Ag/AgCl/质子化g-C_3N_4纳米复合材料的制备及其光催化性能的研究

采用沉积-沉淀法制备Ag/AgCl/质子化g-C_3N_4(Ag/AgCl/p-g-C_3N_4)纳米复合材料,通过XRD、TEM、XPS、UV-Vis和PL对样品的结构、形貌和光学性能进行了表征。UV-Vis和PL分析表明,相比于纯gC_3N_4,p-g-C_3N_4和Ag/AgCl/p-g-C_3N_4纳米复合材料对可见光的响应能力和光生载流子的分离效率明显增强。通过可见光下降解甲基橙(MO)、盐酸四环素(TC)和环丙沙星(CIP)溶液评价样品的光催化性能。经优化后的Ag/AgCl/p-g-C_3N_4纳米复合材料在可见光照射60min后对MO的降解率达到90.4%,照射120 min后对TC和CIP的降解率分别为92.4%和76.1%。此外,Ag/AgCl/p-g-C_3N_4纳米复合材料具有良好的光催化稳定性。Ag/AgCl/p-g-C_3N_4纳米复合材料增强的光催化性能归因于Ag纳米颗粒的SPR效应以及Ag、AgCl和p-gC_3N_4之间的协同效应。     

盘状α-Fe2O3/Ag/AgCl复合纳米颗粒的可控制备及LSPR增强光催化应用

采用多步合成方法制备了一种盘状 三元α-Fe2O3/Ag/AgCl复合纳米颗粒。首先,通过Al3+辅助的水热合成方法得到盘状α-Fe2O3纳米颗粒;然后,采用经典的银镜反应,将Ag纳米颗粒负载于盘状α-Fe2O3纳米颗粒表面;最后,原位氧化Ag纳米颗粒即得α-Fe2O3/Ag/AgCl复合纳米颗粒。采用XRD、SEM、TEM和紫外-可见吸收光谱等对α-Fe2O3/Ag/AgCl复合纳米颗粒的形貌、结构和光催化性能进行表征,并将该光催化剂在模拟太阳光照射下对罗丹明B、酸橙7和孔雀绿等有机染料进行降解。试验结果表明,相比于商业化的TiO2（P25）,α-Fe2O3/Ag/AgCl表现出更好的光催化活性。光催化性能的提高,主要是由于窄/宽禁带半导体与贵金属Ag复合,使电荷能够在贵金属Ag、半导体α-Fe2O3、AgCl之间进行有效转移。这种复合纳米颗粒为合成性能优异的等离子体光催化剂提供了良好的借鉴,并为其在环境治理的实际应用中提供了良好的范例。     

离子液辅助水热法合成树枝状硫化镉及光催化性能

采用氯化镉和硫脲为原料,在乙二胺氟硼酸盐离子液水溶液中水热法合成了树枝状硫化镉,所得产物经X射线衍射﹑扫描电镜﹑荧光光谱技术进行表征,并对枝状硫化镉光催化降解甲基橙的能力进行测试。结果表明,离子液和反应时间在枝状结构的形成中起重要作用,探讨了其形成机理。光催化性能的测试结果表明,枝状硫化镉在紫外光的照射下对甲基橙具有较高的光催化降解率,经过280min,甲基橙的降解率可以达到85%。     

提拉法制备自清洁型Ag/AgCl/GO表面增强拉曼基底

采用化学还原法制备Ag溶胶,采用水热法制备AgCl溶胶,利用提拉法在石英基片上通过交替提拉氧化石墨烯(GO)、Ag溶胶、AgCl溶胶,制备出了Ag/AgCl/GO复合薄膜并可用作表面增强拉曼基底。采用SEM,XRD,UVVis以及激光拉曼光谱测试仪对复合薄膜的成分、结构及性能进行表征。结果表明,通过提拉法成功地制备出了Ag/AgCl/GO复合薄膜,Ag/AgCl/GO复合薄膜具有较强的表面增强拉曼散射(SERS)性能和可见光光催化性能;AgCl的引入使得Ag/AgCl/GO复合薄膜具有自清洁性能,自清洁性能使得基底可以重复利用。     

Ag/TiO2纳米粒子的制备及其光催化降解苯酚的性能研究

采用溶胶-凝胶法制备了TiO₂和Ag/TiO₂纳米粒子,采用涂覆法制备了TiO₂和Ag/TiO₂纳米粒子光催化剂基板样品。使用XRD、SEM和拉曼光谱等手段,对TiO₂和Ag/TiO₂纳米粒子进行了晶格结构和表面形貌研究;通过UV-Vis,研究了TiO₂和Ag/TiO₂纳米粒子光催化剂基板样品在光催化反应器中对苯酚的光催化降解性能。结果表明,制备的TiO₂和Ag/TiO₂纳米粒子均为纯净的金红石相,二者表面形貌并没有明显区别,Ag单质粒子成功负载在TiO₂纳米材料上;Ag单质粒子的负载,明显增强了TiO₂纳米粒子对可见光的吸收,且Ag/TiO₂纳米粒子薄膜对苯酚的光催化降解性能明显优于TiO₂纳米粒子薄膜;在光催化降解1 h后,TiO₂纳米粒子薄膜仅催化降解了溶液中30%(质量分数)的苯酚,且光催化降解出现了饱和趋势,而Ag/TiO₂纳米粒子薄膜可催化降解溶液中50%(质量分数)的苯酚,且在光催化降解3 h后,仍未出现饱和趋势。     

Ag/AgCl/MoO_3复合材料的制备及其光催化性能

利用水热合成法合成六方相晶体结构的MoO3微晶,采用沉淀-沉积法和光致还原法将Ag/AgCl纳米颗粒沉积于MoO3微晶上,从而制得新型的Ag/AgCl/MoO3异质结光催化剂。通过包括紫外-可见漫反射吸收光谱(UV-Vis-DRS)等方法在内的各种测试技术对催化剂结构、形貌等进行表征。并以苯并噻吩(BT)为目标硫化物,研究在可见光下催化剂用量、氧化剂用量、前驱体浓度及反应时间对BT的氧化脱除的影响。研究结果表明:Ag/AgCl/MoO3异质结在催化剂用量为1.5g/L,氧化剂用量O∶S=4,前驱体Mo(VI)浓度为0.07mol/L,可见光照射2.5h后,光催化氧化脱硫活性达92%。     

离子液体中不同形貌硫化镉的合成及光催化活性

以硝酸镉和硫代乙酰胺为原料,在不同的离子液体水溶液中采用超声法合成了不同形貌的硫化镉。采用XRD、SEM、BET、紫外-可见吸收光谱等手段对样品的结构和光学性能进行了考察,以罗丹明B为目标降解物考察了不同形貌硫化镉的光催化性能。结果表明,在不同的离子液体水溶液中可分别得到粒状、棒状和粒棒混合体。对比了纳米粒子、纳米棒和粒棒混合体对罗丹明B的降解率,结果表明,CdS纳米粒子具有更高的光催化效率,其粒状硫化镉比表面积为79.5m2/g,远大于其它形状的硫化镉。在紫外光和可见光的照射下,反应120min罗丹明B的降解率分别为97%和30%。离子液体的特殊结构是粒状硫化镉具有较高光催化活性的原因。     

Ag掺杂APS改性的TiO2颗粒的制备及其光催化降解作用

为提高Ag/TiO2纳米颗粒的光催化降解作用,采用聚合凝胶工艺路线,以钛酸四丁酯为前驱体,硝酸银为银源,通过向反应体系引入鳌合剂醋酸、表面改性剂γ-氨丙基三乙氧基硅烷(APS)以及还原剂甲醛等添加剂,制备出TiO2粉体及Ag/TiO2纳米复合粉体。利用FT-IR、XRD、TG-DTA、TEM和UV-Vis-NIR等手段对样品进行表征。结果表明,经γ-氨丙基三乙氧基硅烷改性的TiO2颗粒掺Ag后分散性得到改善,粒径约1 nm的Ag颗粒较均匀地分布在10～15 nm TiO2颗粒上;可见光的利用和锐钛矿热稳定性都得到提高;Ag/TiO2纳米颗粒在光照下对甲基橙具有良好的光催化降解效果。     

g-C_3N_4/Ag/AgCl/TiO_2复合材料的制备及其光催化性能研究

采用经硫酸处理过的三聚氰胺热解制备g-C_3N_4,利用光照还原在其表面负载Ag颗粒,再通过原位沉积法沉积上AgCl和TiO_2,制得g-C_3N_4/Ag/AgCl/TiO_2复合催化剂。既而采用XRD、TEM、FT-IR、UV-Vis-DRS和PL等分析手段对材料进行表征。并用10mg催化剂、50mL 15mg/L甲基橙溶液作为反应体系进行光催化实验。光照80min后,g-C_3N_4/Ag/AgCl/TiO_2光催化剂对甲基橙的降解率为99.35%。相同条件下,g-C_3N_4、g-C_3N_4/Ag和g-C_3N_4/TiO_2催化剂对甲基橙的降解率分别为34.29%、45.33%和55.84%。该结果表明,复合材料g-C_3N_4/Ag/AgCl/TiO_2具有优异的光催化性能。优异的光催化性能得益于材料中g-C_3N_4、Ag、AgCl和TiO_24种组分间的协同作用。     

四方排列有序Ag/TiO2空心微球的制备及光催化性能

采用低温垂直沉积法制备了聚苯乙烯(PS)胶体模板,由于低温下粒子热运动受到抑制,排列时发生位错,因此模板中存在大面积四方排列结构。然后采用化学镀法、溶胶-凝胶法在PS微球表面依次沉积银纳米粒子、纳米TiO2,最后高温煅烧除去模板制备了四方排列有序Ag/TiO2空心微球。通过扫描电镜(SEM)、X射线衍射(XRD)对样品进行表征。结果表明这种材料很好地保持了模板的四方排列,具有高度有序的纳米结构。选择降解甲基橙溶液来检验样品的光催化性能,并与纳米TiO2薄膜、四方排列TiO2空心微球的光催化性能进行比较,结果表明四方排列Ag/TiO2空心微球具有最佳的光催化性能。这是有序空心纳米结构和银纳米粒子的沉积共同作用的结果。     

Environmentally benign chitosan as reductant and supporter for synthesis of Ag/AgCl/chitosan composites by one-step and their photocatalytic degradation performance under visible-light irradiation

A novel Ag/AgCl/chitosan composite photocatalyst was successfully prepared by a simple one-step method. During this progress, environmentally benign chitosan not only served as reductant to reduce Ag⁺ to Ag⁰ species, but also acted as supporter for Ag/AgCl nanoparticles. XRD, SEM, EDX, UV-vis DRS and XPS were employed to characterize the as-prepared simples. SEM images of Ag/AgCl/chitosan composites revealed that Ag/AgCl nanoparticles were successfully loaded onto chitosan without obvious aggregation. All Ag/AgCl/chitosan composites exhibited efficient photocatalytic activity for the degradation of rhodamine B (RhB) under visible-light irradiation. The result of photocatalytic degradation experiment indicated that 20% of the mass ratio of AgCl to chitosan was the optimum, and after 40 min photocatalytic reaction, the degradation rate reached about 96%.     

Growth of Silver Nanowires from Controlled Silver Chloride Seeds and Their Application for Fluorescence Enhancement Based on Localized Surface Plasmon Resonance

A “Polyol” method has granted low‐cost and facile process‐controllability for silver‐nanowire (Ag‐NW) synthesis. Although homogenous and heterogeneous nucleation and growth during Ag‐NW synthesis are possible using polyol methods, heterogeneous nucleation and growth of Ag NW guarantees highly selective growth of nanostructures using silver chloride (AgCl) seeds, which provides a stable source of chloride ions (Cl?) and thermodynamic reversibility. In this paper, a microdroplet has been adopted to synthesize uniform AgCl seeds with different diameter that are used for seed‐mediated Ag‐NW synthesis. The concentration of two precursors (AgNO₃ and NaCl) in the droplets is modulated to produce different sizes of AgCl seeds, which determines the diameter and length of Ag NWs. The process of the seed‐mediated growth of Ag NWs has been monitored by observing the peak shift in the time‐resolved UV–vis extinction spectrum. Furthermore, the distinct plasmonic property of Ag NWs for transverse and longitudinal localized‐surface‐plasmon‐resonance (LSPR)‐mediated fluorescence enhancement is utilized. The high aspect ratio and sharp tips work as simple antennas that induce the enhanced fluorescence emission intensity of a fluorophore, which can be applied in the fields of biological tissue imaging and therapy.     

Hierarchical silver nanodendrites: One-step preparation and application for SERS

Without using any other reducing reagents or templates, a one-step approach for synthesizing dendritic Ag nanostructure by the treatment of sliver ions only in the presence of silk fibroin biomacromolecule is described. The morphology and structure of as-prepared silver nanodendrite are characterized, and its application for surface-enhanced Raman scattering (SERS) is also investigated. It has been found that the morphology of as-prepared Ag dendrite is dependent on the reaction duration, but not the concentration of sliver ions in the reaction process. SERS study shows that the silver nanodendrites give an intensive and enhanced Raman scattering when pyridine is used as a probing molecule. It is suggested that silk fibroin provides dual reductant and structure-directing roles to promote sliver ions forming shape-controlled nanostructures in high yield.     

Solvothermal fabrication of uniform silver nanowires

Conventional polyol synthesis has been widely used for the preparation of silver nanostructures with different morphologies. However, there is a drawback that it is difficult to control the reaction parameters for shape-controlled synthesis of silver nanostructures, such as the rate of the addition of silver ions to the solution. In this paper, we combine polyol process and solvothermal method for easily synthesizing silver nanostructures. Importantly, the introduction of cuprous chloride (CuCl) to the reaction leads to increasing the population of twinned Ag seeds (required for wire growth) at the expense of that of single Ag seeds. Silver nanowires (Ag NWs) with uniform width (~80?nm in width) can be obtained in the presence of poly(vinyl pyrrolidone) (PVP). Some other parameters, such as the reaction temperature and molar ratios of the repeating unit of PVP to AgNO₃ (R), also have been discussed. A possible mechanism is put forward to understand the evolution of silver nanostructures.     

A wet chemistry method for the construction of silver nanosandwichs using laponite clays

Herein, we report a method for the construction of new silver nanostructures in aqueous solution with potential applications as nanocapacitors. A synthetic clay composed of disk-shaped particles of approximately 30 nm in diameter and 1 nm thickness, called laponite, was treated with activated Ag solution and allowed to react overnight to form silver nanodisks on each face of the clay in a sandwich assembly. The products of this reaction were analyzed by Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM), and X-ray Photoelectron Spectroscopy.     

Nanoparticles of silver powder obtained by mechano-chemical process

The silver (Ag) powder was synthesised in a mechano-chemical (MC) process by inducing a solid-state displacement reaction between silver chloride (AgCl) and copper (Cu). The AgCl and Cu were ground in atmosphere conditions using a planetary ball mill. The reaction caused the mixture of AgCl and Cu to change the composition of the mixture, such as Ag and copper chloride (CuCl). CuCl was separated from MC product by leaching with ammonium hydroxide and we obtained Ag powder as the final product. Moreover, ascorbic acid (C₆H₈O₆) was used as the additive to improve dispersion of Ag powder during MC process. The ground powders, formed in the presence of additive, were characterised by X-ray diffraction (XRD) and scanning electron microscope (SEM). The XRD determined that the reaction between AgCl and Cu was complete in almost all the experiments carried out. SEM examinations revealed that the size of the particles in the synthesised metallic Ag powder was in the range of 30–300 nm.     

Ag/AgCl固体参比电极性能研究

研究了浸泡时间、粉末制备方法和相对流速等因素对专利方法制备的全固态Ag/AgCl参比电极的电位稳定性影响.实验发现,固相法粉末制备的电极其浸泡稳定性好,电位波动在2mV以内,海水流速小于3.6 m·s-1时对电极电位无显著影响,满足工程需要,可作为水下阴极保护电位检测和监测用参比电极.     

Morphology-controlled synthesis of silver nanostructures via a solvothermal method

Silver nanostructures have been synthesized by a simple solvothermal method in the presence of poly(vinylpyrrolidone) (PVP). Typically, different exotic agents (NaOH, KBr, NaCl) are added into the reaction system. The anions (OH⁻, Cl⁻, Br⁻) from these agents can combine Ag⁺ to form silver salt colloids (AgOH, AgBr and AgCl), decreasing the concentration of free Ag⁺ in the initial formation of silver seeds. However, different release rates of Ag⁺ from these colloids to the solution in the subsequent reaction may play different roles in the growth of silver seeds. The as-prepared silver nanostructures were characterized by UV–vis absorption spectrum, X-ray diffraction (XRD) and field emission scanning electron microscope (FSEM). It is found that silver nanostructures with various shapes can be obtained by the addition of different exotic agents. Finally, our work provides a simple route to synthesize silver nanostructures with controllable morphologies.     

Synthesis and characterization of AgO nanostructures by precipitation method and its photocatalyst application

In this research, a precipitation method was used in order to synthesize AgO nanostructures with the aid of silver nitrate as the starting reagent in an aqueous solution. To examine the effect of different surfactants such as glucose, sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, and cetyltrimethylammonium bromide on the morphology and particle size of final products several tests were performed. The structural, morphological, and optical properties of as-obtained products were characterized by techniques such as Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and ultraviolet–visible spectroscopy. Furthermore, the hysteresis loop measured at room temperature shows a ferromagnetic behavior of the AgO nanostructures. To evaluate the catalytic properties of nanocrystalline silver oxide (AgO), the photocatalytic degradation of rhodamine-B under visible light irradiation was carried out.     

Large-scale synthesis of silver nanowires via a solvothermal method

Silver nanostructures have been synthesized through a simple solvothermal method by reducing silver nitrate (AgNO₃) with ethylene glycol (EG) and using poly(vinylpyrrolidone) (PVP) as an adsorption agent. Different concentrations of ferric chloride (FeCl₃) are added into the solution. It is found that AgCl colloids formed in the initial stage greatly influence the final morphologies of the products. When a low-concentration FeCl₃ solution is used, there is a mixture of silver nanoparticles and nanowires. However, when a high-concentration FeCl₃ solution (100 μM) is used, large amounts of AgCl colloids appear, resulting in decreasing free Ag⁺ during initial formation of silver seeds and slowly releasing of Ag⁺ to the solution in the subsequent reaction. This leads to the formation of silver nanowires. Furthermore, an increase in the concentration of FeCl₃ from 100 to 300 μM results in the synthesis of silver nanowires with larger sizes. In addition, Fe(III) is reduced to Fe(II) form which in turn reacts with and removes adsorbed atomic oxygen from the surface of silver seeds. In this case, uniform silver nanowires can be obtained.