低温制备CdS/TiO_2纳米复合材料及其光催化性能研究

采用超声醇盐水解法在低温水浴条件下制备不同质量比的CdS/TiO2纳米复合材料。以甲基橙为目标污染物,考察了不同质量比的CdS/TiO2的光催化效果。采用X-射线衍射(XRD)、扫描电子显微镜(SEM)和傅里叶红外光谱(FT-IR)对所合成的纳米复合材料进行了结构和形貌的表征。结果表明:质量比1∶100的CdS/TiO2复合材料分散较均匀,TiO2以锐钛矿型存在,CdS以六方相存在。在模拟太阳光下降解甲基橙5h,降解率达到66.53%,在紫外光下降解5h,降解率达到97.00%。     

光催化原位氧化聚合法制备聚吡咯/TiO_2复合材料及其可见光催化降解罗丹明B的性能

在无需引发剂的条件下,通过光催化原位氧化聚合法一步合成了聚吡咯/TiO2纳米复合材料(PPy/TiO2)。采用UV-Vis、XRD、XPS和FTIR技术对吡咯在TiO2表面的聚合过程和复合材料的结构进行了表征。以罗丹明B(RhB)的降解反应研究了PPy/TiO2复合材料的光催化性能。研究表明,紫外光(λ=365nm)激发TiO2形成电子-空穴对,空穴迁移至表面与吸附于TiO2表面的吡咯单体作用,迅速形成吡咯阳离子和低聚体,最终形成聚吡咯并包覆在TiO2的表面。光催化结果表明,PPy/TiO2复合材料可加速RhB在可见光和紫外光下的降解速率,所制备的PPy/TiO2复合材料是一种可应用于光电转化和光催化方面的多功能材料。     

TiO_2纳米管/碳纳米管复合材料光催化降解玫瑰红染料废水的研究

主要介绍水热法制备TiO2纳米管/碳纳米管(TiO2/CNT)复合材料及其光催化降解染料废水的研究。结果表明,用水热法制备出的TiO2纳米管和CNT的掺杂比例为5∶1时,TiO2纳米管/碳纳米管(TiO2/CNT)复合材料光催化降解玫瑰红染料废水的效果最佳,而且TiO2纳米管/碳纳米管复合材料具有较好的稳定性。研究证实了TiO2纳米管/碳纳米管复合材料对玫瑰红染料废水在模拟太阳光照射下具有较好的光催化效果。     

可见光响应C掺杂纳米TiO2的研究进展

纳米TiO_2的禁带宽度(3.2 Ev)限制了对太阳光能的利用,对纳米TiO2进行掺C改性能减小带隙、显著提高对可见光的利用,同时保持紫外光光催化活性,显示出良好的应用前景.综述和分析了C掺杂纳米TiO2的可见光活性理论、制备方法、在环境污染治理等方面的应用,及C和其它元素共掺杂改性TiO2的研究.总结了C掺杂纳米TiO2研究中存在的问题,并讨论了今后的研究方向.     

聚苯胺改性纳米TiO_2的制备及其光催化性能

通过矿化接枝技术将溶胶-凝胶法制备的纳米TiO2负载在聚苯乙烯微珠裁体上,制成负载型纳米TiO2光催化剂.利用导电聚苯胺对负载型纳米TiO2光催化剂进行可见光改性,通过XRD、SEM等方法对改性纳米TiO2先催化剂进行表征,并用改性催化剂在太阳光照射下对3种工业含氰废水进行降解处理.结果表明,导电聚苯胺对负载型纳米TiO2光催化剂的涂膜改性,显著改善了负载型纳米TiO2光催化剂在可见光条件下的光催化性能,可有效降解废水中的大部分有毒氰根(CN-),使其含量远低于国家排放标准.     

PEO改性纳米TiO2/LDPE复合薄膜的光降解性能

以聚氧乙烯(PEO)改性纳米TiO2颗粒作为光催化剂,与低密度聚乙烯(LDPE)树脂复合制备了一种新型可光催化降解的TiO2/LDPE纳米复合薄膜,进行了该薄膜在空气中紫外光照下的光催化降解实验。通过表面接触角、失重率、红外光谱(FT-IR)和扫描电镜(SEM)等分析技术系统地研究了该复合薄膜的降解性能。结果表明,PEO的加入能提高薄膜的亲水性和TiO2的分散性,提高TiO2的光催化活性,有利于促进LDPE薄膜的降解。TiO2/PEO/LDPE复合薄膜在0.8mW/cm2紫外光强下照射425h,失重率达到15.2%;在4mW/cm2紫外光强下照射500h,失重率达到38.1%。光照后薄膜的拉伸强度和断裂伸长率显著降低,羰基指数升高。     

磁响应性TiO2/石墨烯纳米复合材料的合成及光催化性能

采用乳液插层水解法成功制备了一种层状磁响应性光催化纳米复合材料.首先通过水热法制备磁性Fe3O4纳米粒子,将其超声分散在溶有钛酸丁酯的无水乙醇中,形成钛酸丁酯包裹Fe3O4纳米粒子的微乳液,然后将该微乳液插层于石墨烯中,利用石墨烯的层状结构作为载体形成一种稳定体系,通过控制水解,使TiO2纳米粒子与磁性Fe3O4纳米粒子共同镶嵌于石墨烯层间,形成一种新型的磁响应TiO2/石墨烯纳米复合材料.通过扫描电镜(SEM)、透射电镜(TEM)、X射线衍射(XRD)、震动样品磁强计(VSM)等手段对该复合材料进行表征,并通过模拟太阳光下降解亚甲基蓝(MB)评价复合材料的光催化性能.该复合材料通过磁分离可反复使用,重复使用7次后,对亚甲基蓝的降解率仍大于90％.     

PPy/TiO2纳米复合材料的制备及光催化活性

采用原位聚合的方法合成了聚吡咯/二氧化钛(PPy/TiO2)纳米复合材料,研究了吡咯(Py)与TiO2的比例、氧化剂的种类、掺杂酸的浓度等因素对PPy/TiO2纳米复合材料在太阳光下光催化降解甲基橙的影响,采用透射电镜、紫外-可见漫反射吸收光谱等方法对样品进行了表征.结果表明,PPy/TiO2纳米复合粒子在太阳光下的光催化活性明显高于TiO2纳米粒子,当Py与TiO2的比例为1:100,三氯化铁为氧化剂,1.0mol·L-1盐酸溶液为掺杂剂时PPy/TiO2纳米复合粒子在太阳光下的光催化活性最高;TiO2纳米微粒以及PPy/TiO2纳米复合微粒的粒径均为10～20nm,复合微粒的粒径没有明显的增大,但是减轻了纳米粒子之间的团聚;聚吡咯使TiO2纳米粒子的禁带宽度由3.12eV降低到2.84eV,TiO2纳米粒子的吸收波长拓展到可见光区,有利于TiO2纳米粒子在太阳光下光催化活性的提高.     

石墨烯/Ni/TiO_2/CNTs复合物的制备及其光催化性能

首先通过溶剂热法,在石墨烯表面负载掺杂镍的纳米二氧化钛膜,制备石墨烯/Ni/TiO2复合材料;然后以掺杂的镍为催化剂,采用化学气相沉积法,原位生长碳纳米管(CNTs),得到石墨烯/Ni/TiO2/CNTs复合材料。通过XRD、SEM、TEM、拉曼等方法对制备样品的晶型、微观形貌等进行了表征,考察了样品在紫外光及可见光下对甲基橙的光催化降解性能。结果表明:石墨烯和CNTs的加入使得Ni/TiO2、石墨烯/Ni/TiO2、石墨烯/Ni/TiO2/CNTs复合物的光催化活性依次提高,并且石墨烯/Ni/TiO2/CNTs复合物中石墨烯含量越多时,所得复合物的光催化降解性能越好。石墨烯含量最大的石墨烯/Ni/TiO2/CNTs样品,在紫外光下对甲基橙的降解率达到98%,在可见光下的光催化降解效率比掺镍TiO2提高了3.5倍。     

CNT/TiO2复合材料的合成、表征及其光催化性能分析

采用多壁碳纳米管(MWCNTs)为原料,分别以异丙醇钛(TIP)、丙氧基钛(TPP)和四丁氧基钛(TNB)为钛源,苯作为溶刺,制备了CNT/TiO2复合材料.利刖N2吸附等温线,扫描电子显微镜(SEM),X-射线衍射(XRD),能量分散性X-射线分析(EDX)以及紫外吸收光谱对所制CNT/TiO2复合材料进行了表征.并在紫外光照射下,通过亚甲蓝(MB,C16H18N3S·Cl·3H2O)水溶液的转,变测试了CNT/TiO2复合材料的光催化性能.研究结果表明:CNT/TiO2复合材料对MB的降解作用不仅有MWCNT的吸附性和TiO2的光催化性,而且还有MWCNT和TiO2之间的电子转移性.     

New TiO2/MgAl-LDH nanocomposites for the photocatalytic degradation of dyes

In this study we report the synthesis of a series of composite nanostructures comprising LDH and TiO2 phases. The materials characterization showed that the LDH crystallites are encapsulated inside the TiO2 matrix after the anatase seeds are deposited on MgxAl-LDHs. The structure in which LDH phase is embedded into anatase matrix is unique bringing important advantages to the photocatalytic performances of the nanocomposites. The photocatalytic activity of the prepared nanocomposites was tested on the degradation of the methylene blue (MB) in aqueous solution. The photocatalytic activities of the nanocomposites were compared with commercial TiO2 nanoparticles Degussa P25. The nanocomposites exhibited superior photocatalytic activity in basic environment because the negatively charged surface of TiO2 nanoparticles at high pH attracts the positively charged methylene blue species.     

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.     

Characterization of silver nanoparticles synthesized on titanium dioxide fine particles

Silver nanoparticles with a narrow size distribution were synthesized over the surface of two different commercial TiO(2) particles using a simple aqueous reduction method. The reducing agent used was NaBH(4); different molar ratios TiO(2):Ag were also used. The nanocomposites thus prepared were characterized using transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), x-ray photoelectron spectroscopy (XPS), x-ray diffraction (XRD), dynamic light scattering (DLS) and UV-visible (UV-vis) absorption spectroscopy; the antibacterial activity was assessed using the standard microdilution method, determining the minimum inhibitory concentration (MIC) according to the National Committee for Clinical Laboratory Standards. From the microscopy studies (TEM and STEM) we observed that the silver nanoparticles are homogeneously distributed over the surface of TiO(2) particles and that the TiO(2):Ag molar ratio plays an important role. We used three different TiO(2)Ag molar ratios and the size of the silver nanoparticles is 10, 20 and 80?nm, respectively. It was found that the antibacterial activity of the nanocomposites increases considerably comparing with separated silver nanoparticles and TiO(2) particles.     

Synthesis of beta-cyclodextrin-modified water-dispersible Ag-TiO2 core-shell nanoparticles and their photocatalytic activity

The beta-cyclodextrin-modified Ag-TiO2 core-shell nanoparticles were prepared by sodium borohydrate reduction of AgNO3 and the subsequent hydrolysis of the tetraisopropyl orthotitanate in an aqueous medium. Inversely in the preparation of beta-cyclodextrin-modified TiO2-Ag core-shell nanoparticles, first hydrolysis and then following reduction were carried out. The synthesized spherical core-shell nanoparticles were highly water-dispersible and had an average diameter in the range of 9 to 12 nm. A significant shifting of surface plasmon band was observed for the synthesized Ag-TiO2 and TiO2-Ag core-shell nanoparticles. On a model reaction, namely, the photodegradation of phenol by the UV light irradiation, the photocatalytic property of TiO2 nanoparticles was enhanced, when the Ag nanoparticle was embedded in the core of TiO2 nanoparticles but TiO2 nanoparticles coated by Ag shell decreased the photocatalytic property of TiO2 nanoparticles. The mechanism is ascribed to the surface plasmon characteristics of Ag in the core of the TiO2 nanoparticles under the acceleration by host-guest inclusion characteristics.     

The effects of synthesis procedures on the morphology and photocatalytic activity of multi-walled carbon nanotubes/TiO(2) nanocomposites

This study investigates the microstructures of multi-walled carbon nanotubes (MWNTs)/TiO(2) nanocomposites, obtained by sol-gel and hydrothermal processes. The synthesized nanocomposite materials were characterized by x-ray diffractometry (XRD), Brunauer-Emmett-Teller (BET) adsorption analysis, transmittance electron microscopy (TEM), scanning electron microscopy (SEM), photoluminescence (PL) spectroscopy, and x-ray photoelectron spectroscopy (XPS). The effects of the synthetic procedures and MWNTs on the morphology and photocatalytic activity of the nanocomposites were studied. The photocatalytic activity of the MWNTs/TiO(2) nanocomposite was elucidated based on the photooxidation of NO(x) under UV light illumination. A fleck-like and well dispersed TiO(2) microstructure on the surface of the MWNTs was observed in the sol-gel system, while compact and large aggregated particles were found in the hydrothermal procedure. The nanocomposite prepared by the sol-gel system exhibits better photocatalytic activity for NO oxidation (from 20.52 to 32.14%) than that prepared by the hydrothermal method (from 22.58 to 26.51%) with the same MWNT loading (from 0 to 8?wt%), respectively. The optimal MWNT content in the nanocomposite was considered at 8?wt%. Additionally, results confirm that the introduction of MWNTs will cause the NO(2) to be more consumed than NO in the photocatalytic experiments, leading to more complete NO(x) photooxidation. These observations indicate that the different TiO(2) distributions on the MWNT surfaces and MWNT contents in the materials would determine the morphology, the physicochemical and photocatalytic characteristics for the nanocomposite materials.     

Improved photocatalytic activity of anisotropic rutile/anatase TiO2 nanoparticles synthesized by the Ti-peroxo complex method

Anisotropic rutile/anatase TiO2 nanoparticles (AB-TiO2) were synthesized by the Ti-peroxo complex method. Their photocatalytic activity in the degradation of Rhodamine B (RhB) was evaluated and compared to that of commercial TiO2 P25 and TiO2 obtained through the benzyl alcohol route (OB-TiO2). The samples were characterized by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR in DRIFT mode), Field-Emission Scanning Electronic Microscopy (FEG-SEM), N2 physisorption and UV-visible spectroscopy. Photodegradation of RhB was carried out under visible light and the results revealed a remarkable photocatalytic activity of the AB-TiO2 in terms of surface area. The excellent performance of the AB-TiO2 was explained in light of the synergistic effect of the coexistence of anatase/rutile phases, anisotropy and irreversible adsorption of organic species during sol-gel synthesis. UV-visible measurements also indicated that N-deethylation and photobleaching mechanisms occur to different extents, depending on the surface composition of the photocatalyst.     

Preparation and characterisation of TiO2 nanoparticle and titanate nanotube obtained from Ti-salt flocculated sludge with drinking water and seawater

This study aimed to prepare and characterise titanium dioxide (TiO2) nanoparticles and titanate nanotubes produced from Ti-sat flocculated sludge with drinking water (DW) and seawater (SW). The Ti-salt flocculated sludge from DW and SW was incinerated at 600 degrees C to produce TiO2 nanoparticles. XRD results showed that the anatase TiO2 structure was predominant for TiO2 from DW (TiO2-DW) and TiO2 from SW (TiO2-SW), which were mainly doped with carbon atoms. Titanate nanotubes (tiNT) were obtained when TiO2-DW and TiO2-SW were hydrothermally treated with NaOH solution. Structure phase, shape, crystallisation and photocatalytic activity of tiNT were affected by the incineration temperature and the amount of sodium present in different tiNT. The tiNT doped with thiourea incinerated at 600 degrees C presented anatase phase, showing a high increase of the degree of crystallisation with nanotube-like structures. The photocatalytic activity of these photocatalysts was evaluated using photooxidation of gaseous acetaldehyde. Thiourea doped tiNT-DW and tiNT-SW showed similar photocatalytic activity compared to commercially available TiO2-P25 under UV light and indicated a photocatalytic activity under visible light.     

Effect of surface plasmon resonance on the photocatalytic activity of Au/TiO2 under UV/visible illumination

In this study, gold-loaded titanium dioxide was prepared by an impregnation method to investigate the effect of surface plasmon resonance (SPR) on photoactivity. The deposited gold nanoparticles (NPs) absorb visible light because of SPR. The effects of both the gold content and the TiO2 size of Au/TiO2 on SPR and the photocatalytic efficiency were investigated. The morphology, crystal structure, light absorption, emission from the recombination of a photoexcited electron and hole, and the degree of aggregation were investigated using transmission electron microscopy (TEM), X-ray diffraction (XRD), UV-visible-diffuse reflectance spectra (UV-VIS-DRS), photoluminescence (PL) spectroscopy, and turbidimetry, respectively. Photocatalytic activity was evaluated by the decolorization of methyl orange solution over modified titania under UV and UV/GLED (green light emitting diode) illumination. Au/TiO2 NPs exhibited an absorption peak (530-570 nm) because of SPR. The results of our photocatalytic experiments indicated that the UV-inducedly photocatalytic reaction rate was improved by simultaneously using UV and green light illumination; this corresponds to the adsorption region of SPR. Au/TiO2 could use the enhanced electric field amplitude on the surface of the Au particle in the spectral vicinity of its plasmon resonance and thus improve the photoactivity. Experimental results show that the synergistic effect between UV and green light for the improvement of photoactivity increases with increasing the SPR absorption, which in turn is affected by the Au content and TiO2 size.     

ZnS在TiO2纳米管上的分散对其光催化降解染料废水的影响

水热法制备了TiO2纳米管,并采用简单加热回流的方法制备了ZnS/TiO2纳米复合材料。采用TEM、XRD分析手段对产物进行表征,并对其光催化降解酸性玫瑰红B(AR)染料废水进行了研究。考察了反应物供给速率、硫化锌复合量、催化剂稳定性、光照对光催化降解效果的影响。研究表明控制反应物供给速率和硫化锌的负载量可使硫化锌在二氧化钛纳米管表面均匀分散。当染料废水初始浓度为10mg/L,ZnS:TiO2=8:1时,ZnS/TiO2复合材料光催化活性最高。且催化剂稳定性较好。     

Synthesis and photo-degradation application of WO3/TiO2 hollow spheres

A WO(3)/TiO(2) composite, hollow-sphere photocatalyst with average diameter of 320 nm and shell thickness of 50 nm was successfully prepared using a template method. UV-vis diffuse reflectance spectra illustrated that the main absorption edges of the WO(3)/TiO(2) hollow spheres were red-shifted compared to the TiO(2) hollow spheres, indicating an extension of light absorption into the visible region of the composite photocatalyst. The WO(3) and TiO(2) phases were confirmed by X-ray diffraction analysis. BET isotherms revealed that the specific surface area and average pore diameter of the hollow spheres were 40.95 m(2)/g and 19 nm, respectively. Photocatalytic experiments indicate that 78% MB was degraded by WO(3)/TiO(2) hollow spheres under visible light within 80 min. Under the same conditions, only 24% MB can be photodegraded by TiO(2). The photocatalytic mineralization of MB, catalyzed by TiO(2) and WO(3)/TiO(2), proceeded at a significantly higher rate under UV irradiation than that under visible light, and more significant was the increase in the apparent rate constant with the WO(3)/TiO(2) composite semiconductor material which was 3.2- and 3.5-fold higher than with the TiO(2) material under both UV and visible light irradiation. The increased photocatalytic activity of the coupled nanocomposites was attributed to photoelectron/hole separation efficiency and the extension of the wavelength range of photoexcitation.