溅射气压对非晶Hg1-xCdx Te薄膜微观结构和化学组分的影响（英文）

采用射频磁控溅射制备了非晶态结构的Hg1-xCdxTe薄膜,并利用台阶仪、XRD、原子力显微镜、EDS等分析手段对薄膜生长速率、物相、表面形貌、组分比例进行了研究。实验结果表明,溅射气压对薄膜生长速率、微观结构、表面形貌和化学组分有直接影响。随着溅射气压增大,其生长速率逐渐降低。当溅射气压高于1.1 Pa时,薄膜XRD图谱上没有出现任何特征衍射峰,只是在2θ=23°附近出现衍射波包,具有明显的非晶态特征;当溅射气压小于1.1 Pa时,XRD谱表现为多晶结构。另外,随着溅射气压的增加,薄膜表面粗糙度逐渐减小,而且溅射气压对薄膜组成的化学计量比有明显影响,当溅射气压为1.1 Pa时,薄膜中Hg的组分比最低,而Cd组分比最高。     

氧化石墨制备温度对石墨烯结构及其锂离子电池性能的影响

采用改进的Hummers 法, 以石墨粉为原料制备氧化石墨, 然后使用微波还原法制备石墨烯, 最后以石墨烯作为负极材料组装锂离子电池. 系统的研究了高温氧化阶段中温度对氧化石墨的氧化程度、石墨烯的还原程度和比表面积以及锂离子电池性能的影响. 利用场发射扫描电镜(FESEM)、 X射线光电子能谱(XPS)、X射线衍射仪(XRD)、BET测量仪对氧化石墨和石墨烯的微观结构及比表面积等进行测试和表征. XRD, XPS及电化学测试的结果显示当高温阶段氧化温度为90 °C时, 氧化石墨的氧化程度最高, 相应的石墨烯也具有最高的还原程度和最大的比表面积423.2 m²/g, 同时石墨烯锂离子电池也具有更好的性能: 首次放电比容量为1555.5 mAh/g, 充电容量为1024.6 mAh/g, 其循环放电比容量达到600 mAh/g.     

紫外光下纳米TiO2薄膜亲水性机理的电化学研究

利用溶胶 凝胶方法在透明导电玻璃ITO (SnO2 ∶In)表面制备纳米TiO2 薄膜 ,XRD谱图表明TiO2 是锐钛矿晶型 ,AFM (Atomic Force Microscope)测得薄膜表面粒子约为 10 0nm .研究了ITO表面纳米TiO2 薄膜的光致亲水性变化 .通过循环伏安技术测定TiO2 薄膜电极在 2 5 3.7nm的紫外光照射后的电化学行为推测光致亲水性机理 .发现在紫外光照射一定时间后 ,TiO2 薄膜电极的循环伏安图在 +0 .0 35V处出现新的氧化峰 ;且随光照时间的增加 ,氧化峰的峰电流增大 ,溶液中的溶解氧对峰电流的大小有明显影响 .实验表明 ,在紫外光照下电极表面有Ti3 + 产生 ,证实了TiO2 薄膜的光致亲水性转变过程与Ti3 + 的生成导致的表面结构变化有关     

纳米结构锌及锌氧化物薄膜对甲基橙的降解作用研

采用磁控溅射方法制备了纳米金属锌薄膜,结合后续的空气退火处理制备了纳米锌氧化物薄膜. 金属锌薄膜对甲基橙的还原降解以及锌氧化物薄膜对甲基橙的光催化降解过程都可以用一级反应动力学方程来描述. 甲基橙溶液在金属锌膜的还原降解下具有最快的褪色速率,但矿化不完全：在紫外光波段出现的额外吸收峰表明生成了芳香族中间产物. 完全氧化的氧化锌薄膜对甲基橙的光催化降解速率仅为金属锌膜还原降解速率的1/4左右,没有出现芳香族中间产物. 另外实验发现部分氧化的锌氧化物薄膜对甲基橙的光催化降解速率明显高于完全氧化的氧化锌薄膜,光催化活性的提高可能由于部分氧化薄膜中同时存在的金属锌及氧化锌相之间的协同效应.     

Mg2Ni纳米贮氢合金电极的电化学性能

测定了Mg2Ni纳米贮氢合金电极在扫描速率份别为10，20，40，80，160mV／s时的循环伏安曲线。从曲线上读出不同扫描速率时的阴极峰电流Ipc，阳极峰电流Ipa，阴极峰电势Epc，阳极峰电势Epa，数据列于表1。作Ipc-v^1/2关系图，如图1所示。     

碳气凝胶及活化碳气凝胶电极材料制备与性能

 以间苯二酚(R)-甲醛(F)为原料,制备了有机气凝胶和碳气凝胶,并对其进行二氧化碳活化。X射线衍射(XRD)测试表明,二氧化碳渗入到碳气凝胶网络结构发生反应,造成(002)峰和(100)峰减弱;扫描电子显微镜(SEM)测试表明,活化没有破坏碳气凝胶的骨架结构,而是增加了大量的nm尺度微孔,从而大大提高了碳气凝胶的比表面积和微孔比例。在1 mol/L KOH电解液中进行了循环伏安和计时电位扫描测试,电极材料电化学性能稳定,具有较好的可逆性,在1 mA/s电流密度下进行充放电测试,得到活化前电极比电容为103 F/g,活化后由于比表面积的增加,比电容达到371 F/g,是一种理想的电化学电极材料。     

不同升温速率下微米级铝粉的氧化特性分析

采用热重-质谱联用仪(TG-MS)、X射线衍射仪(XRD)及扫描电子显微镜(SEM)等测试手段,研究了不同升温速率下1～2μm铝粉的氧化特性,并分析了氧化膜厚度和反应活化能与升温速率的关系。结果表明,多晶相变机理同样适用于1～2μm铝粉,其氧化可分为五个阶段。氧化铝晶形转变、铝核心熔化膨胀等引起的氧化膜破裂是快速氧化的主要原因;第三阶段因θ-Al_2O_3出现导致DTG曲线出现较小的增重峰,该峰值温度随着升温速率的减慢而提前。结果还发现扩散驱动力的选择对计算活化能产生的影响比较小,各个阶段的活化能与升温速率关系不完全统一。     

现场时间分辨拉曼光谱研究不同pH值溶液中聚吡咯电极的氧化还原和降解

对不同ｐＨ值溶液中聚毗咯的电化学氧化还原行为进行了现场时间分辨拉曼光谱研究。结果表明，采用拉曼－循环伏安图可以克服充电电流给聚吡咯氧化还原峰电位的确定带来的困难。本文讨论了拉曼－循环伏安图中峰电位相对于常规循环伏安图中的氧化还原峰电位发生负移的原因。在酸性溶液中氧化还原时会出现与一定氧化程度的、质子化的聚吡咯链段有关的不稳定中间产物，这是常规拉曼光谱所不能获得的，体现了电化学现场时间分辨拉曼光谱方法的优越性。     

纳米银导电膜的制备及其光谱学分析

为了以温和的化学反应制备纳米银导电膜,在PET薄膜上涂布柠檬酸银乳液,并用抗坏血酸(Vc)还原,用红外光谱仪、紫外-可见光分光光度计、X射线衍射仪(XRD)、扫描电子显微镜、原子力显微镜等,研究柠檬酸银乳液及其还原涂层的微观形貌、晶体结构和导电性能。发现PVP保护的柠檬酸银乳液粒径分布在60～150 nm。银膜的UV-Vis吸收峰位于430 nm,表明其具有纳米结构。XRD分析表明,还原后的涂层形成了不完整的银晶体,水洗比乙醇处理更能促进柠檬酸银的彻底还原和银膜的晶型完善,降低银膜表面电阻。     

现场时间分辨拉曼光谱研究不同pH值溶液中聚吡咯电极的氧化还…

对不同ｐＨ值溶液中聚吡咯的电化学氧化原行为进行了现场时间分辨拉曼光谱研究，结果表明，采用拉曼－循环伏安图可以克服充电电流给聚吡咯氧化还原峰电位的确定带来的困难。本文讨论了拉曼－循环伏安图中峰电位相对于常规循环伏安图中的氧化还原峰电位发生负移的原因。在酸性溶液中氧化还原时会出现与一定氧化程度的，质子化的聚吡咯链段有关的不稳定中间产物，这是常规拉曼光谱所不能获得的，体现了电化学现场的时间分辨拉曼光谱方     

Structural and electrochemical properties of polythiophene

Polythiophenes (PTs) were prepared by chemical oxidative polymerization method in presence and absence of three different (cationic - CTAB, anionic - SDS and non-ionic - Triton X-100) surfactants using FeCl₃ as oxidant. The prepared PTs were characterized by FT-IR, UV-Vis, XRD, SEM and cyclic voltammetry studies. The FT-IR spectra inferred the polymerization of thiophene and elucidate the corresponding functional groups of PTs. Our results on the UV-Vis spectra demonstrate the n−π* electronic transition of the conjugated molecules. Further the red shift in the absorption peak confirms the longer conjugation length of PTs. The amorphous nature of the PTs was inferred from the XRD pattern. The PTs prepared with surfactant exhibited different morphology compared to PT prepared without surfactant. The specific capacitances (SC) of the prepared PTs were calculated using cyclic voltammetry technique, the PT prepared with TRITRON X-100 exhibited higher SC of 117 F/g compared to SC of surfactant free PT (78 F/g). Hence, the PTs prepared with surfactants were found to be suitable electrode materials for redox supercapacitors.     

Supercapacitive properties of activated carbon electrode in electrolyte solution with a lithium-modified silica nanosalt

In this work, lithium-modified silica nanosalt (Li202) is solution-synthesized and used as a gel-forming additive in 1.5 M tetraethylammonium tetrafluoroborate (TEABF₄)/acetonitrile (ACN) electrolyte solution for the supercapacitor with activated carbon electrode. The electrochemical properties of the supercapacitor adopting the Li202 (5 wt.%) are investigated using linear sweep voltammetry, cyclic voltammetry, and complex impedance spectroscopy. By the addition of the Li202, the electrochemical stability of the electrolyte is improved over 4.0 V (corresponding to the current density below 0.6 mA cm⁻²) and higher specific capacitances at the scan rates of 10–500 mV s⁻¹ are obtained. Thus, the Li202 can be considered as a promising electrolyte additive to enhance the supercapacitive properties of activated carbon electrode.     

Effect of additives on the structure and electrochemical performance of mesoporous nickel hydroxide

Nickel hydroxide mesoporous structures are synthesized by a simple method in the presence of different additives (oxalic acid, aminoacetic acid, and sulfosalicylic acid). Structural characterizations reveal that the additives can affect the crystal structure, increase the specific surface area, and reduce the pore size of the products. The electrochemical properties of the synthesized Ni(OH)₂ samples are dependent on their crystal phase, surface area, and pore size distribution. Mesoporous β-Ni(OH)₂ with poor crystallinity shows high specific capacitances at different current densities and excellent cycling ability. A highest specific capacitance of 1,693 F?g^?1 can be achieved at a scan rate of 5 mV?s^?1. The results suggest its potential application in electrochemical supercapacitors.     

基于镍泡沫支撑的Co_3O_4纳米多孔结构的高性能超级电容器电极

在众多能量存储和转化器件中,超级电容器由于具有功率密度高、充放电迅速和优异的循环性能的优点而被广泛研究.然而,较低的比容量和能量密度,限制了超级电容作为大尺度能量存储和转化器件的广泛应用.为了提高超级电容器的比容量,需要增大电极材料和电解质的接触面积,进而促进电极材料俘获/释放电解质中的粒子(例如电子、离子或者小分子).在此,我们通过简单的水热法联合高温退火实验方案能够大规模制备出镍泡沫支撑的Co_3O_4多孔纳米结构.无需借助导电胶和粘合剂,在集流器镍泡沫上"生长"Co_3O_4多孔纳米结构直接作为超级电容的电极材料.这种多孔纳米结构和一体化设计思路不仅能够有效提高电极的导电性,而且能够有效缩短离子和电子的迁移路径.由于多孔的结构特征和优异的导电性能,Co_3O_4电极表现出超高比容量(在电流密度为2.5 m A·cm~(-2)和5.5 m A·cm~(-2)时,比容量分别为1.87 F·cm(-2)(936 F·g-1)和1.80 F·cm~(-2)(907 F·g-1))、较好的倍率性能(电流密度从2.5 m A·cm~(-2)增大到100 m A·cm~(-2)时,保留其48.37%的初始电容)和超高的循环稳定性(经历4000次电流密度为10 m A·cm~(-2)的循环充放电过程,保留其92.3%的比容量).这种多孔纳米结构和一体化设计思路对设计其他高性能储能器件具有重要的指导意义.     

The effect of ultrasound upon the oxidation of thiosulphate on stainless steel and platinum electrodes

Ultrasound was found to increase the oxidation peak current and hence the decomposition rate of thiosulphate 50-fold compared to silent conditions. The effects of the ultrasonic frequency (20 and 38 kHz) and power upon the electrochemical oxidation of thiosulphate in aqueous KCl (1 mol dm-3) at stationary stainless steel and platinum electrodes were studied chronoamperometrically and potentiostatically (at various scan rates). No sigmoidal-shaped voltammograms were observed for the redox couple S4O6(2-)/S2O3(2-) in the presence of ultrasound. However, application of ultrasound to this redox couple provided an increase in the oxidation peak current at the frequencies employed, the magnitude of which varied with concentration, scan rate and ultrasonic power. Under sonication at 20 and 38 kHz, the oxidation peak potential shifted anodically with increasing ultrasonic power. This anodic shift in potential may be due to the formation of hydroxyl radicals, changes in electrode surface composition and complex adsorption phenomena. The large increase in oxidation peak currents and the rates of decomposition of thiosulphate, in the presence of ultrasound, are explained in terms of enhanced mass transfer at the electrode due to cavitation and acoustic streaming together with microstreaming coupled with adsorption phenomena. It is also shown that changes in macroscopic temperature throughout the experiment are insufficient to cause the observed enhanced diffusion.     

Structural modification and band gap engineering of sol–gel dip-coated thin films of Zn<Subscript>0.75</Subscript>Mg<Subscript>0.25</Subscript>O alloy under vacuum annealing

In the present study, we investigated the effect of vacuum annealing on the structural and optical properties of sol–gel dip-coated thin films of Zn_0.75Mg_0.25O alloy. XRD studies revealed that all these films were polycrystalline with hexagonal wurtzite structure and there was no trace of additional phases other than ZnO. With increase in annealing temperature, the samples showed preferred orientation along the c-axis, (0 0 2) plane and also peak narrowing and peak shift towards higher angles. The calculated values of mean crystallite size increased with annealing temperature indicating the improvement in crystallinity. Heat treatment caused lattice contraction and a decrease in film thickness. The optical transmittance in the visible spectral range enhanced with increase in annealing temperature while the fundamental absorption edge in the near ultra-violet region got red-shifted with annealing. The calculated values of optical energy gap of the samples showed a decrease with heat treatment due to the improvement in crystallinity during annealing and hence the subsequent decrease in quantum size effect.     

Capacitance extraction method for a gate-induced quantum dot in silicon nanowire metal-oxide-semiconductor field-effect transistors

An improved method of extracting the coupling capacitances of quantum dot structure is reported. This method is based on measuring the charge transfer current in the silicon nanowire metal–oxide–semiconductor field-effect transistor(MOSFET), in which the channel closing and opening are controlled by applying alternating-current biases with a half period phase shift to the dual lower gates. The capacitances around the dot, including fringing capacitances and barrier capacitances, are obtained by analyzing the relation between the transfer current and the applied voltage. This technique could be used to extract the capacitance parameters not only from the bulk silicon devices, but also from the silicon-oninsulator(SOI) MOSFETs.     

采用紫外光照法在磷酸盐玻璃中合成CdS/Ag复合微粒

掺杂有Ⅱ-Ⅵ族半导体纳米颗粒(如CdS)或者过渡金属(如Ag)的玻璃由于其较大的非线性光学效应而引起人们的极大兴趣,而同时掺杂有半导体/金属的复合微粒则可以进一步增强玻璃的三阶非线性效应,因此成为目前的研究热点。我们利用玻璃沉淀技术及随后的热处理和紫外光还原技术制备了含高浓度(1%)Ag微粒的玻璃,并采用X射线衍射分析了其物相,用高分辨扫描电镜分析了其形貌,以及测试了其吸收和发光性能。从CdS/Ag复合微粒的扫描照片可以发现晶粒均匀分布在玻璃中,尺寸约为1μm。X射线衍射发现经过热处理和紫外光照的样品衍射峰中含有CdS和Ag,而只进行热处理的样品则只含有CdS,未处理的样品则显非晶态。CdS/Ag复合微粒的吸收峰呈现典型的表面等离子共振峰(420nm)以及CdS的峰(600nm),只含有CdS微粒的样品的吸收峰则在480nm附近,未处理的样品在320nm附近有一个吸收峰,这可能是由于样品在快速冷却过程中的微小晶化造成的。只含有CdS微粒的样品有三个明显的发光峰,然而CdS/Ag复合微粒的发过峰则消失。我们提出了共振能量转移机制来解释该现象。讨论了紫外光照还原Ag微粒的机制。可以认为通过紫外光照,CdS表面的电子被激发出来还原Ag+,从而形成银颗粒,伴随着空穴则被表面缺陷所捕获。     

Electrochemical determination of ionization constants of tetrabutylammonium salt in acetonitrile and ο-nitrophenyloctylether

Cyclic voltammetry of ferrocene at glassy carbon electrode in acetonitrile (ACN), ο-nitrophenyloctylether (NPOE) and ACN-NPOE mixture with 0.2 M tetrabutylammonium tetrafluoroborate (TBABF₄) were investigated. Both cathodic and anodic peak current were diffusion-controlled at any NPOE fraction. However, the peak current was decreased with the increasing NPOE fraction. In addition, the peak potential difference increased not only with an increase in the NPOE fraction but also in the scan rate, while the values of half-wave potential did not vary largely with the fraction or the scan rate. This indicated that the variation of peak current and peak potential should be due to the variation of the solution resistance. In order to demonstrate this assumption, the conductance of TBABF₄ in ACN, NPOE, and ACN-NPOE mixture were determined by AC impedance. All of the solution conductances were inversely linear to the viscosity of the solvent, which was increased with the fraction of NPOE. The calculated ionization constant of TBABF₄ in ACN was 2.8 times of that in NPOE. TBABF₄ in ACN can work as a supporting electrolyte, whereas they work partly in NPOE.     

CuO纳米粒子的谱学特性研究

以六次甲基四胺为沉淀剂宿主、Cu(NO3)2为铜源在乙醇-水(1∶1,φ)体系中采用均匀沉淀法合成了前驱体Cu2(NO3)(OH)3,然后在不同温度下锻烧获得系列纳米CuO粉体,借助XRD,FTIR,XPS,FT-Raman和UV-Vis等测试手段对其谱学特性进行了系统研究。XRD分析表明,所得粉体为单斜晶系的纳米CuO,随锻烧温度的升高,粉体的粒径增大;XPS图谱表明,随热处理温度的升高CuO粉体的表面氧空位减少,导致表面吸附氧含量降低;FTIR图谱表明,随晶粒粒径的减小,在525cm-1附近处Cu—O键特征吸收峰明显宽化,且发生劈裂,劈裂小峰出现双移现象;FT-Raman谱图表明,随着粒径的减小,样品的拉曼散射峰出现宽化现象,并向低波数方向移动;UV-Vis吸收光谱表明,粉体在300～400nm之间有强的吸收,随着粒径的减小最大吸收发生蓝移。探讨了上述谱学规律的成因,对氧化物纳米粒子的谱学特性研究具有重要的借鉴意义。