Preparation and characterization of AgSt/AgCl composite grains

AgSt/AgCl composite grains were prepared by adding chloride ions to a mixed solvent in which silver stearate (AgSt) grains were dispersed under the condition of controlled pH value and characterized by SEM,XRD,UV and DSC.The results showed that AgSt/AgCl composite grains were composed of plate-like AgSt grains with small face-centered cubic AgCl particles formed on the surface of AgSt.UV spectra displayed a red shift of absorption for AgSt/AgCl relative to pure AgSt or AgCl.DSC showed a new thermal phase transition of AgSt/AgCl grains.     

AgSt/AgBr复合物的制备及其热行为研究

分别以溴化钠(NaBr)为溴源、硬脂酸银(AgSt)为底物,用原位法合成了复合物AgSt/AgBr.利用红外光谱(FTIR)、扫描电子显微镜(SEM)、X射线衍射(XRD)与热重-差示扫描量热(TG-DSC)技术对复合物的结构、尺寸、形貌、晶型以及热行为进行了表征.结果表明,1)复合物由底物AgSt与尺寸为30—50nm的外延立方体AgBr粒子构成;2)AgSt/AgBr复合物在较低的温度下出现两个新的吸热相变峰,分别对应于97.8℃和108.8℃;3)AgSt/AgBr复合物的起始分解温度较AgSt也有所降低.     

新型2-巯基苯并咪唑银/硬脂酸银(AgMBM/AgSt)的制备、表征及其在PTG材料中的成像性能研究

分别以硬脂酸银(AgSt)为本体、2-巯基苯并咪唑(MBM)为修饰剂,合成了一种新型的2-巯基苯并咪唑银/硬脂酸银(AgMBM/AgSt)复合结构颗粒.利用红外光谱仪(FTIR)、透射电子显微镜(TEM)、X射线衍射仪(XRD)以及热重-差示扫描量热仪(TG-DSC)对复合颗粒的微观结构、形貌、晶型以及热相变行为进行了表征,研究了AgMBM/AgSt作为光敏热成像(PTG)材料银源时的成像性能.结果表明,AgMBM/AgSt由本体AgSt以及其表面负载的AgMBM小颗粒构成.与本体AgSt相比,AgMBM/AgSt在80℃附近出现新的热相变峰,其热分解温度也有所降低.当AgMBM/AgSt为银源时,PTG材料的热显影密度显著增加,而灰雾仍然保持较低水平.     

Characterization and photocatalytic properties of silver and silver chloride doped TiO2 hollow nanoparticles

Using polystyrene（PSt） particles as template,PSt/TiO₂ composite particles with AgCl incorporation were prepared through hydrolysis of tetrabutyl titanate in the presence of AgNO₃ and NaCl.AgCl doped TiO₂ hollow particles were successfully prepared with the PSt/TiO₂ composite microspheres pretreated at 180℃followed by calcination.The morphology of PSt/TiO₂ particles and the crystal structures of the AgCl doped TiO₂ hollow particles were characterized.The photocatalytic activity of the doped TiO₂ hollow particles in degradation of Rhodamine B was tested under UV and visible lights and compared to that with Ag doped TiO₂ particles.The results showed that TiO₂ hollow particles,either doped with Ag or AgCl,demonstrated higher photocatalytic activity than the pure TiO₂ particles.This enhancement in photocatalytic activity was more significant with AgCl doped TiO₂ than that with Ag doped,and more distinct when the degradation was done under visible light than that under LTV light.     

硬脂酸钡对光敏热成像材料感光性能的影响

研究了硬脂酸钡(简称BaSt2)对光敏热成像材料(PTG材料)感光性能的影响,结果表明,AgBr/AgTTA摩尔比为1∶4时,PTG材料感光度最大,加入BaSt2后可将感光度提高4倍左右,而灰雾增加很小。本文通过对AgBr乳剂的光吸收和BaSt2的DSC研究,初步分析了BaSt2影响PTG材料感光性能的可能原因。     

立方体氯化银/溴碘化银外延乳剂的离子电导

利用微机控制平衡双注法在不同pAg条件下,成功地制备了三种单分散十四面体AgBr(Ⅰ)主晶并随后在其(111)面上外延淀积AgCl而获得三种单分散AgCl,AgBr(Ⅰ)外延立方颗粒乳剂,外延颗粒介电频谱曲线出现明显分立的双峰,分别相应于其中AgBr(Ⅰ)和AgCl两相对离子电导的贡献,主晶及外延颗粒的离子电导均随制备时的pAg变化,但变化规律不同。     

Synthesis of cubic Ag@AgCl and Ag@AgBr plasmonic photocatalysts and comparison of their photocatalytic activity for degradation of methyl orange and 2,4-dichlorophenol

Uniform cubic Ag@AgCl and Ag@AgBr plasmonic photocatalysts with side length of 0.7 µm were synthesized by a facile green route, in which a controllable double-jet precipitation technique was employed to fabricate homogeneous cubic AgCl and AgBr grains while a photoreduction process was used to produce Ag nanoparticles (NPs) on the surface of AgCl and AgBr grains. The synthesized samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis, X-ray photoelectron spectroscopy (XPS), and ultraviolet–visible (UV–Vis) diffuse reflectance spectroscopy (DRS). The photocatalytic activities of Ag@AgCl and Ag@AgBr were compared using degradation of methyl orange (MO) dye and 2,4-dichlorophenol (2,4-DCP) under visible-light irradiation. Ag@AgBr showed higher photocatalytic activity for MO degradation but weaker activity for 2,4-DCP decomposition. Possible degradation mechanisms are proposed to interpret these contrary paradoxical experimental results.     

异质结构AgCl/Bi2WO6微米球制备、表征及其光催化性能

首先利用水热法制备了由纳米片组装的粒径为1.5–2μm的Bi2WO6微球,然后在微球表面沉积了不同含量的AgCl (5 wt%,10wt%,20wt%,30wt%),制备了异质结构AgCl/Bi2WO6微球光催化剂.利用X射线粉末衍射、扫描电镜、透射电镜、红外光谱、紫外-可见漫反射吸收等手段对所制的光催化剂进行表征,并以紫外光和可见光分别为光源,罗丹明B为降解对象测试了其光催化活性,考察复合不同含量的AgCl对Bi2WO6光催化剂的性能影响.结果表明,沉积AgCl对Bi2WO6的晶体结构、表面性能和光吸收性能没有产生明显影响,但大幅度提高了Bi2WO6的紫外和可见光催化活性.当复合20wt%AgCl时, AgCl/Bi2WO6光催化活性最佳,紫外光下比纯Bi2WO6提高了2.2倍,可见光下提高了1倍.这主要是由于形成的AgCl/Bi2WO6异质结能有效抑制光生电子和空穴的复合,从而提了其光催化性能.     

Synthesis and photocatalytic performance of Ag/AgCl/ZnO tetrapod composites

Ag/AgCl is a visible-light plasmonic photocatalyst that has attracted considerable attention because of its high visible-light absorption and activity owing to the surface plasmon resonance of noble-metal nanoparticles. In this study, Ag/AgCl/ZnO tetrapod composite was prepared by introducing ZnO tetrapods into Ag/AgCl prepared by a polydopamine reduction route. Ag/AgCl was densely deposited on the three-dimensional support framework provided by the ZnO tetrapods. The framework possessed a certain degree of porosity, thereby improving the specific surface area of the Ag/AgCl/ZnO composite. The interaction of ZnO with Ag/AgCl further increased the separation and transfer of electron–hole pairs. The Ag/AgCl/ZnO composite showed excellent photocatalytic activity and good stability. Under xenon lamp irradiation for 20 min, degradation of rhodamine B reached 90%. After four recycling tests, degradation remained stable without any sign of reduction. Ag/AgCl/ZnO tetrapod composite is shown to be a kind of green photocatalyst offering high activity, good stability, and recyclability.

     

AgBr的尺寸及含量对PVA为粘合剂的光敏热成像材料的光敏性的影响

本文以水溶性聚乙烯醇(PVA)为粘合剂,采用异位法合成不同尺寸的立方体AgBr乳剂为光敏元,考察了以硬脂酸银/溴化银为主体的光敏热成像材料体系在可见光区的光敏性与立方体AgBr颗粒尺寸以及含量之间的关系.实验结果表明:在体系中AgBr含银量确定的条件下,AgBr颗粒尺寸在100—200nm范围内,体系的光敏性最大;AgBr与AgSt的银量比在40%左右,体系的光敏性出现最大值;而AgBr乳剂中本身存在的少量明胶对体系的光敏性影响很小.     

Effects of UV irradiation on physico‐mechanical properties of EPDM/buckminsterfullerene composite

Ethylene propylene diene rubber‐fullerene (EPDM/C60) composite, partially crosslinked by ultraviolet (UV) radiation, was prepared and characterized for crosslink density, mechanical properties and thermal behavior. FT‐IR analysis showed peak disappearance at 1688 cm^?1, corresponding to the unsaturation of EPDM, and the appearance of new peaks relating to the formation of oxidation products of C60, such as epoxide, keto, aldehyde and carboxylic groups. Solubility studies demonstrated the dissolution of pristine EPDM in toluene even after a longer period of UV exposure, whereas EPDM/C60 composite became insoluble and/or swollen after 6 hr of UV exposure, indicating the formation of partial crosslinking between EPDM and C60. Differential scanning calorimetry (DSC) measurements revealed an increase in the glass transition temperature peak of UV‐cured EPDM. Thermogravimetric analysis (TGA) showed that UV exposure reduced the thermal decomposition temperature of EPDM/C60, pristine EPDM and dicumyl peroxide (DCP)‐cured EPDM. The modulus, tensile stress and elongation at break of EPDM/C60 composites were greatly influenced by the duration of UV irradiation. Comparison of UV‐cured EPDM/C60 composite with DCP‐cured EPDM confirmed the superior strength properties of the former system. Copyright © 2004 John Wiley & Sons, Ltd.     

共沉淀法制备Ag/AgCl-TiO2空心复合纳米微球及其光催化性能

通过甲基丙烯酸与苯乙烯聚合制备了表面负电性的聚苯乙烯(PSt)纳米乳胶粒. 在乙醇与水的混合溶剂中, 用硅烷偶联剂乙烯基三甲氧基硅烷对其进行表面改性后加入钛酸四丁酯、 氯化钠和硝酸银, 以PSt乳胶粒为模板采用共沉淀法制备了PSt-AgCl-TiO₂复合微球. 在180 ℃对其进行液相预处理及煅烧去除PSt模板后制备了Ag/AgCl-TiO₂空心复合粒子. 对各阶段产物的形貌、 晶体结构和比表面积等进行了表征. 结果表明, 所得产物为Ag/AgCl与锐钛矿型TiO₂复合的空心粒子, 其比表面远大于商品TiO₂(P25). 考察了Ag/AgCl-TiO₂复合粒子在紫外光与可见光下对罗丹明B(RhB)降解的催化活性. 结果表明, 在紫外光下n(Ag)/n(Ti)=0.1%的Ag/AgCl-TiO₂复合粒子活性最高, 30 min时对RhB的降解率比不含Ag/AgCl的TiO₂空心微球提高了13%; 虽然Ag/AgCl-TiO₂在可见光下的催化活性远比紫外光下低, 但与纯TiO₂空心纳米微球相比其催化活性仍明显增强. n(Ag)/n(Ti)=2.0%的Ag/AgCl-TiO₂复合粒子催化活性最高, 120 min时对RhB的降解率比不含Ag/AgCl的TiO₂空心微球提高了38%.     

苯并三氮唑在聚乙烯醇为粘合剂的光敏热成像材料中的化学增感

以水溶性聚乙烯醇(PVA)为粘合剂,硬脂酸银(AgSt)为银源,异位AgBr乳剂为光敏元,考察了苯并三氮唑(BZT)在光敏热成像(PTG)材料中的化学增感效应.实验结果表明:BZT首先增感AgBr乳剂,再与PTG材料的其它组分混合,可以明显提高PTG材料的感光度,而超过一定用量范围则导致影像和灰雾完全消失;在40℃增感温度下,增感70 min可取得最佳感光度;另外,BZT首先与AgSt作用一段时间后,再与PTG材料的其它组分混合,其与AgSt的摩尔比为15%左右,可使得PTG材料取得感光度最佳值.     

Preparation and photocatalytic activity of carbon dot/Ag/AgCl

CD (carbon dot)/Ag/AgCl compound photocatalysts with different compounding degrees were prepared via a precipitation method, and their physiochemical properties were characterized by X‐ray diffraction, FE‐SEM, UV–vis and the like. Through the degradation experiment of methyl orange (MO), the effects of different compounding amount and methyl orange concentration on photocatalytic degradation were investigated to find the best ratio. It was found the photocatalytic activity of CD/Ag/AgCl was significantly higher than Ag/AgCl, and the best compounding dosage was 6 mg/l carbon dot. The degradation rate of CD/Ag/AgCl was lower when the initial MO concentration was higher. Five repeated experiments were conducted to test the stability of the catalysts, and showed the MO degradation rates were all above 85%, indicating the CD/Ag/AgCl compound photocatalysts all showed high stability and repeatability. The reaction mechanism of CD/Ag/AgCl photocatalyst was studied by electrochemical experiments and ESR experiments. The results show that the doping of CD effectively improves the photocatalytic degradation ability of MO.     

火试金法测定铅冶炼渣中的金、银含量

建立了铅冶炼渣中的金银含量的测定方法,采用火试金法富集铅冶炼渣中的金、银,铅扣经灰吹后,形成金银合粒,合粒中除有金银外,还残留微量的铅铋杂质,合粒经硝酸分金后,实现金银分离,得到金粒和分金溶液。合粒中杂质保留在分金溶液中,分金溶液经酸处理,采用电感耦合等离子体发射光谱(ICP-OES)法测定其中杂质量和微量的金量。金粒质量补正分金溶液中微量金量即为样品中的金量,合粒质量减去金粒质量和杂质量即为银量。ICP-OES法测定杂质解决了合粒中铅铋残留和分金失误造成微量金进入分金溶液现象。方法精密度较好,加标回收率分别为银98.6%～100%,金96.2%～102%。方法准确、方便、快捷,能很好地满足铅冶炼渣中金、银含量的测定。     

火试金法测定铅冶炼渣中的金、银含量

建立了铅冶炼渣中的金银含量的测定方法,采用火试金法富集铅冶炼渣中的金、银,铅扣经灰吹后,形成金银合粒,合粒中除有金银外,还残留微量的铅铋杂质,合粒经硝酸分金后,实现金银分离,得到金粒和分金溶液。合粒中杂质保留在分金溶液中,分金溶液经酸处理,采用电感耦合等离子体发射光谱(ICP-OES)法测定其中杂质量和微量的金量。金粒质量补正分金溶液中微量金量即为样品中的金量,合粒质量减去金粒质量和杂质量即为银量。ICP-OES法测定杂质解决了合粒中铅铋残留和分金失误造成微量金进入分金溶液现象。方法精密度较好,加标回收率分别为银98.6%～100%,金96.2%～102%。方法准确、方便、快捷,能很好地满足铅冶炼渣中金、银含量的测定。     

Fabrication of zinc oxide/poly(styrene) grafted nanocomposite latex and its dispersion

Zinc oxide nanoparticles, with an average size of about 40 nm, were encapsulated by polystyrene using in situ emulsion polymerization in the presence of 3-methacryloxypropyltrimethoxysilane (MPTMS) as a coupling agent and polyoxyethylene nonylphenyl ether (OP-10) as a surfactant. Polymerization mechanism of nanocomposite latex was discussed. Transmission electron microscopy (TEM) proved the presence of ZnO nanoparticle appeared to be monodisperse in nanosize in polymer composite particles. ZnO/PS nanocomposites were characterized by Fourier transform infrared spectra (FT-IR), X-ray photoelectron spectroscopy (XPS), thermo-gravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results of FT-IR and XPS revealed that the surface of ZnO particle was successfully grafted by PS through the link of the coupling agent between ZnO and polymer. TGA and DSC results indicated an enhancement of thermal stability of composite materials compared with the pure polymer. SEM (scanning electron microscope) images showed a perfect dispersion of the ZnO particles in latex film. In addition, UV-visible absorption measurements demonstrated that the ZnO/PS composite coatings display a perfect performance of absorbing UV light.     

Large-scale synthesis of size-controllable Ag nanoparticles by reducing silver halide colloids with different sizes

By reducing the colloidal silver halide, we successfully synthesized a series of micro-nano Ag particles.     

外延AgCl/AgBr乳剂感光性能的研究

制备系列AgCl/AgBr八面体外延乳剂,利用EDS-STEM技术对主体乳剂AgBr八面体上氯的分布进行了测定,结果表明随AgCl/AgBr外延乳剂中AgCl含量的增大,而其分布优势始终在AgBr八面体的顶角位置,其次在边。77K时,用375nm的激发光源对外延乳剂AgCl/AgBr样品进行激发,随外延乳剂中AgCl含量的提高,AgCl的发光谱带有增大的趋势,但其峰位置基本保持在510nm左右,AgBr在600nm.AgCl和AgBr的发光峰始终以分立的形式存在,没有混晶AgBrCl的宽谱带出现,外延乳剂AgCl/AgBr的感光度随AgCl含量的提高也有一定的变化规律,当AgCl含量较低时,有明显增感作用,而当AgCl含量过高时,外延乳剂的感光度降低,但灰雾也减小。     

Synthesis and thermal study of octahedral silver nano-plates in polyvinyl alcohol (PVA)

Octahedral silver nano-plates were synthesized from aqueous solution of silver nitrate and polyvinyl alcohol. The colloid formed is dried on glass plates by simple dip-coating method to inhibit the growth of the particles, and to analyze the samples. Samples were characterized by X-ray diffractometer, transmission electron microscope (TEM), thermo-gravimetric analysis (TGA), and differential scanning calorimetry (DSC) techniques. The UV–Vis absorption spectra of these silver nano-plates revealed a high intense plasmon absorption peak near 425 nm. In addition three emission peaks were observed when the excitation was fixed at 222 nm.