Facile Synthesis of Ag@AgCl Plasmonic Photocatalyst and Its Photocatalytic Degradation under Visible Light

采用简单的沉淀-光还原法合成了具有可见光催化降解有机物高活性的Ag@AgCl等离子共振光催化剂。采用扫描电镜、X射线能谱、透射电镜、XRD、紫外-可见漫反射光谱和XPS等手段对催化剂进行了表征。通过可见光下降解甲基橙进行光催化活性测试。结果显示,Ag@AgCl由于Ag纳米粒子的等离子共振效应而具有较强的吸收可见光性能。对光催化反应参数如投加量、光还原时间及pH值等进行了优化,在最优条件下,经过120 min可将83%的甲基橙降解。优异的光催化活性归因于银纳米颗粒的等离子共振效应。最后对光致电荷的分离机理进行了讨论。     

Preparation of N-Doped Bi2WO6 Microspheres for Efficient Visible Light-Induced Photocatalysis

The N-doped bismuth tungstate （BizWOt） photocatalysts with high visible light activity were prepared by the hydrothermal method using urea as a nitrogen source. The as-prepared N-doped Bi2WO6 samoles were characterized by X-ray diffraction, scanning electron microscopy, specific surface area, photocurrent analysis, and UV-Vis diffuse re- flectrance spectroscopy. The photocatalytic activity was evaluated by photocatalytic degradation of rhodamine B （RhB） solution under visible light irradiation. The photocatalytic mechanisms were analyzed by active species trapping experi- ments which revealed that the holes were the main active species of N-doped BizWO6 products in aqueous solution under visible light irradiation, rather than .OH and O-. With the assistance of H202, the photocatalytic activity for degradation of RhB could be further improved because H202 reacted with conduction band electrons to generate more hydroxyl radicals. KEY WORDS：     

掺Ag量对绢云母负载纳米二氧化钛性能的影响

以绢云母为载体,采用水解-沉淀法制备出了绢云母负载纳米TiO2粉体（TiO2/M）,在粉体表面沉积不同量的Ag2CO3,经400℃焙烧,制得不同掺Ag量的绢云母负载TiO2光催化剂,采用TG、XRD、SEM、EDS、UV等手段对样品进行了性能表征;并以日光色镝灯为光源,甲基橙为模拟污染物检测其光催化活性,研究了Ag的掺杂量对粉体中TiO2晶相结构、粒度和光催化性能的影响。结果表明：纳米TiO2均匀负载在绢云母上形成包覆层,Ag的掺杂抑制了TiO2晶粒的长大,减缓锐钛矿向金红石相的转变,同时Ag的掺杂形成新的能级结构,随Ag＋/Ti4＋摩尔比的增加,样品对光的吸收边逐渐红移至440～520 nm,具有明显的可见光响应,当Ag＋/Ti4＋=0.05时,制得样品对甲基橙的光催化降解率是没有掺Ag的样品的1.5倍,相同条件下重复利用4次,该样品60 min对甲基橙的降解率仍然可达34%。     

Synthesis and Characterization of C-TiO_2/FeTiO_3 and CQD/C-TiO_2/FeTiO_3 Photocatalysts with Enhanced Photocatalytic Activities Under Sunlight Irradiation

Sunlight-driven C-TiO_2/FeTiO_3 composites were synthesized with different weight fractions of FeTiO_3.The as-prepared samples were characterized by UV-Visible diffuse reflectance spectroscopy,Fourier transform infrared spectroscopy,X-ray diffraction analysis,transmission electron microscopy,scanning electron microscopy,energy-dispersive X-ray spectroscopy,and photoluminescence.Under sunlight irradiation,the C-TiO_2/FeTiO_3 photocatalysts degraded methyl orange(MO) efficiently and displayed much higher photocatalytic activity than that of pure FeTiO_3 or carbon-doped titanium dioxide(C-TiO_2),and the C-TiO_2/FeTiO_3 photocatalyst with 10 wt%of FeTiO_3 exhibited the highest photocatalytic activity.The enhancement of photocatalytic activity was mainly ascribed to the formation of a heterojunction between C-TiO_2 and FeTiO_3,which facilitated the transfer and separation of photogenerated electron-hole pairs.The quenching effects of different scavengers demonstrated that the reactive superoxide radicals(O_2~-) and hydroxyl radicals(OH) played a major role in the MO degradation.The possible photocatalytic mechanism is discussed on the basis of the band structures of C-TiO_2 and FeTiO_3.To further enhance the photocatalytic efficiency,double-heterojunctioned CQD/C-TiO_2/FeTiO_3 composite was prepared by loading carbon quantum dots onto the C-TiO_2/FeTiO_3 surface.     

Morphology and photocatalytic performance of nano-sized TiO_2 prepared by simple hydrothermal method with different pH values

pH value is a key factor in the preparation of nano-sized TiO_2 with hydrothermal method. Using Ti(SO_4)_2 as the titanium source, H_2O_2 as the complexing agent, NaOH and HCl as the pH value regulator, nanosized TiO_2 powder with various morphologies and sizes was synthesized. Changes in morphology, size and phase type with pH values of samples were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM) measurements. Results show that under the present preparation conditions, TiO_2 powder is an anatase phase with pH value less than 11, but is more likely to be a brookite phase with pH value more than 11. With the increase in pH value from 1 to 11 in hydrothermal environment, nano-sized anatase TiO_2 gradually grows up in all directions.{001},{101}and{100}groups of crystal plane are the exposed crystal planes of nano-sized anatase TiO_2for the (004),(101) and (200) facets found in high-resolution TEM image. The photocatalytic performance of nano-sized TiO_2 with different morphologies was compared by measuring their photocatalytic degradation rates for methylene blue under ultraviolet light. Results show that anatase TiO_2 prepared under the alkalescenthydrothermal environment (pH=9, 11) has a better photocatalytic degrading performance. Different sizes and phases of nanoscaled TiO_2 powders with different photocatalytic performances can be prepared by the control of pH value of hydrothermal solutions.     

Low-temperature synthesis of N-TiO2 sol and characterization of N-TiO2 coating on cotton fabrics

To extend the application of N-TiO₂ to substrates with low thermal resistance, N-TiO₂ sol has been successfully synthesized at low temperature by reflux method and N-TiO₂ coating on cotton fabrics has been successfully prepared in a dip-coating process. Several characterization tools, such as X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and UV–vis diffuse reflectance spectroscopy, were employed to study the phase structures, morphologies, the chemical states and optical properties of the samples. The photocatalytic properties of the prepared products were measured with the degradation of methyl orange at room temperature under visible light irradiation. In comparison with TiO₂-cotton, the remarkable enhancement in the visible light photocatalytic performance of the N-TiO₂-cotton could be attributed to the existence of N-TiO₂ with narrow band gap. The photocatalytic performances of the N-TiO₂-cotton were maintained for the cycling experiments, indicating that N-TiO₂-cotton could be used as stable and efficient visible-light-induced self-cleaning materials.     

Preparation of TiO<Subscript>2</Subscript> Nanopowders by Plasma Spray and Characterizations

TiO₂ powders with the range of 10-60 nm were prepared successfully by plasma spray in the self-developed plasma spray equipment. The prepared nanopowders were characterized by transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The results showed that the prepared TiO₂ nanopowders were the mixture of anatase phase and rutile phase, the main phase was anatase. There were O, Ti, and C elements in powders; Ti element still existed in tetravalent. The photocatalytic degradation of methyl orange indicated that all methyl orange (20 mg/L) can be degraded fully when the addition of prepared TiO₂ nanopowders and illumination time were 1 g/L and 150 min, respectively.     

无模板剂的溶胶-水热法合成具有可见光响应的氮掺杂混晶 TiO2(锐钛矿/金红石/板钛矿)纳米棒束

采用无模板剂的溶胶-水热法制备了具有可见光响应的N掺杂锐钛矿/金红石/板钛矿型TiO_2(N-TiO_2)纳米棒束,并利用X射线衍射(XRD)、透射电镜(TEM)、紫外-可见光漫反射光谱(UV-Vis DRS)、傅里叶变换红外光谱(FTIR)和X射线光电子能谱(XPS)等手段对获得的样品进行了表征。以甲基橙为模型反应物,评价了N-TiO_2纳米棒束的光催化活性。表征结果结合光催化活性评价结果显示,与P25-TiO_2相比,N掺杂、混晶及纳米棒束之间的协同作用是所制备的混晶N-TiO_2纳米棒束具有良好光催化活性的主要原因,并对混晶N-TiO_2纳米棒束光催化降解甲基橙的机理进行了探讨。     

钛粉制备多级纳米结构TiO_2微球及其光催化特性

在NaOH溶液中采用水热法处理钛粉制备TiO2纳米针/带微球。利用场发射扫描电子显微镜（FESEM）、透射电子显微镜（TEM）、选区衍射（SAED）、紫外-可见吸收光谱（UV-vis）和X射线衍射仪（XRD）对样品结构进行表征。结果显示,水热温度和溶液浓度共同决定晶体的生长方向,纳米针/带微球的直径（40~50μm）与钛粉直径相当。纳米针/带微球经450°C热处理1h后转变锐钛矿。以甲基橙为目标考察样品的光催化活性。在相同条件下,样品的光催化活性为：TiO2纳米针微球〉TiO2纳米带微球〉P25。     

Electrodeposition of photocatalytic TiO2 film on surface of alumina prepared by anodic oxidation

A new electrochemical method to prepare photocatalytic TiO2 thin film was developed, by which the TiO2 was electrodeposited on surface of alumina by AC electrolysis in solution consisting of K2 [TiO(C2O4 )2] and C2H2O4. The deposited TiO2 thin film was primarily characterized by X-ray diffraction (XRD), scanning electronic microscopy (SEM) and energy dispersive spectrum (EDS) methods. The photocatalytic properties of this film were also studied by the photocatalytic degradation of methyl orange. The results show that the TiO2 film electrodeposited by this method is mainly in amorphous and with a little crystalline component mixed anatase and rutile. The surface of the alumina prepared by anodic oxidation is porous and the TiO2 electrodeposited on it is scattered and incompact. TiO2 thin film fixed on the surface of alumina shows photocatalytic activity to the degradation of methyl orange.     

纳米二氧化钛粉体的光催化性能

以紫外灯为光源,采用TiO_2悬浮体系,利用分光光度法,研究了各种实验条件对光催化效果的影响。结果表明:光强、甲基橙的初始浓度、TiO_2的浓度和晶型、溶液pH以及掺杂离子等对降解效率都有较大的影响。     

Preparation of mesoporous titania particles using ionic liquid dissolving starch as templates

A mesoporous titania photocatalyst was prepared via calcining the solution of ionic liquid (1-methyl-3-butyl imidazolium bromide, [BMIM]Br) containing tetrabutyl titanate (TBT) and starch. The microstructure of the prepared mesoporous titania was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and N₂ adsorption/desorption isotherm. The results indicate that the resulting mesoporous titania has a grain size of about 13.9 nm, a special surface area of 106 m²/g, and a pore volume of 0.22 cm³/g, and the pore size can be adjusted by the concentration of starch in ionic liquid. The photocatalytic activity of mesoporous titania in the degradation of methyl orange solution was determined. The effect of the specific surface area of mesoporous titania on the photocatalytic activity was also studied. The prepared mesoporous titania exhibits a high catalytic activity.     

Enhanced photocatalytic properties of ultra-long nanofiber synthesized from pure titanium powders

Using Ti powder as reagent,ultra-long TiO2 nanofibers were prepared via hydrothermal method in NaOH solution.The samples were char-acterized respectively by means of field emission scanning electron microscopy (FESEM),transmission electron microscopy (TEM) with selected area electron diffraction (SAED),and X-ray diffraction (XRD).The diameter and the length of the ultra-long TiO2 nanofiber were ～100 nm and >200μm,respectively.The ultra-long TiO2 nanofibers were anatase after heat treatment at 450 ?C for 1 h.Moreover,the optical properties of the products were investigated by UV-visible light absorption spectrum.Furthermore,methyl orange was used as a target molecule to estimate the photocatalytic activity of the specimens.Under the same testing conditions,the photocatalytic activity of the ultra-long TiO2 nanofibers was higher than that of P25.Direct electrical pathway and improved light-harvesting efficiency were crucial for the superior photocatalytic activity of the ultra-long TiO2 nanofibers.     

Enhancing visible-light activity of the self-cleaning TiO2-coated cotton fabrics by loading AgI particles

While extending the application of TiO₂ to substrates with low thermal resistance, enhanced visible-light activity of the self-cleaning TiO₂-coated cotton fabrics has been realized by loading AgI particles. Several characterization tools, such as X-ray powder diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and UV-vis diffuse reflectance spectroscopy, were employed to study the phase structures, morphologies and optical properties of the samples. The photocatalytic properties of the prepared products were measured with the degradation of methyl orange at room temperature under visible light irradiation. In comparison with TiO₂-cotton fabrics, the dramatic enhancement in the visible light photocatalytic performance of the AgI-TiO₂-cotton fabrics could be attributed to AgI with narrow band gap and the effective electron-hole separations at the interfaces of the two semiconductors. The photocatalytic performances of the AgI-TiO₂-cotton fabrics were maintained for the cycling experiments. In addition, based on the XRD patterns of the AgI-TiO₂-cotton fabrics before and after reaction, AgI was stable in the composites under visible irradiation, indicating that AgI-TiO₂-cotton fabrics could be used as stable and efficient visible-light-induced self-cleaning materials.     

Novel AgCl/Ag<Subscript>2</Subscript>CO<Subscript>3</Subscript> heterostructured photocatalysts with enhanced photocatalytic performance

A series of novel AgCl/Ag₂CO₃ heterostructured photocatalysts with different AgCl contents (5 wt%, 10 wt%, 20 wt%, and 30 wt%) were prepared by facile coprecipitation method at room temperature. The resulting products were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS), respectively. The photocatalytic activity of the samples was evaluated by photocatalytic degradation of methyl orange (MO) under UV light irradiation. With the optimal AgCl content of 20 wt%, the AgCl/Ag₂CO₃ composite exhibits the greatest enhancement in photocatalytic degradation efficiency. Its first-order reaction rate constant (0.67 h^?1) is 5.2 times faster than that of Ag₂CO₃ (0.13 h^?1), and 16.8 times faster than that of AgCl (0.04 h^?1). The formation of AgCl/Ag₂CO₃ heterostructure could effectively suppress the recombination of the photo-generated electron and hole, resulting in an increase in photocatalytic activity.     

Fabrication of Mono-dispersed Hollow Titania Nanospheres with Enhanced Photocatalytic Property

采用阳离子聚苯乙烯(PS)微球为模板,以钛酸丁酯为前驱体经溶胶凝胶反应制备了TiO2/PS复合微球,并经高温煅烧得到单分散中空TiO2纳米微球。采用扫描电镜(SEM)、透射电镜(TEM)、红外光谱仪(FT-IR)、X射线衍射仪(XRD)和紫外-可见分光光度计(UV-VIS DRS)对复合和中空微球的结构和光催化性能进行了表征。结果表明,经高温煅烧后TiO2中空微球尺寸相对于复合微球收缩了约25%,其粒径约为100 nm;中空微球壳层厚度可随钛酸丁酯用量而变化,壳层呈锐钛矿和金红石混晶结构,同时中空微球表现出比P25纳米TiO2更强的甲基橙光降解特性。     

Phase Characterizations and Photocatalytic Applications of CuO-K_2Mo_4O_(13) Composites

A series of CuO-K_2Mo_4O_(13)composite materials have been prepared by mixing appropriates quantities,in solid state,of CuO and pure K_2Mo_4O_(13) according to the molar ratios CuO/K_2Mo_4O_(13) = 0.05,0.1,0.2,0.5,and 1.The prepared samples were characterized using techniques such as X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FT-IR),differential thermal analysis(DTA),nitrogen adsorption measurements,and UV spectroscopy.According to XRD results,the phase composition of the CuO-K_2Mo_4O_(13) systems has significantly changed by increasing the molar ratio CuO/K_2Mo_4O_(13) where new phases,identified as K_2Mo_3O_(10) and CuMoO_4,have been detected.The formation of these new phases has been tracked through FT-IR and DTA measurements.The nitrogen adsorption-desorption measurements also reveal a change in the pore type of me studied materials due to the presence of these new phases.The photocatalytic activities of K_2Mo_4O_(13) and CuO-K_2Mo_4O_(13) composites were studied by means of monitoring the ability of these materials to the degradation,under UV irradiation,of methyl red in liquid media.It was found that the phase composition of the used samples significantly controls their photocatalytic activities.     

Visible Light Photocatalysis of Ni-Deposited TiO_2 Nanotubes for Methyl Orange Degradation in Alkaline Medium

The photocatalysis of Ti O2nanotubes(Ti/TNT) and Ni-deposited Ti O2nanotubes(Ti/TNT–Ni) for methyl orange degradation was investigated.Methyl orange was selected as the model pollutant,and its photocatalytic degradation was determined in 1 mol/L KOH solution.Ti/TNT was produced by anodizing method,and the electrodeposition of nickel on TNT was performed galvanostatically.The characterization of electrodes was performed by scanning electron microscopy,energy-dispersive X-ray spectroscopy and X-ray diffraction analysis.The electrochemical behavior of the electrodes was determined by cyclic voltammetry and electrochemical impedance spectroscopy.The irradiation was applied by visible light source(k = 635 nm) for 48 h.UV/vis spectroscopy was used for determination of the concentration of methyl orange.Furthermore,after 48-h irradiation,the solutions were analyzed by Fourier transform infrared spectroscopy.Results showed that the concentration of methyl orange decreased from 100 ppm(10-6) to 16 ppm,after48-h irradiation with the photocatalysis of Ti/TNT–Ni.     

室温水溶液法制备 Cu2O 纳米颗粒及其光催化性能

以乙酸铜为铜源,β-环糊精为表面活性剂,NaOH为添加剂,KBH4为还原剂,在室温水溶液中制备了直径约为50 nm的Cu2O,对产物的组成、能隙、光催化性能进行了分析。研究表明:产物结晶性良好,粒径分布较均匀,且产率高;此外,该纳米Cu2O由于比表面积大,对甲基橙在30 min内的催化效率高达94.9%,甲基橙几乎全部被降解,显示出良好的催化活性。