Bi_2O_3-MgO复合材料的制备及其光催化性能研究

通过凝胶-溶胶法制备了Bi2O3-MgO复合材料,用可见光降解罗丹明B,考察了n(Bi)∶n(Mg)、反应温度、活化时间以及煅烧温度等因素对Bi2O3-Mg O光催化性能的影响,并得出最佳制备条件:n(Bi)∶n(Mg)=2,反应温度90℃、活化时间15 h,煅烧温度500℃。     

Bi@Bi4Ti3O12/TiO2 films on glass with photocatalytic and self-cleaning performance

A stable and translucent Bi@Bi₄Ti₃O₁₂/TiO₂ film was fabricated on conventional glass substrates for the first time. The film exhibited a good photocatalytic performance and efficient self-cleaning capability against organic dyes under full spectral irradiation and visible light irradiation. Bi₄Ti₃O₁₂/TiO₂ film was first prepared on a glass substrate with colloidal silica as a high temperature binder, followed by implantation of nanoscale Bi in it by an in-situ partially reduction of Bi₄Ti₃O₁₂ to generate Bi@Bi₄Ti₃O₁₂/TiO₂ films. The improved photocatalytic ability is probably attributed to the surface plasmon resonance of Bi atom as well as the enhanced electron transfer efficiency and synergistic effect of Bi₄Ti₃O₁₂ and TiO₂. According to trapping experiments, hydroxyl radicals (OH) were active species in the photocatalytic degradation of dyes under full spectral light irradiation and possible photocatalytic mechanism was proposed. The film prepared in this work may well have potential practical applications in many aspects, such as cleansing treatments for high building external decorative panels and also systematic characterization of the film suggests that the in-situ reduction is an effective and simple way to produce nanoscale Bi@Bi₄Ti₃O₁₂.     

Synthesis,structural characterization,and photocatalytic activity of Bi‐based nanoparticles

Bi‐based nanoparticles were successfully synthesized (500°C/2 h) following two intermediate‐temperature routes, Pechini and a combined method of mechanical milling/molten salts. Herein, α‐Bi₂O₃/Bi₂O₂CO₃ heterostructures were identified. These types of heterostructures have shown advantages to improve the visible light responsive activity of Bi‐based nanoparticles to facilitate the separation of photogenerated electron‐hole pairs. By fixing the experimental parameters, the synthesis route and Ag contents showed to play a very important role in the phase composition of the Ag‐containing samples; the formation of Bi/Ag‐Bi₂O₃/Bi₂O₂CO₃ and Ag/Ag‐Bi₂O₃/Bi₂O₂CO₃ complex hybrid structures were revealed. The α‐Bi₂O₃/Bi₂O₂CO₃ heterostructure prepared by combined method exhibited higher photocatalytic efficiency (66.84%) for degrading methylene blue (MB) depending on Bi₂O₂CO₃ component proportion. For the Ag‐containing hybrid structures, the performance of their catalytic activity did not show an increase with respect to α‐Bi₂O₃/Bi₂O₂CO₃. However, in these samples, the degradation efficiency was slightly enhanced with the efficient doping of Ag into the α‐Bi₂O₃ structure and the existence of Bi when the Pechini method was used. Also, a possible photocatalytic process for degrading MB is presented.     

纳米TiO2-Bi2O3-La2O3复合材料的制备及光、电催化性能研究

以钛酸丁酯、硝酸铋、硝酸镧为主要原料,溶胶-凝胶法分别制备了TiO2、TiO2-Bi2O3、TiO2-La2O3和TiO2-Bi2O3-La2O3等催化剂。用XRD、TEM等方法对其进行了表征,晶型均为锐钛矿,粒径范围10~25 nm。以罗丹明B为目标降解物,分别考察了催化剂的光、电催化活性。结果表明,在紫外光照下,TiO2-Bi2O3-La2O3的光催化活性最高,60 min时罗丹明B的降解率达98.7%,较纯TiO2光催化活性提高了162%;以负载TiO2-Bi2O3-La2O3的多孔材料为粒子电极,采用三维电极法降解罗丹明B,20 min时的降解率达98.6%,较使用负载纯TiO2粒子电极提高了9%。     

超亲水性介孔SiO2/Bi2O3/TiO2分层薄膜的制备及其自洁净性能研究

采用溶胶-凝胶/旋转涂覆法在玻璃基板表面制备介孔SiO2/Bi2 O3/TiO2分层薄膜.采用XRD、UV-vis及表面接触角测量仪对薄膜的结构、透光性及超亲水性进行分析.结果表明,介孔SiO2/Bi2 O3/TiO2分层薄膜仍然保持了表面SiO2的介孔结构,在无光照条件下仍具有超亲水性.涂有硬脂酸的薄膜在紫外光照射后恢复了其超亲水性,具有良好的自洁净性能.且SiO2/Bi2 O3/TiO2分层薄膜表现出比单独的SiO2/TiO2和SiO2/Bi2O3分层薄膜更高的光催化活性.     

Generation of hydrogen under visible light irradiation with enhanced photocatalytic activity of Bi2WO6/Cu1.8Se for organic pollutants under Vis‐NIR light reign

To make better use of solar light, a new Bi₂WO₆/Cu_1.8Se photocatalyst active to visible and near‐infrared light has been synthesized by a facile hydrothermal method. The composites were characterized by X‐ray diffractometry (XRD), scanning electron microscopy (SEM), UV‐vis diffuse reflectance spectroscopy (DRS), and photoluminescene (PL). The photocatalytic activities of Bi₂WO₆/Cu_1.8Se are evaluated by degrading Congo red solution and hydrogen generation from water. It was found that the molar percentage of Cu_1.8Se had great effects on the morphology and photocatalytic property of the Bi₂WO₆/Cu_1.8Se heterojunctions, and the composite with suitable molar amount of Cu_1.8Se exhibits much enhanced photocatalytic activity for Congo red degradation under visible and near‐infrared light irradiation and for hydrogen generation under visible light compared to Bi₂WO₆. The significant improvement photocatalytic activity of the composite could be attributed to its good light absorption, suitable band gap structure, and effective separation of photogenerated electron‐hole pairs of Bi₂WO₆/Cu_1.8Se heterojunction. This work presents an efficient multifunction photocatalyst owning the activity both for water splitting under visible light and for organic contaminants decomposition under visible‐near‐infrared light.     

海泡石负载Bi_2O_3对孔雀石绿光催化降解性能研究

以海泡石为载体,采用化学沉淀法制备了负载型Bi_2O_3光催化剂。通过XRD、SEM、TEM、UV-vis对光催化剂进行了表征。以孔雀石绿为模型降解物考察了光催化剂的光催化活性,重点研究了光催化剂投加量、孔雀石绿溶液初始pH及溶液初始浓度对降解效果的影响。结果表明:当光催化剂投加量为1.0 g/L,孔雀石绿溶液初始pH为7,溶液初始质量浓度为50 mg/L,光照30 min,孔雀石绿的降解率达到95.7%,孔雀石绿溶液初始浓度越高,越不容易被降解,但光照60 min,所有浓度的孔雀石绿基本降解完毕,通过重复实验发现,该负载型Bi2O3的稳定性较高。     

一种新颖Fe~(3+)/TiO_2薄膜的制备及光催化性能研究

用溶胶-凝胶法制备了纳米Fe3+/TiO2,以琼脂糖为载体,采用水热法合成纳米Fe3+/TiO2的琼脂糖凝胶。以降解转移因子制药废水为反应模型,研究了纳米Fe3+/TiO2琼脂糖凝胶薄膜的紫外光照射的催化活性及薄膜的重复使用效果。结果表明,纳米Fe3+/TiO2薄膜光催化活性明显较粉体的强,且不易失活,再生性能好,薄膜重复使用5次以上,仍有明显的降解效果。     

Co3O4-Bi2O2CO3催化剂的制备及其光催化性能

以Bi(NO₃)₃·5H₂O、Co(CH₃COO)₂·4H₂O为原料,采用化学沉淀-水热法制备了Co₃O₄-Bi₂O₂CO₃异质结构复合半导体光催化剂,并通过X射线衍射仪（XRD）、扫描电镜（SEM）、X射线光电子能谱（XPS）、紫外可见漫反射光谱（DRS）、荧光光谱（PL）等手段对所合成的复合型催化剂进行了理化性能表征。研究结果表明：引入Co₃O₄没有改变Bi₂O₂CO₃物相结构,但促进了Bi₂O₂CO₃ 对可见光的吸收能力,提高了Bi₂O₂CO₃表面吸附氧物种的数量,抑制了光生载流子复合。复合光催化剂对罗丹明B（RhB）的光催化脱色实验显示引入Co₃O₄能够明显提高Bi₂O₂CO₃催化剂的光催化脱色能力。尤其是Co₃O₄引入量为0.6%的Co₃O₄-Bi₂O₂CO₃样品对罗丹明B染料的光催化脱色率可达到97%（模拟日光照射30min）。本文为复合型光催化剂制备提供了简单易行的技术路线,制备的新型半导体复合光催化剂Co₃O₄-Bi₂O₂CO₃在环境净化方面表现出了较好的应用前景。     

Anticorrosion assessment of Al2O3‐TiO2 composite thin films derived from sol‐gel dipping technique

Metal surface protection by means of nanostructured ceramic coatings is considered an issue, which is variously scrutinized, and more efforts are made to improve steel performance in accordance with this method. In this respect, this study sought to examine the protective effects of a nanostructured coating containing TiO₂ and Al₂O₃. The optimization approach for obtaining a coating without any cracks with the highest efficiency of corrosion resistance is reported. The variables under assessment were as follows: weight ratio of the oxides, calcination temperature, and preparation parameters. The synthesized samples were analyzed utilizing XRD, FESEM, AFM, Tafel test, EIS, and microhardness measurement. The results revealed that the optimized conditions were as follows: (i) Ti:Al precursor mixture with a weight ratio of 75:25, (ii) heat treatment at 1000°C. This process yielded a uniform composite coating without any cracks with 5.1 nm roughness, containing crystalline rutile phase and amorphous alumina. Not only the intended coating improves the corrosion resistance of steel up to 97%, but it also increases its surface hardness up to 10 units.     

等离子体改性TiO2/WO3/Bi2WO6纳米 复合材料及其可见光催化活性

以二水合钨酸钠和五水合硝酸铋为原料，通过优化水热法反应温度制备了WO3/Bi2WO6纳米片，将其与锐钛矿型TiO2纳米颗粒复合制备了可见光催化性能优良的TiO2/WO3/Bi2WO6复合光催化剂，并采用一种高密度管状等离子体放电装置对其进行表面改性。利用XRD、SEM、TEM、HRTEM、XPS、UV-Vis DRS、PL对样品进行了表征和分析，考察了其在可见光下降解亚甲基蓝的光催化性能。结果表明，当水热温度为120 ℃时，WO3/Bi2WO6纳米片具有较好的光催化性能；TiO2/WO3/Bi2WO6复合催化剂中掺入TiO2质量分数为10.7%时，所得三元复合材料的光催化性能远优于WO3/Bi2WO6纳米片；经等离子体改性处理后，三元复合材料的吸收边向可见光红移，放电输入功率的增加有助于提高复合材料的光催化活性，当放电电压为1.1 kV时，复合材料的降解速率常数分别是未处理样品和WO3/Bi2WO6的2.2倍和3.9倍。     

TiO2/SiO2/Fe3O4的光催化性能及动力学

采用溶胶－凝胶法在表面包覆了SiO2的磁基体Fe3O4上负载TiO2,制备了复合光催化剂TiO2/SiO2/Fe3O4。用AFM和XRD等对其进行了表征,并对其光催化降解溴氨酸的pH值、催化剂加入量、初始溶液浓度等条件进行了探讨。结果表明,当pH＝4.0、催化剂用量为2.0 g/L、初始溶液浓度为30 mg/L、光照时间为30 min时,溴氨酸脱色率可达96.2％,COD去除率为85.1％;动力学研究表明：在实验浓度范围内,溴氨酸的光催化降解反应符合一级动力学规律,反应速率常数（k）与初始溶液浓度（c0）的关系为lnk =－0.171lnc0－2.360;经过4次循环使用后,复合光催化剂仍能保持较高的光催化活性和较高的回收率。     

掺杂Co2O3对Na0．5Bi0.5TiO3基压电陶瓷性能的影响

通过固相法合成Na0.5Bi0.5TiO3+xmol%Co3+(简写为:NBT-xC)体系无铅压电陶瓷,并对其相结构、压电、介电及铁电性能进行了研究.XRD分析结果表明,所有组成均形成三方钙钛矿结构.SEM扫描电镜照片显示Co2O3的引入有利于晶粒长大,提高致密度.随着Co含量的增加,陶瓷的压电常数d33,机电耦合系数Kp都略有下降,机械品质因素Qm有明显提高,在x=3时达到极大值:0m-934,同时介电损耗出现极小值:tgδ=0.02(1kHz),综合得出Co离子起"硬性掺杂"作用.     

两种负载膜对纳米Fe~(3+)/TiO_2光催化活性的影响

用溶胶-凝胶法制得的纳米Fe3+/TiO2分别以玻璃和琼脂糖为负载体,采用浸渍-提拉法制备Fe3+/TiO2玻璃负载膜,水热合成法制得Fe3+/TiO2琼脂糖凝胶负载膜,通过降解某制药厂的制药废水,探讨两种负载膜对纳米Fe3+/TiO2光催化活性的影响及用琼脂糖为载体的可行性。结果表明,两种负载膜中纳米Fe3+/TiO2的晶相不变,但琼脂糖凝胶负载膜中纳米Fe3+/TiO2粒子的团聚较少,且不易脱落,重复使用性能高,光催化活性明显较Fe3+/TiO2玻璃负载膜强,从而显示了琼脂糖为载体的可行性、优越性和实用性。     

Copper reduced defective TiO2 nanoparticles with enhanced visible light photocatalytic activity

Defective TiO₂ attracted increasing attention due to its high photocatalytic activities. Herein, we report a facile and efficient method to fabricate gray defective TiO₂ by vacuum annealing raw TiO₂ materials with copper powders. The treated TiO₂ nanoparticles exhibit significantly enhanced visible‐light‐photocatalytic performance with photo‐degradation rate increased to 400% as that of pristine commercial P25 under visible light. The performance enhancements can be attributed to the disordered structure, optimized optical and electronic properties of defective TiO₂. In addition, this facile Cu reduction method provides an effective way to generate defective sites in other metal oxides for various potential applications.     

Study on the properties of nano‐TiO2 particles modified silk fibroin porous films

Using the freeze‐drying method, Nano‐TiO₂/silk fibroin porous films were synthesized with different ratios of TiO₂ to silk fibroin solution. Through scanning electron microscopy (SEM), X‐ray diffraction (XRD), thermogravimetric analysis (TGA), tensile strain, and water‐solubility tests, the structures and properties of these porous films were characterized. The SEM results indicated that the pores of the nano‐TiO₂/silk fibroin porous films were uniformly distributed by the freeze‐drying method. The XRD analysis indicated that the formation of nano‐TiO₂ particles might induce a conformational transition of silk fibroin from the typical Silk I to the typical Silk II structure partly with an increase in the crystallinity of the porous films. Compared with the pure silk fibroin porous films, the mechanical properties of nano‐TiO₂/silk fibroin porous films were improved, and its heat transition temperature was also enhanced; however, the water‐solubility of this material was diminished. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

微乳-水热法合成核壳型TiO2/Al2O3纳米粉体

本文采用微乳-水热法一步合成了核壳型TiO2/Al2O3纳米粉体.通过对产物的Zeta电位研究得出制备Ti(OH)4/Al(OH)3核壳前驱体的最佳pH值.并且采用XRD、TEM及SEM等表征方法与普通一步水热法合成的TiO2/Al2O3纳米粉体的晶形晶貌进行比较.结果表明:微乳-水热法能改善颗粒形状和大小,产品的颗粒大小均匀、平均晶粒粒径为13.68 nm.