中形成了新的Ti-O-Si键和无定形SiO2;在纳米TiO2中复合SiO2能有效抑制锐钛矿向金红石的转变,增加锐钛矿的稳定性,并阻止TiO2晶粒的聚集生长.催化剂的光催化活性随金红石含量的增加而降低,加入适量SiO2能明显提高TiO2的光催化活性,其中摩尔比为1/7的SiO2/TiO2光催化活性最高.     

TiO2纳米晶光催化降解铬酸根离子的研究

以二氧化钛为光催化剂,研究了溶液的ｐＨ值、铬酸根离子的初始浓度、通入的气体种类、氧化钛的载量等因素对铬酸根离子降解率的影响。同时合成了粒径小于１０ｎｍ的锐钛矿相和金红石相氧化钛纳米晶来考察晶相和尺寸效应对降解率的影响。结果表明,锐钛矿的催化活性高于金红石相,两者的催化活性均大大高于市售的氧化钛微粉。     

Large-scale preparation of ordered titania nanorods with enhanced photocatalytic activity

A titania layer with ordered nanostructures is expected to be of high photocatalytic activity due mainly to its high specific surface area. In the present work, large-area films with ordered titania nanorods were deposited on titanium substrates through a solution approach. The nanorods, with the phase composition of a mixture of anatase and rutile, grew on top of a condensed anatase interlayer along mainly the rutile [001]-axis. The photocatalytic activity was evaluated by decomposing rhodamine B in water and compared with the general sol-gel derived titania films and a commercial DP-25 titania coating. It is found that the as-deposited titania nanorods exhibited extremely high initial photocatalytic activity but declined to a poor value after the consumption of beneficial oxidative peroxo complexes coordinated to Ti(IV). A subsequent thermal treatment eliminated such complexes but at the same time improved the crystallinity of the titania nanorods. The photocatalytic activity of the thermally treated titania nanorods was stable and significantly higher than that of the sol-gel derived film and commercial DP-25 coating.     

Titania nanotubes (TNTs) prepared through the complex compound of gallic acid with titanium; examining photocatalytic degradation of the obtained TNTs

It was for the first time that the complex compound of gallic acid with titanium (IV) salt was used as a precursor to synthesize titania nanotubes. The study was separated into four main sections; (I) synthesizing the complex of titanium with gallic acid, (II) synthesizing anatase and rutile phases through thermal decomposing of the complex, (III) investigating the possibility to synthesize titania nanotubes from the rutile and anatase phases, and (IV) photocatalytic ability of all the nanoparticles.Different methods were applied to analysis, including X-ray diffraction, 1H NMR, FT-IR spectroscopy, elemental analysis, quantum-chemical modeling, Raman spectroscopy, thermal analysis, photoluminescence, BET analysis (to investigate the specific surface activity, total pore volume), EDX, electron microscopy (SEM), acceleration voltages, electrical conductivity, BJH method (to determine average pore diameter), and UV-Vis spectroscopy.We illustrated the possibility of the synthesis of the titania nanotubes from the anatase phase, while rutile phase was not turned to a tube shape.The photocatalytic ability of the obtained nanoparticles was tested by degrading bromophenol blue, as an organic pollutant, under weak light. TiO₂ in the form of nanotubes could reduce the concentration of bromophenol blue to 82%, as well as the rutile phase - to 70%, and finally anatase as nan-spheres to 36%.     

Preparation of nano and microcrystals of silver using titania xerogel matrix as template

Ag-doped TiO₂ wet gels were prepared by sol?Cgel process using a mixture of titanium isopropoxide and silver nitrate as precursor solution, with Ag:Ti molar ratio of 1:6. After drying, the titanium oxide xerogels were used as template in the preparation of nano and microcrystals of metallic silver. The porous network and the structure of the titania matrix influenced the type and distribution of silver crystal produced on the composite surface. Silver nanoparticles segregated to the surface of titania xerogel during the heating step, giving rise to nanocrystals that coalesced forming microcrystals with different shapes and faceting. The microcrystals grew on the composite surface, reaching sizes between 5 and 20 microns and self-organized of different ways. The xerogel heated at 600 °C formed by anatase, rutile and silver nanoparticles exhibited considerable photocatalytic activity to degrade methylene blue.     

Hierarchical‐Structured Anatase‐Titania/Cellulose Composite Sheet with High Photocatalytic Performance and Antibacterial Activity

Bulk hierarchical anatase‐titania/cellulose composite sheets were fabricated by subjecting an ultrathin titania gel film pre‐deposited filter paper to a solvo‐co‐hydrothermal treatment by using titanium butoxide as the precursor to grow anatase‐titania nanocrystallites on the cellulose nanofiber surfaces. The titanium butoxide specie is firstly absorbed onto the nanofibers of the cellulose substance through a solvothermal process, which was thereafter hydrolyzed and crystallized upon the subsequent hydrothermal treatment, leading to the formation of fine anatase‐titania nanoparticles with sizes of 2–5 nm uniformly anchored on the cellulose nanofibers. The resulting anatase‐titania/cellulose composite sheet shows a significant photocatalytic performance towards degradation of a methylene blue dye, and introduction of silver nanoparticles into the composite sheet yields an Ag‐NP/anatase‐titania/cellulose composite material possessing excellent antibacterial activity against both Gram‐positive and Gram‐negative bacteria.     

微乳法制备纳米TiO2 /SiO2的结构及光催化研究

Nanosized TiO₂ and TiO₂/SiO₂ particles were prepared by hydrolysis of tetrabutyl titanate (TBOT) and tetraethyl orthosilicate (TEOS) in the TX-100 reverse microemulsion. These particles were characterized by TG-DSC, XRD, FTIR, TEM，N₂ adsorption-desorption. Their photocatalytic activity was tested by degradation of methyl orange. The result shows that TiO₂/SiO₂ nanoparticles are with a monodispersed spherical phase and a uniform size distribution，and TiO₂ particles are dispersed on the surface of SiO₂. The band for Ti-O-Si vibration in FTIR was observed, the Ti-O-Si bond increased the stability of anatase TiO₂, suppressed the phase transformation of titania from anatase to rutile. And due to the addition of SiO₂, the average size of titania decreased from 38 nm in pure TiO₂ to 5 nm in TiO₂/SiO₂. It was found, under UV light irradiation, TiO₂/SiO₂ particles showed higher activity than pure TiO₂, and TiO₂/SiO₂(1/1) particles showed the highest photocatalytic activity on the photocatalytic decomposition of methyl orange, which was influenced by crystal structure, particle size, crystallinity and Surface area Characteristics.