TiO2/聚苯胺复合材料的合成、结构表征及光催化性能

在室温下,以苯胺为单体、钛酸四丁酯为反应物,通过化学氧化原位聚合和溶胶-凝胶的方法制备了TiO2/聚苯胺复合材料。利用X-射线衍射仪、傅立叶变换红外光谱仪、紫外-可见吸收光谱仪、热失重分析仪等对复合材料表面的微观结构及热稳定性进行了表征。通过光催化降解甲基橙实验评价了TiO2/聚苯胺复合光催化剂在紫外光条件下的光催化活性,实验表明,TiO2/聚苯胺复合材料的催化效率大大提高,特别是TiO2/聚苯胺(质量比例为1/2)复合材料对甲基橙的降解效率最高达到85.7%。     

Preparation and photocatalytic properties of nanometer-sized magnetic TiO2/SiO2/CoFe2O4 composites

Magnetic TiO2/SiO2/CoFe2O4 nanoparticles (TiO2/SCFs) were prepared by a sol-gel process in a reverse microemulsion combined with solvent-thermal technique. TiO2/SCFs were characterized by Fourier transform infrared spectrometry, thermogravimetric analysis-differential scanning calorimetry, X-ray diffraction, Raman spectrometry, TEM, BET specific surface area measurement, and magnetic analysis. Structure analyses indicated that TiO2/SCFs presented a core-shell structure with TiO2 uniformly coating on SiO2/CoFe2O4 nanomagnets (SCFs) and typical ferromagnetic hysteresis. TiO2/SCFs showed larger specific surface area and better photocatalytic activities than TiO2 and TiO2/CoFe2O4 photocatalysts prepared by the same method. The doping interaction between TiO2 and CoFe2O4 reduced thanks to the inert SiO2 mesosphere.     

Hydrothermal synthesis and photocatalytic activity of anatase TiO2 nanofiber

TiO2 nanofiber consisting of 15 +/- 5 nm anatase grains was synthesized by hydrothermal treatment of fibrous hydrogen titanate precursor at 180 degrees C for 20 h. The hydrogen titanate precursor was synthesized by hydrothermal treatment of commercial P25 TiO2 powder in 10 M NaOH at 200 degrees C for 20 h followed by soaking in 0.1 M HNO3 to perform ion exchange between the as-synthesized Na titanate and H. By controlling pH of the solution during hydrothermal treatment of the hydrogen titanate precursor, pure anatase TiO2 nanofiber was obtained. Its band-gap energy determined from the onset of diffused reflectance spectrum was 3.19 eV which is equal to that of anatase TiO2 powder. The TiO2 nanofiber showed higher photodecomposition efficiency than the Cotiox KA-100 TiO2 but lower than the P25 TiO2. Photodegradation is the predominant process for 'Reactive blue 171' removal.     

N与La共掺杂纳米TiO_2/电气石复合材料的制备及其光催化性能

采用超声辅助溶胶-凝胶法,以钛酸丁酯为原料,尿素为N源,硝酸镧为La源,制备了N与La共掺杂纳米TiO_2/电气石复合材料。采用XRD、UV-Vis、SEM-EDS和XPS对复合材料的结构和性能进行了表征。以2,4,6-三硝基甲苯作为目标污染物,考察了N与La共掺杂纳米TiO_2/电气石复合材料的光催化活性及再生利用性能。结果表明:N与La共掺杂并负载电气石后,两者协同作用使TiO_2晶粒更加细化,光吸收范围向可见光区拓展,N与La共掺杂纳米TiO_2/电气石复合材料具有良好的光催化活性和再生利用性能,且在模拟可见光照射条件下对2,4,6-三硝基甲苯具有良好的去除效果。     

Synthesis and photocatalytic property of SnO2/TiO2 nanotubes composites

SnO2/TiO2 nanotubes composite photocatalysts with different SnO2 contents were successfully synthesized by means of a simple solvothermal process. The synthesized products were characterized physically by X-ray diffraction (XRD) and high-resolution transmission electron microscope (HRTEM). The composite photocatalysts can not only make the target pollutant, methylene blue (MB), adsorbed at a high concentration level around the surface of the composites but also decrease the recombination rate of electron-hole pairs so as to achieve good photocatalytic performance. The effect of SnO2 contents on the photocatalytic activities of the composites was also investigated. The results showed that the SnO2/TiO2 nanotubes composite photocatalyst with 5 wt.% SnO2 loading had the highest photocatalytic efficiency.     

具有可见光活性的TiO2薄膜的制备及光催化性能

运用磁控溅射技术在浸渍－提拉法制得的TiO2薄膜上溅射三氧化钨层得到光催化薄膜。采用SEM、XRD、AES、UV－vis漫反射光谱等方法表征催化剂薄膜的厚度、晶相结构、化学元素组成及光吸收性能。以甲基橙的光催化降解为反应模型，高压汞灯为光源，溅射有三氧化钨薄膜的光催化活性低于纯TiO2薄膜；滤过紫外光后，溅射有三化钨的薄膜光催化活性明显高于纯TiO2薄膜。本实验提供了一种制备高可见光活性的TiO2薄膜的方法。     

Controlled synthesis of anatase TiO2 octahedra with enhanced photocatalytic activity

Titanium dioxide (TiO₂) nanocrystals with specific exposed crystal facet have attracted considerable interest due to their promising applications in the fields of energy and environment. In this paper, we report on a simple solvothermal approach for the synthesis of anatase TiO₂ octahedra with high yield, using titanium(IV) sulfate and hydrazine hydrate as the starting materials. The formation mechanism of anatase TiO₂ octahedra is suggested. The samples were characterized with XRD, Raman, SEM, TEM, FTIR, XPS, and UV/vis techniques, and further tested as a candidate in photocatalysis to decompose methyl orange in aqueous solution at room temperature. The results show that SO₄²⁻ ions not only benefit the formation of octahedral nanocrystals, but also inhibit nitrogen doping into TiO₂ matrix. More importantly, it is found that the octahedral TiO₂ nanocrystals show enhanced photocatalytic activity compared to TiO₂ P25 and anatase TiO₂ counterparts.     

Anatase TiO2 nanoparticles/carbon nanotubes nanofibers: preparation, characterization and photocatalytic properties

In the present work, we report the preparation and photocatalytic properties of hybrid nanofibers/mats of anatase TiO₂ nanoparticles and multi-walled carbon nanotubes (MWNTs) using combined sol–gel and electrospinning techniques. Poly(vinyl pyrrolidone) is used as a base polymer in the electrospinning suspension to assist the formation of nanofibers and subsequently removed by calcination. The hybrid nanofibers are characterized using XRD, Raman spectra, FT-IR, XPS, SEM, TEM and N₂ adsorption measurements. The results show that MWNTs are encapsulated by in-situ formed anatase TiO₂ nanoparticles, with chemical bonding C–O–Ti between anatase TiO₂ nanoparticles and MWNTs. Hybrid nanofibrous mats with moderate content of MWNTs (mass ratio TiO₂:MWNTs = 100:20) exhibit enhanced adsorption ability and excellent photocatalytic activity. The composition, diameter and morphology of hybrid nanofibers can be tuned by varying sol–gel formulation, electrospinning parameter and post-treatment condition. TiO₂/MWNTs hybrid nanofiber and mats have promising applications in water purification and solar cell areas.     

Preparation, characterization and photocatalytic activity of TiO2/polyaniline core-shell nanocomposite

Polyaniline (PANI) as a promising conducting polymer has been used to prepare polyaniline/TiO₂ (PANI/TiO₂) nanocomposite with core-shell structure as photocatalyst. Titanium dioxide (TiO₂) nanoparticles with an average crystal size of 21?nm were encapsulated by PANI via the in situ polymerization of aniline on the surface of TiO₂ nanoparticles. FT?CIR, UV-Vis-NIR, XRD, SEM and TEM techniques were used to characterize the PANI/TiO₂ core-shell nanocomposite. Photocatalytic activity of PANI/TiO₂ nanocomposite was investigated under both UV and visible light irradiations and compared with unmodified TiO₂ nanoparticles. Results indicated deposition of PANI on the surface of TiO₂ nanoparticles which improved the photocatalytic activity of pristine TiO₂ nanoparticles.     

High-yield synthesis of well-crystalline alpha-Fe2O3 nanoparticles: structural, optical and photocatalytic properties

In this paper, the high-yield facile synthesis, detailed characterization and photocatalytic application of alpha-Fe2O3 nanoparticles are reported. The synthesis was done via simple hydrothermal process by using aqueous mixtures of iron chloride, hexamethylenediamine and NH3 x H2O at 110 degrees C. The morphologies of the synthesized products were examined by using field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) which confirmed that the synthesized structures are almost spherical shaped nanoparticles with the average diameters of -35 +/- 5 nm, and are grown in high yield. The detailed structural characterizations and composition of the as-synthesized nanoparticles were investigated by using X-ray diffraction (XRD), high-resolution TEM (HRTEM), energy dispersive spectroscopy (EDS) attached with FESEM and Fourier transform infrared spectroscopy (FTIR) which substantiated that the as-synthesized nanoparticles are well crystalline and pure alpha-Fe2O3. The UV-Vis absorption spectrum of the synthesized nanoparticles demonstrated the existence of two optical band gaps which correspond to direct and indirect transitions, respectively. The as-synthesized alpha-Fe2O3 nanoparticles exhibit good photocatalytic properties on photocatalytic degradation of methylene blue.     

纳米复合材料TiO2/ZnFe2O4的制备及光催化性能

用高分子网络凝胶法制备TiO2/ZnFe2O4纳米复合材料,研究了掺杂ZnFe2O4对TiO2平均粒径、晶型及其光催化性能的影响.结果表明,掺杂的ZnFe2O4纳米晶高度分散、均匀地分布在TiO2表面,促进了TiO2向稳定的金红石相转变,并抑制了晶粒的长大.ZnFe2O4掺杂量为2%的TiO2/ZnFe2O4粉体在500℃煅烧后,在可见光范围内具有最佳的次甲基蓝降解效果,降解率达到100%.ZnFe2O4的掺杂扩展了TiO2的光谱响应范围.     

V-N共掺杂TiO_2/玻璃珠光催化复合材料的制备及光催化性能

用溶胶-凝胶法制备V-N-TiO_2/玻璃珠光催化复合材料,研究V-N-TiO_2(V-N-TiO_2)的浓度、V-N-TiO_2/玻璃珠的浸渍次数、玻璃珠尺寸、煅烧温度和煅烧时间对V-N-TiO_2/玻璃珠光催化复合材料光催化性能的影响。采用XRD、EDS、TEM、XPS等测试手段对复合材料的结构和性能进行表征;在100 W汞灯下,以苯酚溶液为目标降解物,对V-N-TiO_2/玻璃珠光催化复合材料光催化性能进行测定。研究表明:当V-N-TiO_2/玻璃珠的浸渍次数为4次、玻璃珠尺寸为2~3mm、煅烧温度为400℃和煅烧时间为4.5h时,得到的V-N-TiO_2/玻璃珠光催化复合材料对苯酚的光催化性能最佳,且单位催化剂对苯酚的降解量略高于V-N-TiO_2。V-N-TiO_2/玻璃珠光催化复合材料既易于回收,又具有良好的光催化性能。     

TiO2/clinoptilolite composites for photocatalytic degradation of anionic and cationic contaminants

The present work aims to study the bulk and surface properties of the TiO₂/clinoptilolite composite on the crystalline structure, superficial area, bandgap energy, zeta potential, particle size distribution, and chemical composition; in order to analyze the effect of the clinoptilolite proportion in the photocatalytic degradation of pollutants. TiO₂/clinoptilolite composites were prepared by adding different mass proportions of clinoptilolite to a sol–gel bath containing TiCl₄ as the titania precursor. Surface charge studies explain the larger sensitivity to composite ratio observed in the photocatalytic degradation of anionic pollutants than in cationic dyes. An optimum TiO₂/clinoptilolite ratio of 90/10 was found to be the most efficient in terms of lower tendency to agglomeration, largest surface area, and increased crystallite size. Improvement in composite surface area occurs only at low clinoptilolite wt% and seems to be caused by lower agglomeration of nanometric TiO₂ and acid-induced porosity in the zeolite.     

Br-N共掺杂TiO_2/磁性炭复合材料的制备及其可见光催化性能

以活性炭(AC)为原材料,采用铁盐化学沉淀法耦合壳聚糖-戊二醛交联改性技术制备磁性活性炭(MAC)。以MAC为载体,采用溶胶-凝胶法制备不同Br/Ti掺杂比的Br-N共掺杂TiO_2/MAC可见光催化复合材料(Brx-N-TiO_2/MAC)。通过XRD、UV-Vis漫反射、BET吸附实验、SEM、XPS表征其结构和化学特征。以水杨酸为模型分子进行光催化降解,评价不同Brx-N-TiO_2/MAC材料的可见光催化活性。实验结果表明,相较于N-TiO_2/MAC可见光催化剂,Br-N共掺杂更能促进催化剂对可见光的吸收。Br_(0.35)-N-TiO_2/MAC对水杨酸的降解效果最好,暗吸附1h、光催化3h后,Br_(0.35)-N-TiO_2/MAC对水杨酸的降解率达到83%,高浓度水杨酸会对光催化反应产生一定的抑制作用,该催化材料重复利用三次后仍有78%的去除率,显示了较好的稳定性。     

Nanoscale ZnS/TiO2 composites: Preparation, characterization, and visible-light photocatalytic activity

Photoactive ZnS/TiO₂ nanocomposites were prepared via microemulsion-mediated solvothermal method. The structure, composition, physicochemical property, and morphology of the composites were characterized by powder X-ray diffraction (XRD), Raman scattering studies, UV diffuse reflectance spectroscopy (UV/DRS), photoluminescence (PL) spectroscopy, and transmission electron microscopy (TEM). It showed that the composites were cube-shaped with particle sizes of 10 to 15 nm, and the phase structure for ZnS and TiO₂ in the composites was cubic and anatase, respectively. The content of the ZnS in the composites was 2.1%, 10.7%, and 19.9%, respectively. Compared with the solitary anatase TiO₂, the ZnS/TiO₂ exhibited enhanced visible-light photocatalytic activity for the aqueous parathion-methyl degradation. Factors including the interactions between the phases of ZnS and TiO₂, strong adsorption of the substrate at the surface of the ZnS/TiO₂ nanocomposites, and preassociation of the substrate and composites are responsible for this enhancement photocatalytic activity.     

Controllable synthesis and enhanced photocatalytic properties of Cu2O/Cu31S16 composites

The controlled synthesis of Cu₂O/Cu₃₁S₁₆ microcomposites with hierarchical structures had been prepared via a convenient sonochemical route. Ultrasonic irradiation of a mixture of Cu₂O and (NH₂)₂CS in an aqueous medium yielded Cu₂O/Cu₃₁S₁₆ composites. The content of Cu₃₁S₁₆ in the Cu₂O/Cu₃₁S₁₆ can be easily controlled by adjusting the synthesis time. The Cu₃₁S₁₆ layer not only protected and stabilized Cu₂O particles, but also prohibited the recombination of photogenerated electrons–holes pair between Cu₃₁S₁₆ and Cu₂O. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) spectra, ultraviolet–visible (UV–Vis) spectroscopy and photoluminescence (PL) spectroscopy were used to characterize the products. Photocatalytic performance of the Cu₂O/Cu₃₁S₁₆ hierarchical structures was evaluated by measuring the decomposition rate of methyl orange solution under natural light. To the best of our knowledge, this is the first report on the preparation and photocatalytic activity of Cu₂O/Cu₃₁S₁₆ microcomposite. Additionally, the Cu₂O/Cu₃₁S₁₆ core/shell structures were more stable than single Cu₂O particles during photocatalytic process since the photocatalytic activity of the second reused architecture sample was much higher than that of pure Cu₂O. The Cu₂O/Cu₃₁S₁₆ microcomposites may be a good promising candidate for wastewater treatment.     

两步水热法制备还原氧化石墨烯/纳米TiO_2复合材料及其光催化性能

为研究由还原氧化石墨烯(RGO)和具有高活性晶面的TiO_2组成的复合材料的制备方法及其光催化性能,首先采用两步水热法制备了RGO/纳米TiO_2复合材料:第1步为合成暴露高活性晶面的纳米TiO_2;第2步为将合成的纳米TiO_2与氧化石墨烯(GO)复合,形成RGO/纳米TiO_2复合材料。然后,利用XRD、SEM、X射线光电子能谱仪和紫外-可见漫反射光谱等手段对制备的暴露不同晶面的纳米TiO_2和RGO/纳米TiO_2复合材料进行了表征,评价了其光催化性能。结果表明:在水热法的第1步中,通过调节HF的浓度能可控制备出具有高活性的(001)和(101)晶面的纳米TiO_2,氟原子在纳米TiO_2中以物理吸附态和化学结合态这2种形态存在;在第2步后,GO与纳米TiO_2复合形成RGO/纳米TiO_2复合材料,同时在此过程中GO被转化成RGO。在紫外光照射下,两步水热法合成的RGO/纳米TiO_2复合材料具有很好的光催化性能,明显优于商用TiO_2(P25)和纳米TiO_2的。RGO/纳米TiO_2复合材料的光催化性能有明显的提高,RGO和TiO_2暴露的晶面对光催化活性有影响。