纳米结构锌及锌氧化物薄膜对甲基橙的降解作用研

采用磁控溅射方法制备了纳米金属锌薄膜,结合后续的空气退火处理制备了纳米锌氧化物薄膜. 金属锌薄膜对甲基橙的还原降解以及锌氧化物薄膜对甲基橙的光催化降解过程都可以用一级反应动力学方程来描述. 甲基橙溶液在金属锌膜的还原降解下具有最快的褪色速率,但矿化不完全：在紫外光波段出现的额外吸收峰表明生成了芳香族中间产物. 完全氧化的氧化锌薄膜对甲基橙的光催化降解速率仅为金属锌膜还原降解速率的1/4左右,没有出现芳香族中间产物. 另外实验发现部分氧化的锌氧化物薄膜对甲基橙的光催化降解速率明显高于完全氧化的氧化锌薄膜,光催化活性的提高可能由于部分氧化薄膜中同时存在的金属锌及氧化锌相之间的协同效应.     

TiO2/SnO2复合光催化剂的制备及性能

采用特殊液相沉淀法制备纳米级的TiO2/SnO2复合粒子,对制备的纳米TiO2/SnO2采用XRD、TEM等手段进行了表征。用它做催化剂在日光下对甲基橙溶液进行了光催化实验。结果表明,纳米级TiO2/SnO2复合催化剂比纯TiO2的催化活性好,当SnO2摩尔百分数为20%时效果最佳,在60min内对10mg/L的甲基橙水溶液的降解率高达90.2%,具有较好的光催化活性。     

溶胶-凝胶法制备纳米氧化锌及其光催化性能

采用溶胶-凝胶法制备ZnO纳米粒子,采用X-射线衍射仪(XRD)、透射电镜(TEM)等手段对样品进行了表征;以纳米氧化锌作为光催化剂,利用300W高压汞灯为光源对甲基橙溶液进行光催化实验。实验结果表明:以汞灯为光源,纳米ZnO为催化剂对甲基橙溶液进行光催化时,纳米ZnO的最佳投加量为0.1020g。     

磁性纳米TiO_2/Fe_3O_4的制备及其光催化性能

采用特殊液相沉淀法分两步制备了壳核结构的磁性纳米TiO2/Fe3O4,并讨论了TiO2/Fe3O4比例对其磁性的影响。利用XRD、TEM和VSM对其进行了表征,用它做催化剂,甲基橙溶液为降解目标,在日光作用下对其光催化活性进行了研究,并测出了其回收率。结果表明,在本实验条件下制备的磁性纳米TiO2/Fe3O4表现为超顺磁性,具有较强的光催化活性和较高的回收率。当TiO2∶Fe3O4为4∶1,在450℃焙烧30min条件下得到的催化剂,对20mg/L的甲基橙溶液在60min内降解率高达91.5%,明显高于纯TiO2的催化活性,在外加强磁场的作用下,此催化剂很快从溶液中分离出来,测得其回收率为88.2%。     

CdTe量子点/膨润土复合材料的制备及其光催化降解甲基橙

以CdCl2和Na2TeO3为反应物,抗坏血酸为还原剂,通过湿化学法合成CdTe量子点/膨润土复合材料.采用X射线衍射、荧光光谱及紫外-可见光谱等分析技术对其结构及光学性能进行表征.以汞灯为光源,甲基橙为目标污染物,研究了CdTe/膨润土复合材料的光催化活性.实验表明:在甲基橙溶液初始浓度为10 mg/L时,经汞灯光照反应60 min后,CdTe/膨润土因光催化反应对甲基橙的降解率为66.23％,优于CdTe量子点光催化剂.     

强悬浮性纳米TiO2的制备、表征及光催化活性研究Ⅱ.光催化活性研究

将甲基橙溶液作为模拟废水,在紫外灯照射下,通过测量甲基橙溶液在470nm处吸光度的变化,考察了热分解制备纳米TiO2后处理过程中采用硅油淬火改性和自然冷却所得产物的光催化活性,并初步分析了两者光催化甲基橙的机理和在35min内的降解率和动力学反应过程。结果表明：两者均具有良好的光催化降解效果,且活性差别不大。但经硅油淬火改性的纳米TiO2因在水中具有强悬浮性,可更为有效地利用外部光源在工业废水的表层降解有害成分。     

硫和银共掺杂介孔TiO2的制备、表征及其对染料的光催化降解活性

以P123为模板,以钛酸四正丁酯、硝酸银和硫脲为原料采用模板法制备了一系列硫和银共掺杂介孔TiO₂光催化材料．利用SEM、XRD、BET和紫外-可见光谱等技术对其形貌、晶体结构及表面结构、光吸收特性等进行了表征．以甲基橙溶液的光催化降解为模型反应,考察了不同掺杂量的样品在紫外和可见光下的光催化性能．结果表明,用模板法制备的共掺杂介孔TiO₂光催化材料在紫外和可见光条件下较纯介孔TiO₂和单掺杂介孔TiO₂对甲基橙溶液具有更好的光催化降解效果, 且硫和银的掺杂量及样品焙烧温度显著影响该材料的催化性能．当硫掺杂量为2mol%和银掺杂量为1mol%,在500 oC 焙烧2 h所得光催化材料的催化性能最佳,4 h即可使甲基橙的降解率达98.8%,重复使用4次仍可使甲基橙的降解率保持在87.5%以上     

铁和镧共掺杂纳米二氧化钛光催化剂的制备、表征及其光催化活性

以葡聚糖为模板,钛酸四正丁酯、硝酸铁和硝酸镧为前驱体采用模板法制备了一系列铁、镧单掺杂及共掺杂纳米TiO₂光催化剂. 利用SEM、XRD、BET比表面积测定和UV-Vis等技术对其形貌、晶体结构及表面结构、光吸收特性等进行了表征. 以甲基橙溶液的光催化降解为模型反应,考察了不同掺杂的样品在紫外和可见光下的光催化性能. TiO₂材料具有较大的比表面积(约150 m²/g),铁和镧共掺杂纳米TiO₂在可见光区域有较强的吸收,在紫外和可见光条件下较纯TiO₂和单掺杂TiO₂对甲基橙溶液具有更好的光催化降解效果,且铁和镧的掺杂量显著影响该材料的催化性能. 当铁掺杂量为0.5mol%、镧掺杂量为0.3mol%,在500 ℃焙烧2 h所得光催化材料的催化性能最佳,焙烧4 h即可使甲基橙的降解率达98.8%,且该复合材料有较高的循环回收利用率,重复使用4次仍可使甲基橙的降解率保持在88%以上.     

金属离子对纳米TiO2悬浊液的光催化性能影响的光谱研究

以钛氧有机物为前驱体,利用微乳液法制备了纳米TiO2微晶。用X射线衍射(XRD)和红外光谱(FTIR)等测试技术对产物进行了表征,并就纳米TiO2悬浊液中加入金属离子后光催化降解甲基橙溶液进行了初步的研究。光谱分析表明,纳米TiO2悬浊液中加入Bi3 离子后对甲基橙溶液的光催化降解有很大的促进作用,Bi3 与TiO2质量比为1∶8及TiO2的浓度为1.6g·L-1时光催化活性最佳。     

BaSnO3纳米粒子的制备及对亚甲基蓝的光催化性能

以结晶四氯化锡(SnCl4·5H2O)和乙酸钡[Ba(CH3COO)2]为原料,以有机碱四甲基氢氧化铵N (CH3)4OH为矿化剂,采用共沉淀法制备BaSnO3光催化剂,并研究了其对亚甲基蓝溶液的光催化性能.结果表明:在可见光照射下,BaSnO3光催化剂对亚甲基蓝溶液有明显的光催化降解作用.当催化剂浓度为40mg/L,反应时间为100min时,降解率可达93％以上.     

Effect of Particle Size and Phase Composition of Titanium Dioxide Nanoparticles on the Photocatalytic Properties

Titanium dioxide (TiO₂) nanoparticles were prepared by the oxidation of titanium tetrachloride (TiCl₄) in a diffusion flame reactor. The average diameter of particles was 15–30 nm and mass fraction of anatase ranged from 40% to 80%. Effects of particle size and phase composition of those TiO₂ nanoparticles on photocatalytic properties such as decomposition of methylene blue, bacteria and ammonia gas were investigated. The degree of decomposition of methylene blue by the TiO₂ nanoparticles under the illumination of the black light was directly proportional to the anatase mass fraction, but inversely to the particle size. The decomposition of bacteria and ammonia gas by the TiO₂ nanoparticles under the illumination of the fluorescent light showed the same trend as in the case of the methylene blue.     

SrSnO3纳米粒子的制备及其光催化性能

以硝酸锶[Sr（NO₃）₂]和结晶四氯化锡（SnCI₄·5H₂O）为原料,有机碱四甲基氢氧化铵[N（CH₃）₄OH]为矿化剂,采用共沉淀法制备SrSnO₃纳米粒子。用XRD和IR对样品的物相和结构进行表征,并研究了对亚甲基蓝废水的光催化降解性能。结果表明:用该法在500℃煅烧1h时制备的纯立方相SrSnO₃纳米晶粒在可见光照下具有良好的光催化性能。催化剂浓度为60mg/L,反应时间为100min时,降解率可达94%。     

铂颗粒粒径效应:负载铂纳米颗粒的TiO2薄膜性质研究

制备了负载不同大小Pt纳米颗粒的TiO薄膜。利用TEM测定了Pt粒子的大小,XRD,UV—Vis和测量光电流等方法对TiO2复合膜进行了表征,以亚甲基蓝降解反应评价了Pt／TiO2薄膜的光催化活性。结果表明,在负载相同物质的量的Pt情况下,Pt颗粒的大小直接影响TiO2薄膜的性能,显示较强的粒径效应,当负载平均粒径约5nm的Pt粒子后,薄膜具有最高的光电流和光催化活性。     

Synthesis of ZnO nanoparticles using surfactant free in-air and microwave method

Zinc oxide nanoparticles have been successfully prepared by a facile route involving the reaction of zinc sulphate heptahydrate and sodium hydroxide through drop-by-drop mixing synthesis-IA, instant mixing synthesis-IA and under the influence of microwave radiations. The synthesis under different reaction conditions played an important role and led to the formation of zinc oxide nanoparticles of different size and shapes. The synthesized nanoparticles were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques. The concentration dependent antimicrobial activity of synthesized ZnO nanoparticles was carried out. The photocatalytic activity was evaluated using the photodegradation of methylene blue (MB) dye under UV irradiation. Further, the optical properties of as-prepared ZnO nanoparticles were investigated by UV-vis spectrophotometry. The absence of surfactant led to a simple, cheap and fast method of synthesis of zinc oxide nanoparticles.     

Visible-light photocatalytic degradation of methylene blue with laser-induced Ag/ZnO nanoparticles

The preparation of Ag doped ZnO nanoparticles conducted through the method of laser-induction is presented in this work. The Ag/ZnO nanoparticles attained from various weight percentages of added AgNO₃ relative to ZnO were applied under visible-light irradiation for evaluating the heterogeneous photocatalytic degradations of methylene blue (MB) solutions. It was shown that the catalytic behavior of Ag/ZnO nanoparticles in the visible-light range is notably improved through the Ag deposition onto ZnO nanoparticles by the method of laser-induction with a maximum effectiveness of 92% degradation. The properties of the nanoparticles were characterized by the employments of UV-vis spectroscopy (UV-vis), X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), and selected-area electron diffraction (SAED).     

Study on highly visible light active Bi-doped TiO2 composite hollow sphere

Bi-doped hollow titania spheres were prepared using carbon spheres as template and Bi-doped titania nanoparticles as building blocks. The Bi-doped titania nanoparticles were synthesized at low temperature. The prepared hollow spheres were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), UV-vis diffuse reflectance spectrum (DRS) and X-ray photoelectron spectroscopy (XPS). The effects of Bi content on the physical structure and photocatalytic activity of doped hollow titania sphere samples were investigated. Results showed that there was an optimal Bi-doped content (4%) for the photocatalytic degradation of methylene blue (MB).     

Synthesis of anatase titania-carbon nanotubes nanocomposites with enhanced photocatalytic activity through a nanocoating-hydrothermal process

Anatase TiO₂ nanoparticles were covalently anchored onto acid-treated multi-walled carbon nanotubes (MWNTs) through a nanocoating-hydrothermal process to obtain TiO₂-MWNTs nanocomposites. The composition and structural properties of the nanocomposites were characterized by XRD, BET, TG, TEM, HRTEM, EDX, XPS, and FTIR, and the formation of ester-bond linkage between TiO₂ nanoparticles and MWNTs was demonstrated. The enhanced photocatalytic activity of TiO₂-MWNTs nanocomposites was probed by photodegradation reaction of methylene blue under visible-light irradiation.     

One single-step synthesis of multifunctional methylene blue-coated magnetite nanoparticles

This work reports the preparation of hybrid nanoparticles with magnetic and fluorescent properties. The material is based on magnetite nanoparticles (NPs) coated with fluorophore methylene blue (MB). The synthesis of a multifunctional material with magnetic and fluorescent features is carried out in a single step by electrooxidation. The effect of the presence of methylene blue in the synthetic medium is discussed. The presence of MB polymer at the NP surface is demonstrated with visible UV, infrared and Raman spectroscopy. The NPs morphology, structure and size are determined by transmission electron microscopy (TEM) and X-ray diffraction. The magnetic properties are measured with a vibrating sample magnetometer (VMS). In overall, the results show that magnetite NPs generated electrochemically in the presence of MB present a core/shell structure, being the NP at the core surrounded by methylene blue polymer, leading to a nanocomposite or hybrid material.     

Sonochemical synthesis, photocatalytic activity and optical properties of silica coated ZnO nanoparticles

In this paper, we report the synthesis of silica coated ZnO nanoparticles by ultrasound irradiation of a mixture of dispersion of ZnO, tetraethoxysilane (TEOS), and ammonia in an ethanol-water solution medium. The silica coating layer formed at the initial TEOS/ZnO loading of 0.8 for 60 min ultrasonic irradiation was uniform and extended up to 3 nm from the ZnO surface as revealed from HR-TEM images. Silica coated ZnO nanoparticles demonstrated a significant inhibition of photocatalytic activity against photodegradation of methylene blue dye in aqueous solution. The effects of silica coating on the UV blocking property of ZnO nanoparticles were also studied.     

Effects of NiTiO3 nanoparticles supported by mesoporous MCM-41 on photoreduction of methylene blue under UV and visible light irradiation

In this work, we report the synthesis of nickel titanate nanoparticles loaded on nanomesoporous MCM-41 nanoparticles to determine the effect of MCM-41 nanoparticles on the photocatalytic activities of nickel titanate (NiTiO₃) nanoparticles by using simple solid-state dispersion (SSD) method. Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and UV–Vis diffuse reflectance spectra (DRS) analysis were used to characterize the size and morphology of the obtained nanocomposite. The photocatalytic activity (PA) of the as-prepared NiTiO₃ loaded on MCM-41 was evaluated by degradation of the methylene blue under irradiation of UV and visible light. The results showed that NiTiO₃ loaded on nanosize MCM-41 has higher photocatalytic activity than that of NiTiO₃ nanoparticles.