纳米氧化镍的制备及表征

以尿素、NiCl2·6H2O为原料,采用均相沉淀法制备了前驱体Ni(OH)2,再经高温煅烧,得到纳米氧化镍。用TG DTA热分析、X射线衍射(XRD)、扫描电镜观察(SEM)等测量方法对氧化镍前驱体的热分解过程、纳米氧化镍颗粒的晶体结构、粒径和形态进行了研究。     

燃烧-还原法制备镍纳米微粒

采用燃烧法制备纳米氧化镍前驱体．再用氢气还原。得到了镍纳米微粒。利用XRD、TEM对样品的成分、晶体结构和形貌进行了分析。结果表明．所制得的镍纳米颗粒纯度高。粒径分布为40～100nm。呈较规则的球形链状分布。最佳反应温度为300℃．反应时间为2h．制备氧化物前驱体时甘氨酸和硝酸根的最佳配比(GIy／NO3^-)为0．25。     

纳米硫酸钡制备过程中的蒸馏法破乳和微孔液的循环使用

以硫酸钠和氯化钡的W／O型微乳液反应制备纳米硫酸钡为实验体系,利用微乳液中各组分沸点的差异,提出了利用蒸馏法破坏微乳液,实现纳米颗粒与微乳液体系的分离以及微乳液循环利用的新工艺。研究了破乳时蒸馏温度、循环使用时体系中的盐浓度、含水量等因素对纳米颗粒品质的影响,比较了蒸馏法破乳和加高浓度盐、升高温度等方法破乳对纳米颗粒回收率的影响。实验结果表明,蒸馏温度升高不会导致纳米颗粒的团聚,随着循环次数的增加,粒径从第一次制备的14nm增加到第五次制备的25nm,但单分散性和分布仍然良好;体系中水含量过大,制备出的纳米颗粒粒径不均一;此外蒸馏法破乳回收纳米颗粒的收率可以达到82％,高于加盐破乳和升温破乳的回收率。     

复合掺杂的纳米二氧化锡粒子的制备与表征

分别采用微乳液法（辛基酚聚氧乙烯醚＋正己醇／环己烷／水组成的微乳液体系）和柠檬酸溶胶-凝胶法制备了镁与铈、锌、锆复合掺杂的纳米二氧化锡颗粒，通过热分析（TG-DTA）、X射线衍射（XRD）、比表面积测定（BET）、红外吸收光谱（FT-IR）和紫外-可见光谱（Uv-Vis）对其结构进行表征。结果表明，两种方法制备的产物均为金红石结构，微乳液法制备的颗粒较后者具有较小的晶粒粒径、较大的比表面积和紫外吸收边；复合掺杂后，样品的粒径减小，比表面积增大，样品的紫外-可见吸收发生红移；其中，镁-铈复合掺杂的样品具有最小的晶粒粒径和最大的比表面积，分别为4．53nm和78．50m^2／g；复合掺杂能够抑制二氧化锡颗粒生长，增大其比表面积。     

水热法制备纳米氧化镍

以硝酸镍为原料,氢氧化钠为沉淀剂、聚乙二醇为分散剂,采用水热法获得前驱体,然后经煅烧制备纳米氧化镍粉体。采用XRD、SEM和TEM对其结构和形貌进行表征。研究了溶液的pH,水热反应温度、热处理温度对纳米氧化镍结构和形貌等影响。     

正交试验优化纳米氧化锌前驱体乳液合成工艺

以醋酸锌和氨水为原料,结合并流沉淀和超声处理制备纳米氧化锌的前驱体乳液。再利用真空冷冻干燥方法得到前驱体,经过热处理得到纳米氧化锌(约15nm)。用正交试验方法分析了乳液制备工艺对其稳定性的影响,结果表明:分散剂加入量对前驱体乳液稳定性影响最大,合适的分散剂加入量为0.4%(体积分数)。     

热处理温度对钇铝石榴石(Y3Al5O12)析晶的影响

透明YAG多晶陶瓷具有优良的光学、机械与化学性能,逐渐成为新一代固体激光基质材料.分散均匀、团聚轻、超细颗粒的纳米前驱体粉末有利于制备出高度透明的激光陶瓷.以Y2O3,Al(NO3)3·9H2O和柠檬酸为原料,采用柠檬酸-凝胶法和低温自蔓延燃烧反应相结合制备出黑色粉末,经1100℃烧结出YAG纳米前驱体粉末.采用TG-DTA,XRD,FT-IR和TEM测试手段对YAG前驱体粉末进行表征,采用谢莱公式计算出不同烧结温度下晶粒尺寸.研究结果表明:随热处理温度升高,晶粒平均尺寸增加,标准偏差以小幅度增加,晶粒尺寸分布曲线保持一致,晶格参数减小.随热处理时间增加,晶粒主要以晶界扩散形式线性长大.纳米晶粒表面原子呈不规则分布,导致晶格参数增加,前驱体颗粒由单个晶粒所构成.     

纳米二氧化硅粉末的制备

采用微乳液法制备了高比表面积纳米SiO2粉末，考察了微乳液体系的配制、反应物浓度、反应温度、焙烧温度、共沸蒸馏脱水工艺制备的纳米SiO2性能的影响，并通过比表面积（BET）、透射电镜（TEM）、红外光谱分析（IR）、X射线衍射（XRD）对样品进行了表征。结果表明，粉末制备的工艺参数对样品性能影响较大，在较佳工艺条件下制备的纳米SiO2粉末近似呈球形，粒径为15～30nm，比表面积高达580-630m^2／g。共沸蒸馏工艺能充分地脱去凝胶中残余的水分，防止因含水胶体干燥过程引起的粉末硬团聚，从而显著地提高了粉末的性能。     

纳米二氧化硅粉末的制备

采用微乳液法制备了高比表面积纳米SiO2粉末，考察了微乳液体系的配制、反应物浓度、反应温度、焙烧温度、共沸蒸馏脱水工艺制备的纳米SiO2性能的影响，并通过比表面积（BET）、透射电镜（TEM）、红外光谱分析（IR）、X射线衍射（XRD）对样品进行了表征。结果表明，粉末制备的工艺参数对样品性能影响较大，在较佳工艺条件下制备的纳米SiO2粉末近似呈球形，粒径为15～30nm，比表面积高达580-630m^2／g。共沸蒸馏工艺能充分地脱去凝胶中残余的水分，防止因含水胶体干燥过程引起的粉末硬团聚，从而显著地提高了粉末的性能。     

纳米光触媒的合成工艺及其应用研究

以硫酸氧钛为原料通过常温水解沉淀及水热处理制备了纳米光触媒乳液.考察了水解pH值、稳定剂、氧化剂、热处理温度及热处理时间等条件对该乳液的光催化性能的影响.XRD和TEM检测结果表明:光触媒乳液中纳米TiO2颗粒晶体结构为锐钛型,平均粒径为10 nm.光催化活性评价表明:当水解溶液的pH值=8,以柠檬酸为稳定剂,在100 ℃下水热处理6 h后获得的纳米光触媒乳液具有最佳光催化活性.     

Fabrication and characterization of NiO nanoparticles by precipitation from aqueous solution

Present work involves synthesis of NiO nanoparticles using chemical homogeneous precipitation (CHP) method as a facile procedure. Ammonia as a complex agent was used in this method. Effects of different types of complexation-precipitation methods on the crystallinity and morphology of nanoparticles were investigated. NiO particles were prepared by direct precipitation method from NiSO₄ solution to compare crystallinity and morphology of NiO particles with particles obtained via complexation-precipitation methods. Our major intent was to investigate the effect of complex agent on the crystallization and growth of NiO nanoparticles. Results showed that the best condition for synthesizing spherical NiO shape was using NaOH as decomposing agent, of which the consequence was more uniformity and spherical nanoparticles with a diameter in the range of 40–60 nm. The size of the nickel oxide and nickel hydroxide nanoparticles was estimated by X-ray powder diffraction (XRD) pattern. The chemical structure information of the particles was studied by Fourier transform infrared (FT-IR) spectroscopy. Spherical, elliptical, sheet or flowerlike shapes were detected by field emission scanning electron microscopy (FESEM) analysis. Results showed that by the use of ammonia as complex agent, crystalline state and particles size distribution of NiO nanoparticles improved.     

反相微乳法制备纳米V2O5

采用十六烷基三甲基溴化铵(CTAB)/正丁醇/正辛烷/水溶液微乳体系成功制备了纳米V2O5。先采用反相微乳法分别制备碱性偏钒酸铵微乳液和稀硫酸单相微乳液,再将两种微乳液混合得到V2O5前驱物,经陈化、洗涤、干燥、焙烧得到纳米V2O5。通过测定电导率分析了微乳体系的稳定性,采用FTIR、XRD、TEM对纳米V2O5的结构、成分、晶形、粒径等进行了表征。结果表明,采用反相微乳法制备的纳米V2O5为球形、分散性较好、颗粒粒径为6～20nm。     

反相微乳法制备纳米V_2O_5

采用十六烷基三甲基溴化铵（CTAB）/正丁醇/正辛烷/水溶液微乳体系成功制备了纳米V2O5。先采用反相微乳法分别制备碱性偏钒酸铵微乳液和稀硫酸单相微乳液,再将两种微乳液混合得到V2O5前驱物,经陈化、洗涤、干燥、焙烧得到纳米V2O5。通过测定电导率分析了微乳体系的稳定性,采用FTIR、XRD、TEM对纳米V2O5的结构、成分、晶形、粒径等进行了表征。结果表明,采用反相微乳法制备的纳米V2O5为球形、分散性较好、颗粒粒径为6～20nm。     

Preparation and characterization of platinum-ruthenium bimetallic nanoparticles using reverse microemulsions for fuel cell catalyst

Platinum-ruthenium bimetallic nanoparticles are prepared by chemical reduction using sodium borohydride in reverse microemulsions of water/isooctane/Igepal CA-630/2-propanol for fuel cell catalysts. The prepared nanoparticles are characterized by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and energy-dispersive X-ray analysis. The average size and morphology of nanoparticles are dependent on the water volume fraction in reverse microemulsion system in the range of ca. 2-4 nm. The morphology of particles is related with the percolation behavior of water droplets in reverse microemulsions. By the pretreatment of water phase using a hydrochloric acid, the particles of a homogeneous solid solution state can be obtained. The CO stripping cyclovoltammetry and the electrochemical measurements compared with commercial catalyst show that the prepared particles have a high electrochemically active surface area and a stable and high catalytic activity for reformate gas oxidation.     

微乳液法制备CdTe纳米颗粒的表征

CdTe纳米晶作为一种重要的Ⅱ-Ⅵ族半导体材料,在LEDs、光子学材料和生物标记等方面已被应用。本实验利用CTAB／环己烷／异丁醇／水作为反应介质,氮气保护下在微乳液体系中制备了CdTe纳米颗粒。利用X射线衍射（XRD）、透射电子显微镜（TEM）、扫描电子电镜（SEM）表征了CdTe纳米颗粒的形貌和粒径尺寸,研究水与表面活性剂摩尔比以及陈化时间对CdTe纳米颗粒的影响,结果表明当水与表面活性剂摩尔比为40,陈化时间为24h时制备出了产量高,稳定性好的直径为40-50nm的CdTe纳米颗粒。     

硫酸钡微/纳结构材料的微乳液合成与形貌控制

在十六烷基三甲基溴化铵（CTAB）/环己醇/水三组分体系的水包油（O/W）、油包水（W/O）和油水双连续结构区域,以相应盐的水溶液代替水构成3种典型的微乳液体系,分别制备了不同形貌的硫酸钡微/纳结构材料,并通过透射电镜（TEM）、X射线衍射（XRD）手段对所制样品进行了表征。结果表明,微乳液的结构对形成无机盐晶粒的尺寸和形貌能够产生影响,同时CTAB在晶粒表面吸附可能对晶粒的生长起一定的导向作用。     

Synthesis,Stabilization and Activation of Pt Nanoparticles for PEMFC Applications

Amongst the main challenges of catalyst materials for Proton Exchange Membrane Fuel Cells (PEMFCs) are activity and durability. Here we report on the synthesis of monodisperse nanoparticles and stabilization with traces of the surfactant, here Na‐AOT (bis‐(2‐ethylhexyl) sulfosuccinate sodium salt), used in the synthesis procedure. The surfactants prevent agglomeration and reduce Ostwald ripening. We compare the performance of Pt catalyst nanoparticles synthesized in dense microemulsions, Na‐AOT/heptane/water and Triton X‐100/toluene/water, with a commercial state‐of‐the‐art catalyst for the Oxygen Reduction Reaction (ORR). The produced catalyst nanoparticles were extracted onto a carbon support, Vulcan XC‐72R, washed and activated by heat‐treatment, which led to heavy agglomeration, or by electrochemical treatment, which led to an enhanced activity for ORR. Additionally, in comparison to the other two catalysts an increased durability of the platinum nanoparticles synthesized in the microemulsion of Na‐AOT/heptane/water was observed.     

草酸锌纳米粒子的合成动力学研究

以微乳液和均匀沉淀耦合法制备出纳米草酸锌粒子。为了研究纳米粒子生长的动力学特征,用稀释法求取了该过程所涉及的NP-9／正己醇／正庚烷／硝酸锌溶液微乳液体系的水核半径：检测了草酸二甲酯与硝酸锌的沉淀反应过程中浓度随时间的变化,建立了草酸二甲酯水解的动力学方程。根据微乳液法制备纳米粒子的扩散机理,推导出纳米粒子的粒径与反应时间的关系式,并将计算所得粒径与实验值进行对比。结果表明：NP-9／正己醇／正庚烷／硝酸锌溶液微乳液体系的水核半径在308K和318K分别为186nm和233nm,可以作为制备纳米粒子的微反应器。在有沉淀反应发生时,草酸二甲酯的水解为一级反应;草酸锌纳米粒子粒径的实验值比计算值大15～30倍,其生长的动力学过程可依照碰撞-融合-分裂机理解释。     

A comparison of mechanochemical methods for the synthesis of nanoparticulate nickel oxide

In this study, mechanochemical processing has been investigated as a means of manufacturing nanoparticulate powders of NiO. Two different reactant mixtures were examined and compared. The first system was based on mechanical milling of Ni(OH)₂ with NaCl diluent. Milling of this reactant mixture resulted in disintegration of the Ni(OH)₂ precursor and its progressive dispersal into the NaCl matrix. Subsequent heat treatment and washing yielded a nanocrystalline powder of NiO, which contained a significant proportion of particles with an unusual platelike morphology. The second system that was examined was based on mechanically activated reaction of NiCl₂ + Na₂CO₃ + 4NaCl. Milling resulted in mixing and microstructural refinement of the reactant mixture. Chemical reaction during post-milling heat treatment resulted in the formation of a powder consisting of nanocrystalline NiO grains embedded in NaCl. Removal of the NaCl by washing with water yielded NiO nanoparticles with an equiaxed particle shape.