Synthesis of SnO2TiO2 nanocomposite photocatalysts by supercritical fluid combination technology

Acrylic acid, acrylic ester and their ramification have developed quickly in recent years. However, their pro duction process produces a mass of waste water, which when released into the aquatic ecosystem, becomes a source of dramatic disturbance of aquat…     

SnO2中空球和纳米粒子结构的光谱对比分析

以SnCl4.5H2O作为锡源,采用共沉淀法制备SnO_2纳米粒子,以碳球为模板制备了SnO_2中空球。对产物进行了TGA,XRD,TEM,EDX表征,以检测产物的微观结构和形貌为纯SnO_2样品金红石结构。与SnO_2纳米粒子相比,SnO_2中空球结构具有较大的比表面积,因此在表面产生大量的氧空位,造成中空球结构的禁带宽度较小,拉曼光谱中四方金红石的固有模式Eg和A1g发生蓝移现象,SnO_2中空球的PL光谱强度比纳米粒子要强。     

Controlled synthesis of SnO2 with hierarchical Micro/Nano structure

Preparing SnO2 with hierarchical micro/nano structures by hydrothermal, coordination, templating and electrochemical deposition methods and their mechanisms are investigated. The result shows that the echinus-like SnO2 prepared by Method 1 is a typical Ostwald mechanism that develops from internally to externally. The cabbage-like SnO2 by Method 2 is produced with oxalic acid as complexing agent to set-up precursor of SnO2, and then precursors are bocked around the body that is around the body being bocked. The nest-like SnO2 by Method 3 is controlled by citric acid as coordinator for the nucleation as well as the grow rate and setup process. Spongy-like SnO2 by Method 4 is produced using PST as template, PST is be infiltered into SnO2 precursor by gravity and capillary and treated thermally to form a multiporous structure. The petal-like SnO2 by Method 5 is formed with crystal deposition emergence due to oxidation-reduction reactions of two electrodes in an electric field. XRD analyses shows that the five results are all pure phase SnO2. It provides basic data for SnOE industrial application.     

Energy transfer process between Eu3+ and wide-band-gap SnO2 nanocrystals in silica films studied by photoluminescence excitation and time-resolved photoluminescence techniques

Eu3+ions embedded in silica thin films codoped with SnO2 nanocrystals were fabricated by sol–gel and spin-coating methods.SnO2 nanocrystals with controllable sizes were synthesized through precisely controlling the Sn concentrations.The influences of doping and annealing conditions on the photoluminescence intensity from SnO2 nanocrystals are systematically investigated.The effective energy transfer from the defect states of SnO2nanocrystals to nearby Eu3+ions has revealed by the selective photoluminescence excitation spectra.The efficiency of the Forster resonance energy transfer is evaluated by the time-resolved photoluminescence measurements,which is about 29.1%based on the lifetime tests of the SnO2emission.     

A facile method to synthesize 3D structured Sn anode material with excellent electrochemical performance for lithium-ion batteries

Sn anode materials with high specific capacity are an appealing alternative to graphite for next-generation advanced lithium-ion batteries. However, poor electrochemical performance originating from fracture and pulverization due to the enormous volume changes during lithium alloying/dealloying hinders their commercial applications. Here, we propose the synthesis of a novel 3D structured Sn anode material by a facile method: heat treatment of nanosized SnO₂ spheres in a tube furnace with a flowing mixed atmosphere of C₂H₂/Ar at 400 °C. After the heat treatment, the nanosized SnO₂ spheres convert into pure Sn bulk material (~20 μm), which consists of Sn nanowires (~50 nm in diameter and several microns in length). This unique 3D structure with sufficient voids between the nanowires effectively mitigates the volume expansion of Sn bulk material and ensures good electrical contact between the anode material and conducting additives. As a consequence, the 3D structured Sn anode material exhibits a specific reversible capacity of ~600 mA h/g and no significant capacity degradation (compared with that of the 20th cycle) over 500 cycles at 0.2 C.     

钛基金属氧化物阳极的制备及其对有机物废水处理的研究

利用DSA(形稳阳极)电极改性来使电化学具备其他支撑功能.使用电化学氧化方法对模拟苯酚废水进行了降解,制备了锰锑掺杂的钛基Sn O2电极,以期能延长电极寿命,提高降解效率.通过SEM(扫描电子显微镜)、XRD(X射线衍射)、循环伏安曲线、强化寿命测试等方法,对自制电极进行表征和分析,并对影响因素进行了系统研究.结果表明,改性后的DSA电极活性和稳定性有大幅提高,析氧电位达2.3 V,加速寿命达42 h,在最佳条件下处理质量浓度为100 mg/L的苯酚废水,去除率在8 h后达到89.26%.     

燃油液滴高压蒸发规律探讨

在分析燃油液滴高压蒸发规律与常压下ｄ２蒸发规律间差别的基础上，考虑液滴表面移动速率和燃油物性参数的变化，建立了高压下计算液滴温度和蒸发速率的基本方程，并计算了正庚烷（Ｃ７Ｈ１６）在各种温度和压力下的蒸发特性．结果表明，高压有利于燃油液滴蒸发，但即使环境压力超过燃油的临界压力，其平衡蒸发温度也未必能达到临界温度     

基于SnO2/TiO2/Au NPs纳米复合材料发展光电化学方法特异性检测唾液酸

制备了氧化铟锡（ITO）/二氧化锡（SnO₂）/二氧化钛（TiO₂）/金纳米粒子（Au NPs）纳米复合电极（ITO/SnO₂/TiO₂/Au NPs）,并利用它发展了可以选择性检测唾液酸（SA）的光电化学（PEC）法.采用旋涂法制备了ITO/SnO₂电极,并通过静电纺丝和磁控溅射技术在ITO/SnO₂表面原位合成了TiO₂纳米纤维和Au NPs.与单纯SnO₂比,ITO/SnO₂/TiO₂/Au NPs纳米复合电极的光电性能显著提高.这可能与Au NPs的局域表面等离子体共振效应（LSPR）和TiO₂/SnO₂异质结之间的协同作用密切相关.之后,通过金硫键（Au-S）将四巯基苯硼酸（4-MPBA）修饰在ITO/SnO₂/TiO₂/Au NPs电极表面,利用4-MPBA和SA之间的非特异性酯化反应,发展了可以特异性检测SA的PEC传感平台.     

添加剂对SnO2气敏特性的影响

The conductivity and the gas seletivity of SnO₂ gas-sensing material are carried out with the formation of lacking oxygen and oxidizing process.The higher the density of lacking oxygen is,the more the gas-sensing effect is obvious.According to the gas-sensing mechanism,the influence of additives of Sb₂O₃ and PdCl₂ on the conducdivity and the selectivity of SnO₂gas sensor is studied here.The applied mechanism of additive on the gas-sensing characteristics of SnO₂ is analyzed.     

Partial oxidation of methane to syngas in a mixed-conducting oxygen permeable membrane reactor

Mixed-conducting oxygen permeable membranes represent a class of novel ceramic membranes, which exhibit mixed oxygen ionic and electronic conductivities. At high temperatures, oxygen can permeate through the membrane from the high to low oxygen pressure side under an oxygen concentration gradient. Theoretically, the permselectivity of oxygen is 100%. Recently, a novel mixed-conducting membrane—Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3−δ has been developed, which shows extremely high oxygen permeability and promising stability. Furthermore, the reactor made with such membranes was successfully applied to the partial oxidation of methane to syngas reaction using air as the oxygen source, which realized the coupling of the separation of oxygen from air and the partial oxidation of membrane reaction in one process. At 850°C, methane conversion > 88%, CO selectivity > 97% and oxygen permeation rate of about 7.8 mL/(cm² · min) were obtained.     

Nanostructured SnO2 photoanode-based dye-sensitized solar cells

This review focuses on recent developments in the nanostructured SnO2 photoanodes for dye-sensitized solar cells （DSSCs） applications. Carefully designed and fabricated nanostructured SnO2 films are advantageous for effective improvement in performance of DSSCs. Nano- crystals can offer a large surface area for dye adsorption; nanowires are able to provide a direct transfer pathway for the rapid collection of photogenerated electrons; the mes- oporous, monodisperse beads with a submicrometer-sized diameter ensure a large specific surface area for dye adsorption and simultaneously promote light scattering; the surface modification of SnO2 by other oxides may improve the photovoltage and photocurrent, hence resulting in the higher power conversion efficiency of SnO2-based DSSCs.     

Solidification microstructure and phase constitution of Fe-7.5%Mo-16.5%Si ternary quasiperitectic alloy

Solidification of Fe-7.5%Mo-16.5%Si ternary quasiperitectic alloy is investigated by using differential scanning calorimetry (DSC) and drop tube containerless processing techniques.The primary phase is identified as R (Fe5Mo3Si2) and the quasiperitectic phases are τ1 (Fe5MoSi4) and Fe3Si.With the decrease of droplet diameter, the cooling rate and undercooling of the droplets in-crease rapidly.The experiment result indicates that the solidification microstructure is composed of remnant primary phase, qua-sip...     

氮化碳自组装包裹对SnO2TiO2复合锂离子电池负极材料电化学性能的影响

通过简单的石墨相氮化碳(g-C₃N₄)纳米片自组装沉积法,制备了g-C₃N₄包裹的SnO₂-TiO₂纳米复合材料.扫描电子显微镜观察显示,g-C₃N₄均匀地包裹在SnO₂-TiO₂纳米颗粒上.SnO₂-TiO₂-C₃N₄纳米复合材料被用作锂离子电池的负极材料,在0.2C的倍率下循环20次后,比容量达到380.2 mA·h·g^-1,明显高于未经g-C₃N₄包裹的纯的SnO₂(51.6 mA·h·g^-1)和SnO₂-TiO₂纳米复合材料.在0.1~0.5C的倍率充放电测试中,SnO₂-TiO₂-C₃N₄纳米复合材料的比容量仅从490 mA·h·g^-1衰减到330 mA·h·g^-1,高倍率下抗衰减性能优于同类材料.材料优异的电化学性能归功于g-C₃N₄的包裹处理,这不仅增强了固体电解质界面(SEI)的稳定性,也抑制了锂离子嵌入-脱出时SnO₂和TiO₂纳米颗粒的体积变化.     

柴油、甲醇和水三组元乳化液滴微爆过程的研究

分别采用激光全息摄影技术和高速数字摄影技术观察了柴油、甲醇和水乳化液喷雾在高温高压（773K，3．1MPa）环境中发生微爆现象的瞬间和全过程，证实了微爆现象的存在．由于微爆机理的复杂性，尚难以用数学方法准确描述该过程．实验分析表明：若环境温度处于“最佳温度”范围内，乳化液滴表面首先形成“无水层”，液滴内部形成一个水滴的概率很小，可能形成几个相对较大的水滴，只要其中一个较大水滴的蒸汽压力大于液滴的表面张力和环境压力之和，液滴就有可能发生微爆，微爆不仅与液滴直径、组分的质量分数和组分间的沸点差等乳化液的本身特性有关，而且环境温度和压力的影响也不容忽视．该研究可以为乳化液喷雾微爆过程的数学模拟提供参考．     

撞击液滴形成的液膜边缘特性

以旋风分离器内液滴撞击筒壁为研究背景,探讨了撞击形成的液膜边缘特性,考察了韦伯数(We)、撞击速度、初始液滴直径对液膜边缘形成的指形液滴和卫星液滴的影响.结果发现:不同We数下,最大液膜直径形成的指形液滴体积分布集中在0.2～0.6,近似于高斯分布;随着We数的增加,大体积卫星液滴出现的几率也随之增大;且卫星液滴的体积随着初始液滴直径和初始撞击速度的增大而增大;另外,在同一铺展过程中,边缘液滴、指形液滴和卫星液滴三者的数量呈依次递减的关系.     

D4阳离子型细乳液的制备及其稳定性

八甲基环四硅氧烷(D₄)细乳液聚合的成核场所是单体液滴，其液滴尺寸决定了聚合机理与乳液稳定性。文中研究了D₄阳离子型细乳液的制备技术及其静置稳定性和离心稳定性。结果表明助乳化剂的溶解与扩散、乳化剂对单体液滴的覆盖程度，助乳化剂与乳化剂的协同作用、均质化强度对成核方式和细乳液稳定性均有显著影响。通过均质化分散技术，在少量乳化剂和助乳化剂存在下，制备了窄分布、平均粒径小于100nm的稳定的D₄细乳液，可实现D₄阴离子开环细乳液聚合。     

球形液滴法测液体的表面张力系数

利用液体表面张力系数与液滴半径及液体附加压强成比例的关系,通过螺旋式微量调旭器,控制凸出液体球的半径大小,测量丫不同半径液滴球的附加压强与液体表面张力系数,该装置还增加了温度传感器和』Jll热器,可以在密闭窄内测量不同温度下液体的表面张力系数,避免了外界环境的干扰,提高了实验精度．     

Molecular dynamics simulation of wetting behavior at CO2/water/solid interfaces

We used molecular dynamics simulation to demonstrate the microscopic wetting behavior of two solid model surfaces for the first time. Hydrophilic and hydrophobic features were modeled in a dense CO₂ fluid environment under various densities. The water droplet loses contact with the surface under the influence of higher density CO₂ fluids on the hydrophobic surface. For the hydro-philic surface, no separation between the water droplet and the surface was observed. However, the contact angle of the water droplet on the hydrophilic surface was found to increase with the fluid density. The effect of dense CO₂ fluid on the surface wettability can be interpreted in terms of enhanced interactions from the surrounding CO₂ molecules.     

CuO掺杂纳米SnO2锂离子电池负极材料的合成与电化学性能

以SnCl₄·5H₂O、Cu(NO₃)₂·3H₂O和NH₃·H₂O为原料,采用化学共沉淀法制备了CuO掺杂的纳米SnO₂粉末.运用X射线衍射、扫描电镜等手段对合成粉末进行了表征.将合成粉末作为锂离子电池负极材料,研究了其充放电容量、循环性能和交流阻抗等电化学性能.结果表明：采用化学共沉淀法可以得到平均粒度为87 nm的CuO掺杂的纳米SnO₂粉末;在SnO2中掺入CuO,并没有改变SnO₂的结构,但能够有效抑制SnO₂粒子的长大;CuO掺杂的纳米SnO₂粉末的可逆容量可以达到752 mA·g^-1,经60次循环后,CuO掺杂的纳米SnO₂粉末的容量保持率分别为93.6%,优于纳米SnO₂ (92.0%),掺杂CuO改善了纳米SnO₂的循环性能.     

Effects of substrate temperature and ambient oxygen pressure on growth of Ba(Fe1/2Nb1/2)O3 thin films by pulsed laser deposition

Ba(Fe1/2Nb1/2)O3 thin films were grown on Pt/TiO2/SiO2/Si substrates with pulsed laser deposition (PLD) at temperatures ranging from 823 to 923 K with the varied ambient oxygen pressure. X-ray diffraction (XRD) data confirmed the single phase of polycrystalline Ba(Fe1/2Nb1/2)O3 thin films. The effects of substrate temperature and ambient oxygen pressure on the surface morphologies of the thin films were investigated by atomic force microscopy (AFM) and the growth dynamics of thin films was discussed. Larger grains and denser surface morphologies were observed with increasing substrate temperature. While finer grains were produced with increasing ambient oxygen pressure due to more frequent collisions between the ejected species and ambient oxygen molecules. The influence of the substrate temperature and ambient oxygen pressure on the dielectric properties was also discussed. Improved dielectric constant and decreased dielectric loss was observed for the thin film deposited at evaluated temperature.