核-壳式聚苯乙烯/二氧化硅复合微球及空腔硅球的制备

利用层层自组装的方法制备了粒径和组成可裁剪、具有核-壳式结构的单分散聚苯乙烯(PS)/二氧化硅(SiO₂)复合微球.对复合微球进行热处理除去有机物中心,制备出壁厚可剪裁的空腔硅球.透射电镜(TEM)照片显示二氧化硅纳米颗粒在中心外生成均匀壳层,而煅烧后则可得到轮廓分明的球形空腔;热重分析(TG)说明复合球体的硅含量随着所组装的纳米二氧化硅的粒径的增加而增加;比较PS、SiO₂、复合球体及热处理后的粉体的红外光谱,可分别验证二氧化硅的成功组装和热处理过程中作为中心的PS的完全去除.在吸附相同层的前提下,随着所选用的二氧化硅纳米粒子(10um,20um,40um)的粒径的增大,复合微球的粒径增大,空腔球体的壁厚增加.     

氨基酸辅助制备二氧化硅纳米球及其应用

总结了氨基酸辅助法制备二氧化硅纳米球以及通过种子再生长过程进行尺寸控制的制备方法,对其形成机理进行了探究,介绍了这种二氧化硅纳米球在生物医药、阵列模板、功能薄膜和高分子接枝杂化合成方面的应用,并展望了这种单分散性二氧化硅的应用前景.     

六水氯化钙相变材料过冷性质的研究

CaCl2·6H2O作为一种常低温相变材料(PCM)在蓄热节能领域具有广阔应用前景,但其严重的过冷使应用受到限制.为解决这一问题,本工作基于无机盐成核原理,用溶液法制备了各种掺杂的CaCl2·6H2O晶体,并对其进行了热分析.在开放体系和室温冷却环境下,研究了不同成核剂的添加方法及工艺参数对CaCl2·6H2O的过冷特性的影响及其变化规律.实验结果表明,硼砂和SrCl2·6H2O是CaCl2·6H2O优良的成核剂,分别能将CaCl2·6H2O过冷度降低至2℃和接近0℃,有效地解决了过冷.     

二氧化硅干凝胶的制备与结构分析

以氢氟酸(HF)为催化剂,采用常压干燥法制备了二氧化硅干凝胶,分析了催化剂和干燥条件对干凝胶的影响.通过DTA-TG,IR,BET等测试手段对经热处理的二氧化硅干凝胶的性能进行了研究.结果表明:试样具有纳米多孔结构,并且通过改变干燥方法对比表面积和孔隙率的可提高程度很大.     

二氧化硅溶胶及其自组装薄膜的制备

以氨水为催化剂,通过水解正硅酸乙酯制备了乳白色二氧化硅溶胶,采用静电自组装薄膜技术制备了聚电解质/二氧化硅复合薄膜,并通过热处理制备了二氧化硅薄膜.采用透射电镜、红外光谱仪、721分光光度计对二氧化硅溶胶和薄膜进行了分析.     

单分散二氧化硅形成过程中TEM观察和形成机理

利用透射电子显微镜（TEM）首次观察到了生长过程中的单分散二氧化硅颗粒内部结构.在生长初期,单分散二氧化硅由结构疏松的絮状SiO₂组成;而在生长过程的中后期由结构密实的SiO₂组成．基于TEM观察结果和生长过程中其它现象的研究,提出了单分散二氧化硅形成机理,利用该基理对一些实验现象进行了分析和讨论．     

单分散纳米二氧化硅微球的制备及羧基化改性

采用改进工艺条件的Stober法制备纳米SiO_2微球.用场发射扫描电镜(FESEM)分析了纳米二氧化硅的形貌、粒径.结果表明,通过温度梯度法和控制氨水浓度变化制备出高圆度、单分散、粒径可控的纳米级二氧化硅微球.用KH-550硅烷偶联剂和丁二酸酐对纳米二氧化硅表面羧基化改性.采用X射线能谱仪(EDS)、热重(TGA)、傅里叶红外(FTIR)等手段对改性后纳米二氧化硅的结构、元素种类及含量进行了表征.结果表明,纳米二氧化硅表面成功接枝了羧基官能团.     

二氧化硅基氧化钛光催化材料的制备及其活性研究

用Sol-Gel方法及分步水解工艺制备了二氧化硅/二氧化钛复合粉体,氧化钛在二氧化硅网络中分布均匀,二氧化硅网络能抑制煅烧过程中晶粒的快速生长和锐钛矿相变为金红石相.用碱对粉体进行表面进行改性,不仅能改变化学键,而且能显著提高比表面积并能改变平均孔径尺寸.光催化实验结果表明改性后的粉体有更高的降解率和深度矿化选择性.     

表面Ca2+交联对蒙脱石/聚丙烯酸(钠)吸水保水复合材料性能的影响

采用水溶液聚合法制备了蒙脱石/聚丙烯酸(钠)吸水保水复合材料,并用CaCl2溶液对其进行表面交联处理.本文研究了表面交联剂CaCl2溶液的浓度和表面交联时间对复合材料吸水、保水性能以及凝胶强度的影响.实验结果表明,Ca2+表面交联处理提高了复合材料的保水能力和凝胶强度,同时也使其吸水能力略有下降.     

二氧化硅气凝胶的制备方法研究

二氧化硅气凝胶的制备主要经历溶胶-凝胶过程以及随后的超临界干燥过程.详细描述了这2个阶段的特点,并对不同干燥方法进行了比较.同时也对影响二氧化硅气凝胶结构和性质的因素进行了分析.     

High shear-granulated hierarchically porous spheres nanostructure-designed for high-performance supercapacitors

In this work, the nanosheets-composed porous spheres with a narrow pore size distribution are designed as a rational microstructure configuration of electrode materials for Faraday supercapacitors (FSs). The design of this structure is based on the electrochemical mechanism of FSs, which is beneficial to the redox reactions of electrode materials and the transfer of electrolyte ions to the greatest extent. This structure is built by the interlocking of nanosheets under the high shear mixer-exerted shear force using Zn²⁺ doped Ni(OH)₂ nanosheets as building blocks. It is found that the strong shear force is the driving force for the interlocking of nanosheets. The layer-by-layer growth through the nanosheets interlocking results in the formation of nanostructured spheres designed by us. Due to the appropriate pore structure and the two-dimensional morphology of building blocks, the porous spheres of Zn²⁺ doped Ni(OH)₂ present high electrochemical performance.     

Probing Sodium Storage Mechanism in Hollow Carbon Nanospheres Using Liquid Phase Transmission Electron Microscopy

Carbonaceous materials are promising sodium-ion battery anodes. Improving their performance requires a detailed understanding of the ion transport in these materials, some important aspects of which are still under debate. In this work, nitrogen-doped porous hollow carbon spheres (N-PHCSs) are employed as a model system for operando analysis of sodium storage behavior in a commercial liquid electrolyte at the nanoscale. By combining the ex situ characterization at different states of charge with operando transmission electron microscopy experiments, it is found that a solvated ionic layer forms on the surface of N-PHCSs at the beginning of sodiation, followed by the irreversible shell expansion due to the solid-electrolyte interphase (SEI) formation and subsequent storage of Na(0) within the porous carbon shell. This shows that binding between Na(0) and C creates a Schottky junction making Na deposition inside the spheres more energetically favorable at low current densities. During sodiation, the SEI fills the gap between N-PHCSs, binding spheres together and facilitating the sodium ions' transport toward the current collector and subsequent plating underneath the electrode. The N-PHCSs layer acts as a protective layer between the electrolyte and the current collector, suppressing the possible growth of dendrites at the anode.     

Cu2O的室温液相法合成及光催化性能

采用简单的液相法在室温下制备了八面体与球形的Cu2O粉体,使用扫描电镜（SEM）、X射线衍射仪（XRD）和分光光度计对产物的形貌、晶相和光催化性能进行了检测。结果发现氢氧化钠在控制晶体粒径和形貌方面起到了非常重要的作用,球形Cu2O颗粒尺寸比八面体形貌的Cu/Cu2O小,并提出了不同形貌Cu2O可能的生长机制。研究了在可见光下,所得Cu2O粉在静止状态下对甲基橙溶液的光催化降解效果,结果表明,与八面体形貌的Cu/Cu2O复合材料相比,短时间内,小颗粒球形Cu2O对甲基橙有更高的脱色性能;但经长时间放置于日光中,发现八面体形貌的Cu/Cu2O具有更好的光催化降解性能。     

Template- and surfactant-free synthesis of mesoporous TiO2 spheres with hollow core-shell structure for dye-sensitized solar cells

We have demonstrated a simple and effective hydrothermal route to synthesize titania mesoporous spheres with hollow core-shell structure. The synthesis is free of any surfactants or templates. The formation mechanism is investigated on the basis of the results of time-dependent experiments. The as-obtained mesoporous titania spheres with a specific surface area of 21.5?m²?g^?1 and diameters of 1.2–2.3?μm are composed of anatase titania nanocrystals. The excellent light scattering property of mesoporous titania spheres with hollow core-shell structure is proved. A higher cell efficiency of 8.27% is achieved with mesoporous titania spheres with hollow core-shell structure as a light scattering layer, compared with a cell efficiency of 6.63% for the P25 film electrode with the similar thickness. The higher cell efficiency is attributed to the hollow core-shell structure scattering layer, resulting in excellent pore fitting for electrolyte diffusion, enhanced light scattering ability, and reduced charge recombination.     

仿生矿化的研究Ⅰ．文石型碳酸钙的合成

在聚乙二醇（ＰＥＯ）存在下，ＣａＣｌ２和Ｎａ２ＣＯ３反应生成了类似红鲍鱼壳的含有ＰＥＯ的碳酸钙──高聚物复合材料。Ｘ－衍射和电镜照片显示，它有两种微观结构：外层为文石型和方解石型结构，内层为针状文石型结构。热重分析表明，该材料中含有３％左右ＰＥＯ。结果说明，聚合物对碳酸钙晶核的形成和晶体的生长有很大影响，并对其形成机理进行了初步探讨。     

Structural peculiarities of amorphous germanium films

The number of nuclei grown as a function of time, overpotential and eletrolyte concentration have been investigated experimentally during the electrodeposition of Hg from an aqueous solution of Hg₂(NO₃)₂ onto a plane structureless platinum electrode and a hemispherical single-crystal electrode. It has been established that: (i) at constant overpotential after an induction period the number of nuclei grows linearly with time and reaches a saturation value after a sufficient time has elapsed; (ii) the higher the overpotential the shorter the induction period and the higher both the steady state nucleation rate and the saturation nucleus density; (iii) the smaller the electrolyte concentration the lower the nucleation rate, the longer the induction period and the larger the saturation nucleus density. It is shown that the time dependence of the number of nuclei can be described by an equation derived by assuming that nuclei are formed on active energetically preferred sites on the electrode surface, and that the saturation nucleus density is determined by the deactivation of the active centres by overlapping nucleation exclusion zones. Experimental data confirming the idea of Mutaftschiew and Toschev that the active centres are defects in the oxide layer covering the platinum are presented.     

Spherical CuO synthesized by a simple hydrothermal reaction: Concentration-dependent size and its electrocatalytic application

Spherical CuO was synthesized by a simple hydrothermal reaction with the yield as high as ∼90%. The size of the CuO spheres can be facilely and selectively controlled to range from several hundred nanometers to a few micrometers simply by adjusting the concentration of the reactants. The CuO spheres consist of many small and uniform nanoneedles with tips about tens of nanometers in diameter. Interestingly, it was found that the initial concentration of reactants plays an important role in the formation of spherical CuO with different size. A growth mechanism of spherical CuO was also proposed based on the observed results. The cyclic voltammogrametry reveals that CuO nanospheres exhibit a remarkable electrocatalytic activity for the oxidation/reduction of H₂O₂. This study provides a promising route for the facile and cost-effective synthesis of inorganic nano- and micromaterials, and the synthesized CuO shows great promise in electrochemical applications.     

Bi_2MoO_6空心球的水热沉淀法制备及其光催化性能

以葡萄糖为前躯体,采用水热法制备胶体碳球,以其为模板通过水热沉淀法制备C/Bi2MoO6核壳结构,然后在350℃空气中煅烧,获得了具有良好光催化性能的Bi2MoO6空心球.通过SEM、XRD、FT-IR和BET等测试方法对该催化剂进行了表征;并对其形成机理及反应过程进行了初步探讨,以亚甲基蓝作为被降解物质,研究了其光催化活性。结果表明,Bi2MoO6空心球是由纳米晶粒组成的,壁厚约为30～50nm,平均直径约为0.6～0.8μm,采用胶体碳球作模板时制得的Bi2MoO6空心球比表面积为11.315m2/g,而直接合成的粉体比表面积为3.378m2/g。在黑管灯照射下,2.5h亚甲基蓝的降解率达到了91.95%。     

Microstructure and formation of copper oxide in the Cu electro-polishing process

In this study, the formation of Cu oxide on Cu film is studied during Cu electropolishing in a phosphoric acid-based electrolyte with various Cu ion concentrations, from 2.28% to 10.08%. In cyclic voltammetry measurement, the maximum current density of the anodic peak (Imax) decreases from 38.87 to 28.13 mA/cm2 with increasing Cu ion concentration, indicating that an oxide film forms on the Cu film surface and the thickness increases with Cu ion concentration. Microstructures and crystallography of the oxide film are examined by transmission electron microscopy, which confirms the increase of the oxide film thickness due to the high Cu ion concentration in a H3PO4 electrolyte. Three types of Cu oxide are detected using X-ray photoelectron spectroscopy, namely Cu2O, Cu(OH)2, and CuO. With a Cu-ion electrolyte concentration of less than 6.99%, Cu(OH)2 is dominant, while at higher Cu-ion concentrations, CuO predominates. The formation of CuO protects Cu from corrosion in the electrolyte with the Cu-ion concentration of over 6.99%.     

Facile method for fabricating titania spheres for chromatographic packing

Titania (TiO₂) spheres were fabricated by a solvent evaporation process in which anhydrous ethanol was used as the only solvent. This is a simple and novel route for the fabrication of TiO₂ spheres. The spheres have a narrow particle size distribution and an average diameter of approximately 1.0 µm. The crystal structure of the prepared spheres was improved by high-temperature processing. A possible mechanism for the formation and growth of the spheres is proposed in which titanic acid molecules react with each other through hydroxyl condensation to form primary TiO₂ particles. These aggregate and increase in size by surface reaction, and finally form spheres.