Electrochemical Behavior of Copper in CuCI2 Silica Sol and Aqueous Solutions

采用循环伏安法和计时安培法研究了CuCl2硅溶胶和水溶液中铜在玻碳电极上的电沉积和电结晶行为．结果表明在两种CuCl2电解质中，铜的电沉积分两个步骤完成，Cu^2＋还原为Cu^＋在硅溶胶中较水溶液中容易；采用吸附一成核模型解析电流一时间暂态曲线，并确定铜的电结晶机理为扩散控制下的连续成核三维生长（3DP），Cu^2＋在水溶液中的扩散系数较硅溶胶中的大，但相同电位下在硅溶胶中的饱和成核数密度高于水溶液中．     

CO32-对羟基乙叉二膦酸体系铜电结晶的影响

采用循环伏安和计时安培法研究了羟基乙叉二膦酸(HEDPA)镀铜液中铜在玻碳电极上电结晶的初期行为。结果表明：羟基乙叉二膦酸(HEDPA)镀铜体系中,铜的电沉积过程经历了晶核形成过程;当溶液中不含CO32-时,其电结晶按连续三维成核方式进行,而CO32-的加入,使得铜电结晶按瞬时三维成核方式进行;成核数密度都随着电位的提高而增加。这可能是CO32- -以第二配体形式进入HEDPA和Cu2+构成的络合结构,从而形成更稳定的络合物吸附在电极表面所致。     

CO2-3对羟基乙叉二膦酸体系铜电结晶的影响

采用循环伏安和计时安培法研究了羟基乙叉膦酸(HEDPA)镀铜液中铜在玻碳电极上电结晶的初期行为.结果表明:羟基乙叉二膦酸(HEDPA)镀铜体系中,铜的电沉积过程经历了晶核形成过程;当溶液中不含CO32-时,其电结晶按连续三维成核方式进行,而随着CO32-的逐渐加入,使得铜电结晶按瞬时三维成核方式过渡;成核数密度都随着电位的提高而增加.这可能是CO32-以第二配体形式进入HEDPA和CU2+构成的络合结构,从而形成更稳定的络合物吸附在电极表面所致.     

一步法电化学沉积Cu(In1-x,Gax)Se2薄膜的特性

在CuCl2、InCl3、GaCl3及H2SeO3组成的酸性水溶液电沉积体系中, 对Mo/玻璃衬底上一步法电沉积Cu(In1-x, Gax)Se2(简写为CIGS)薄膜进行了研究. 为了稳定溶液的化学性质, 在溶液中加入邻苯二甲酸氢钾和氨基磺酸作为pH缓冲剂, 将溶液的pH值控制在约2.5, 并提高薄膜中Ga的含量. 通过大量实验优化了溶液组成及电沉积条件, 得到接近化学计量比贫Cu 的CIGS薄膜(当Cu与In+Ga的摩尔比为1时, 称为符合化学计量比的CIGS薄膜; 当其比值为0.8-1时, 称为贫Cu或富In的CIGS 薄膜)预置层, 薄膜表面光亮、致密、无裂纹. 利用循环伏安法初步研究了一步法电沉积CIGS薄膜的反应机理, 在沉积过程中, Se4+离子先还原生成单质Se, 再诱导Cu2+、Ga3+和In3+发生共沉积. 电沉积CIGS薄膜预置层在固态硒源280 ℃蒸发的硒气氛中进行硒化再结晶, 有效改善了薄膜的结晶结构, 且成份基本不发生变化,但是表面会产生大量的裂纹.     

氯离子对铜在玻碳电极上电结晶的影响

采用线性扫描伏安法和计时安培法研究了硫酸铜溶液中铜在玻碳电极上电结晶 的初期行为。在含与不含氯离子的0.05mol·L~(-1) cUso_4-0.5 mol·L~(-1) H_2SO_4电解液中,循环伏安实验结果表明铜在玻碳基体上的沉积没有经过UPD过 程;氯离子明显使Cu的沉积和氧化峰变得尖锐,促进Cu的沉积速度。计时安培实验 结果表明,Cu的电结晶按瞬时成核和三维生长方式进行。氯离子不改变Cu的结晶机 理,但在I～t曲线中,导致电流达最大(I_m)所需的时间t_m减小、晶核数密度和生 长速度增大,从而明显改变Cu沉积层的质量。当Cl~-浓度在10～20mg·L~(-1)范围 内,成核的晶核数密度达较大,即氯离子的最适宜添加量。     

添加剂3-巯基-1-丙烷磺酸钠对铜电沉积影响的研究

采用循环伏安(CV)、线性电位扫描(LSV)、计时安培(CA)和交流阻抗(AC impedance)电化学方法结合扫描电镜(SEM)研究了不同浓度的3-巯基-1-丙烷磺酸钠(MPS)对CuSO₄-H₂SO₄体系中铜在玻碳电极(GCE)上的电沉积过程的影响. CV, LSV和AC impedance实验结果一致表明 MPS阻化铜的电沉积, 并且随着MPS浓度的增加, 其阻化作用增强. 但是MPS对Cu的电结晶过程表现为促进作用, CA与SEM研究结果一致表明, MPS不改变Cu的电结晶成核机理, 仍然按瞬时成核和三维生长方式进行, 并且成核数目随着MPS浓度的增大而增加.     

铜电极表面铜锡合金电结晶机理

在弱酸性柠檬酸盐体系铜锡合金镀液中,采用线性扫描伏安(LSV)、循环伏安(CV)和计时安培实验方法,运用Scharifker-Hills(SH)理论模型和Heerman-Tarallo(HT)理论模型分析拟合实验结果,研究铜锡合金在铜电极上的电沉积过程与电结晶机理.结果表明,铜锡合金在铜电极表面实现共沉积并遵循扩散控制下三维瞬时成核的电结晶过程.电位阶跃从-0.80 V负移至-0.85 V(vs SCE),HT理论分析得到铜锡合金的成核与生长的动力学参数分别为成核速率常数(A)值从20.19 s-1增加至177.67 s-1,成核活性位点密度数(N0)从6.10×105cm-2提高至1.42×106cm-2,扩散系数(D)为(6.13±0.62)×10-6cm2s-1.     

纳米Al_2O_3颗粒对镍电结晶过程的影响

借助循环伏安(CV)和计时安培(CA)研究了在不同电位下,纳米Al2O3微粒对镍由硫酸盐混合溶液在铜基底上电结晶沉积的影响.结果表明,Ni-Al2O3镀液体系电沉积的起始电位约为-740 mV.随着阶跃电位负移,Ni-Al2O3镀液体系电沉积成核时间tm逐渐缩短.与纯Ni镀液体系电沉积的tm相比,在-740~-830mV较低阶跃电位下,Ni-Al2O3镀液体系电沉积的成核时间tm明显缩短,表明Al2O3微粒有助于镍的电结晶成核.在-890 mV阶跃电位下,Ni-Al2O3镀液体系电沉积初始阶段的成核过程满足Scharifker-Hills三维瞬时成核模型.     

玻碳电极上铜电沉积初期行为研究

运用循环伏安和计时安培法研究酸性镀铜溶液中硫酸和 2_巯基苯骈咪唑对铜电沉积初期行为的影响 .实验表明铜的电沉积经历了晶核形成过程 ,其电结晶按瞬时成核三维生长方式进行 ,硫酸对铜的电沉积具有加速作用 ,而 2_巯基苯骈咪唑对铜的电沉积起阻化作用 ,两者均不改变铜的电结晶机理     

烟酸对酸性硫酸盐体系铜电沉积的影响

对溶液A: 0.8 mol•L－1硫酸铜,0.6 mol•L－1硫酸,5.0×10－5 mol•L－1氯离子,1.0×10－4 mol•L－1聚乙二醇的溶液,溶液B:在溶液A中加入2.0×10－2 mol•L－1烟酸,pH为0.5,运用循环伏安和计时安培法研究玻碳电极上铜的电沉积行为.结果表明,铜的电沉积过程经历了晶核形成过程,其电结晶按瞬时成核和三维生长方式进行.烟酸的加入对铜的电沉积具有阻化作用,但不改变铜的电结晶机理.沉积层的X射线衍射表明Cu为面心立方结构,在烟酸存在下沉积层出现(220)高择优取向,这可能是烟酸在Cu(220)晶面上发生强烈吸附作用的结果.     

Electrocrystallizations of copper on glassy carbon in CuCl2 silica sol and aqueous solutions

Electrocrystallizations of copper from both CuCl₂ silica sol and aqueous solutions were studied by the chronoamperometry technique.It was found that current density contributions of the double-layer charging（iDL） in current-time transients（CTTs） from both of the solutions were large.An adsorption-nucleation based model was proposed to analyze quantitatively the CTTs,by which copper electrocrystallization mechanism was characterized as progressive nucleation with 3D growth（3DP） under diffusion control.The diffusion coefficient of copper ions and the AN_∞products in aqueous solutions were larger than that in silica sols, which indicated that copper nucleation was inhibited in sol solution.The large iDL may be resulted from the adsorption of chloride ions on the electrode surface.     

高序石墨电极上单分散纳米铜粒子的电结

Mechanism of copper electrocrystallization on highly oriented pyrolytic graphite electrode from a solution of 1 mmol/L CuSO4 and 1.0 mol/L H2SO4 has been studied using cyclic voltammogram and chronoamperometry. The results show that in copper electrodeposition the charge-transfer step is fast and the rate of growth is controlled by the rate of mass transfer of copper ions to the growing centers. Reduction of Cu(Ⅱ) ions did not undergo underpotential deposition. The initial deposition kinetics of Cu electrocrystallization corresponds to a model including progressive nucleation and diffusion controlled growth. Copper nanocrystals with size of 75.6 nm and relative standard deviation of 9% can be obtained by modulation potential electrodeposition.     

PEG-Cl－添加剂存在下的铜电结晶过程研究

用线性电位扫描、循环伏安和计时安培电化学方法研究了聚乙二醇(PEG)和Cl^－同时存在时, 酸性镀铜溶液中Cu在玻碳电极(GCE)上的电结晶过程. 研究表明, PEG-Cl^－作用下Cu 的电结晶按瞬时成核和三维生长方式进行. PEG-Cl^－使电极表面的活性点急剧减少, 并降低了Cu^2＋的扩散系数, 阻化了Cu的电沉积和成核过程. PEG-Cl^－作用时, Cl^－离子仍然表现出较强的促进作用, 随Cl^－浓度的增大, Cu^2＋的扩散系数、Cu的沉积速度和成核速度都有所提高. 适宜的PEG, Cl^－浓度使成核数密度增大.     

乙二胺硅胶材料对铜和锌离子的动态吸附

合成了胺基含量为1.35 mmol/g的乙二胺硅胶材料(EDA/SiO2),研究了EDA/SiO2对Cu2+和Zn2+的动态吸附及动态竞争吸附。结果表明,铜溶液流量和初始浓度对材料动态吸附性能有显著影响,随着溶液初始浓度的增大、流速的加快,穿透时间明显缩短。动态吸附实验结果符合Thomas模型,计算结果显示,铜溶液初始浓度由1.99 mmol/L增大至10.00 mmol/L时,模型平衡吸附容量q0从0.272 mmol/g增大至0.476 mmol/g,影响显著;流量对q0影响不显著。溶液流量和初始浓度对吸附速率常数kTh均有影响,随溶液流量增大、初始浓度的降低,速率常数值增大。在单一体系中,EDA/SiO2对Cu2+和Zn2+的工作吸附量分别为0.340和0.127 mmol/g,混合体系的吸附量均小于单一体系中的吸附量,并且对Zn2+的吸附量下降显著,表明EDA/SiO2对Cu2+的吸附能力强于Zn2+。6次循环实验表明,盐酸和氨水可对EDA/SiO2材料实现再生,再生后材料对铜的吸附容量和穿透时间的下降幅度不大,可重复使用。     

Cu-Fe基双孔载体催化剂结构和低碳醇合成反应性能

采用超声浸渍法制备了Cu、Fe 双活性组元改性的双孔载体(M)催化剂, 采用N₂物理吸附、H₂程序升温 还原/脱附(H₂-TPR/TPD)、X射线衍射(XRD)等表征手段考察了催化剂中Cu-Fe的相互作用, 并在固定床反应器 中评价了Cu/Fe摩尔比的改变对低碳醇合成反应性能的影响. 结果表明: 小孔硅溶胶浸渍在大孔硅凝胶中可形 成具有不同纳米孔径结构的双孔载体, 增加小孔硅溶胶的含量可促使双孔载体中小孔纳米结构尺寸变小. Fe/ Cu摩尔比的增加有利于铜物种在载体表面的分散, 促进了表层CuO和Fe₂O₃的还原, 加强了双孔载体内孔道 与铜铁氧化物之间的相互作用, 促使了单质铜的分散和铁碳化物的生成. CO加氢反应活性和低碳醇时空收率 随着Fe/Cu 摩尔比的逐渐增加呈现增加的变化趋势. 当Fe/Cu 摩尔比增加到30/20 时, Cu-Fe 基双孔载体催化 剂的CO转化率增加到46%, 低碳醇的时空收率增加到0.21 g·mL^-1·h^-1, C₂₊OH/CH₃OH质量比达到1.96.     

Transformation of Structure and Properties of Vesicles Induced by Transition Metal Ions

This paper proved that octodecyl propylenediamine could form vesicles in pure water and aqueous solution of CuCl2 or Cu（NO3）2. The structure and morphology of vesicles were different when the copper （Ⅱ） salt was added to the solution. The results showed that both the counterions and the ligands had strong influence on the configuration of coordinated structures and packing model in bilayer membrane of vesicles.     

Copper Crystallization from Aqueous Solution: Initiation and Evolution of the Polynuclear Clusters

The initial steps of copper electrocrystallization process from aqueous solutions have been studied at DFT level of theory. It has been shown that Cu(H₂O) unit is the final product of Cu²⁺-ions electroreduction. From this particle clusters Cu_n·aq are formed and grow. Aggregation of copper atoms to the Cu_n·aq clusters consists of two steps. The first step includes condensation of Cu(H₂O) units to hydrated clusters Cu_n(H₂O)_n (n = 2–6). At the second step bonding of Cu(H₂O) particles is accompanied by dehydration of clusters yielding Cu_n(H₂O)_m structures (n > m). Cluster Cu₇·aq has been singled out as key structure based on calculated values of energies and Cu–Cu bond distances of Cu_n·aq clusters. This cluster is of D_5h symmetry which is typical for copper microcrystals formed from aqueous solutions in electrocrystallization processes on foreign surface. This key particle could be considered as a critical nucleus. Number of copper atoms therein matches average dimension of critical nucleus.     

Correlation between gelation time, structure and texture of low-doped silica gels

It is shown how the properties of a porous silica xerogel prepared using a classical sol-gel synthesis can be fine-tuned by a minor modification of the composition. The addition of a doping cation (Cu(2+), Ca(2+), Na(+)) in trace quantities in the silica sol was found to exert a dramatic effect at all stages of material preparation. An investigation of both liquid and solid phases is presented, making it possible to highlight strong correlations. The time-resolved speciation of Si-containing moieties in the sol was found to be an indication of the structuration of the gel, which was reflected by the porosity and by the molecular structure of the resulting porous material. Based on a careful comparison of several slightly doped silica gels, a model is proposed which makes it possible to predict the structure and the texture of a silica gel from data recorded early in the liquid phase.     

Preparation and characterization of polypyrrole-silica colloidal nanocomposites in water-methanol mixtures

The effect of methanol cosolvent on the synthesis of polypyrrole-silica colloidal nanocomposites using ultrafine silica sols in combination with both FeCl3 and APS oxidants has been investigated. Two protocols were evaluated: the addition of methanol to an aqueous silica sol and the addition of water to a methanolic silica sol. The latter protocol proved to be more robust, since it allowed colloidally stable dispersions to be prepared at higher methanol content (up to 50 vol% using the APS oxidant). This allowed greater control over the particle size of the nanocomposite particles. In general, the spectroscopic data, the particle size range, silica contents and electrical conductivities of these nanocomposites were similar to those reported earlier for purely aqueous formulations. Polypyrrole contents ranged from 49 to 71% by mass and particle diameters varied from around 160 to 360 nm. In terms of colloid stability, the APS oxidant was preferred for nanocomposite syntheses in the presence of methanol. However, the FeCl3 oxidant generally gave higher conductivities and narrower size distributions under comparable conditions. HF etching experiments combined with transmission electron microscopy studies indicated that, to a first approximation, these nanocomposite particles had core-shell morphologies, with a hydrophobic polypyrrole core and a hydrophilic silica shell that compose approximately one monolayer of silica sol particles. Finally, aqueous electrophoresis measurements suggested that the polypyrrole-silica nanocomposites were silica-rich and that the methanolic silica sol was more hydrophobic (lower surface charge density) than the aqueous silica sol.