铁电极电还原溴化钠甲醇溶液反应动力学和机理

研究溴化钠（NaBr）甲醇溶液在铁电极上电还原反应动力学和机理对于二茂铁电化学制备、非水体系中二氧化碳（CO₂）的电还原和有机电合成等领域具有实际价值和科学意义, 但对此未见详细报道. 本文采用极化曲线和电化学阻抗谱等技术详细地研究了该体系的电还原动力学和机理. 结果表明: 反应物为甲醇而Na⁺只起导电作用; 电极电位是该体系中唯一状态变量, 其对甲醇电还原速率常数的影响符合阿仑尼乌斯唯象方程式; 电还原过程不受扩散极化控制, 溶液欧姆极化是主要极化形式; 甲醇电还原依法拉第定律计量地产生氢气, 反应活化能约为26.2 kJ·mol^-1.     

锂离子在镁电极上的电沉积

研究了熔融氯化锂与氯化钾在摩尔比为58:42的熔盐中,锂在镁电极上的电沉积过程.利用电化学工作站,采用循环伏安法扫描技术,考察了在450℃,扫描速度为20 mV/s时,锂在钼电极和镁电极上的析出电位,得到析出电位分别为-2.4和-2.28 v.结果说明,镁电极对于锂的析出具有诱导作用;发现在所研究的温度范嗣内,电流效率均大于92%;利用扫描电子显微镜考察了镁电极沉积锂前后表面形貌的变化,发现镁电极上沉积锂之后与未沉积锂前相比,表面形成了均匀致密的合金层;扫描电子显微镜能谱分析表明,合金试样中的杂质元素主要为氧,可能是南于样品放置在空气环境中所致,测量时间内引起的.     

从2AlCl3/Et3NHCl离子液体中电沉积制备Ni 和Ni-Al 合金

在含Ni2+的2AlCl3/Et3NHCl离子液体中的铜电极上通过恒电位电沉积制备出金属Ni和Ni-Al合金.采用循环伏安和计时电流方法,揭示铜电极上沉积金属Ni的成核机理,研究了电沉积Ni-Al合金的机理,以及恒电位沉积Ni-Al合金工艺条件对沉积Ni-Al合金表面形貌和电流效率的影响.结果表明:在铜电极上电沉积金属Ni的成核机理为受扩散控制的三维瞬时成核过程.在电量≥3.0 C时,电沉积Ni-Al合金的组成基本不再变化.Ni-Al合金的电沉积机理为,Ni的电沉积受扩散控制,同时进行Al的欠电位沉积,在Ni-Al合金电沉积过程中某些Ni-Al合金相的沉积可能受动力学限制而使Ni-Al合金的组成偏离热力学预测结果.在电沉积Ni-Al合金的沉积电流小且平稳,电沉积速率慢条件下,Ni-Al合金表面形貌致密均一,反之就会出现瘤节.电沉积Ni-Al合金的电流效率＞90％.电沉积物的组成接近于Ni3Al合金.     

Zn(Ⅱ)在锌电极上的电沉积机理

在Zn(Ⅱ)-NH_4Cl准中性体系中,采用循环伏安法(CV)研究了Zn~(2+)在锌电极上的反应方式,通过计时电流法(CA)研究了Zn~(2+)沉积的成核方式,利用交流阻抗谱(EIS)考察了不同过电位时Zn~(2+)沉积的阻抗行为。结果表明:Zn~(2+)的电沉积是一个不可逆电极反应,以两步骤单电子串联的方式进行,第一步为速控步;电极反应的电荷传递系数与锌电极的表面结构有关。在恒电位条件下,体系中锌电极上Zn~(2+)的结晶近似于三维瞬时成核方式。Zn~(2+)的沉积经历了覆盖、吸附成膜、大量晶核形成等过程,该过程随着控制电位的负移由电化学极化过渡到电化学极化-浓差极化混合控制阶段。最后给出了Zn~(2+)在锌电极上电沉积过程的机理。     

镍-碳化钨微粒复合电沉积机理的研究

研究了在普通镀镍溶液中导电性微粒碳化钨与基质金属镍形成复合镀层的电沉积过程，实验结果表明，导电性的ＷＣ微粒在与Ｎｉ共沉积形成Ｎｉ－ＷＣ复合镀层的过程中，也遵循Ｇｕｇｌｉｅｌｍｉ的两步吸附机理，只是在电极表面，ＷＣ微粒的弱吸附覆盖度与强吸附覆盖度的比值，较非导电性微粒的复合共沉积体系的要小得多。     

镍铁异常共沉积研究

本文应用环盘电极并根据环电极上Fe~(2+)离子氧化的极限电量及盘电板上Fe~(2+)离子阴极还原对上述环电极过程的屏蔽效应分别建立两种分解Ni-Fe共沉积极化曲线的方法。应用上述方法研究Hg, Ni, Fe和Ni-Fe等电极上Ni和Fe共沉积的动力学规律。结果表明, Ni~(2+)和Fe~(2+)同时在Hg上电沉积遵循它们单独电沉积的动力学规律, 而在Fe电极上Ni~(2+)电沉积被活化, 在Ni电极上Fe~(2+)电沉积却被阻化。此外, 还讨论Ni-Fe异常共沉积的机理。     

基于铂纳米颗粒电沉积镁铝水滑石修饰电极的电化学葡萄糖生物传感器

采用成核/晶化隔离法合成了镁铝水滑石纳米颗粒,将其修饰到氧化铟锡导电玻璃电极表面;在此修饰电极基础上,利用电沉积还原氯铂酸盐法制备了铂纳米颗粒/水滑石复合修饰电极.由于水滑石层板表面的外限域作用有效抑制了铂纳米颗粒的聚集,使该电极对过氧化氢具有较好的电催化性能.基于镁铝水滑石良好的生物相容性,将葡萄糖氧化酶进一步修饰到该电极表面,实现了对葡萄糖高灵敏的电化学检测,检出限(S/N=3)达1.0μmol/L.     

α-Al2O3与Co-Ni合金电化学共沉积动力学模型

在经典复合电沉积机理基础上,考虑到粒子与电极表面之间的多种作用力,以吸附强度来表征粒子与电极表面的作用力大小,根据粒子在电极表面的临界吸附强度,把粒子的吸附分为有效吸附和非有效吸附.当吸附强度大于临界吸附强度时,粒子能被有效吸附嵌入到沉积层中,粒子被有效吸附的概率和平均吸附强度有关.建立了相应的复合电沉积动力学模型.该模型在α-Al2O3与Co-Ni合金的复合共沉积体系中,在电流密度为1～20 A•dm2范围内得到了验证.通过数学模型和实验结果研究了电流密度对粒子沉积量φc、吸脱附常数K、有效吸附概率P和平均吸附强度的影响规律.     

离子液体中钴的电沉积行为

在含有氯化钴的室温离子液体氯化1-甲基-3-乙基咪唑(EMIC)和乙二醇(EG)体系中研究了金属钴的电沉积. 循环伏安法测试表明, 在EMIC-CoCl2熔盐中, 乙二醇的加入促进了EMIC的解离, 从而使氧化还原电流增大, 在EMIC-CoCl2-EG体系中钴的电沉积是受扩散控制的非可逆电极过程, 在该电解液体系中, Co(II)在Pt电极上的传递系数α为0.30, 扩散系数D0为4.16×10^-6 cm·s^-1; 计时电流法研究表明, 钴在铂电极上的电结晶过程符合三维连续成核的生长机理; 场发射扫描电子显微镜(FE-SEM)观察镀层的微观形貌显示, 金属钴的结晶细小. XRD分析证实, 镀层为纯钴, 沉积的钴是晶态和微晶态的混合物, 并且晶粒尺寸为纳米级.     

α-Al2O3与Co-Ni合金电化学共沉积动力学模型

在经典复合电沉积机理基础上,考虑到粒子与电极表面之间的多种作用力,以吸附强度来表征粒子与电极表面的作用力大小,根据粒子在电极表面的临界吸附强度,把粒子的吸附分为有效吸附和非有效吸附.当吸附强度大于临界吸附强度时,粒子能被有效吸附嵌入到沉积层中,粒子被有效吸附的概率和平均吸附强度有关.建立了相应的复合电沉积动力学模型.该模型在α-Al2O3与Co-Ni合金的复合共沉积体系中,在电流密度为l～20A@dm2范围内得到了验证.通过数学模型和实验结果研究了电流密度对粒子沉积量ψc、吸脱附常数K、有效吸附概率P和平均吸附强度的影响规律.     

Electrodeposition onto magnesium in air and water stable ionic liquids: From corrosion to successful plating

Magnesium is very reactive and therefore magnesium electroplating in aqueous solutions is hazardous. Mg is classified as a water sensitive substrate from the electrodeposition point of view. Therefore, it was suggested that ionic liquids be used as electrolytic solvents for electrodeposition onto Mg and its alloys. Five air and water stable ionic liquids based on choline chloride (ChCl) were investigated to deposit Zn onto several Mg alloys in air. The ChCl/urea mixture was found to be the most feasible liquid for successful electrodeposition. Other liquids produced powdery deposits or resulted in corrosion of Mg substrate. Application of a pulsed current was superior to a constant current in producing smooth, sealed and more corrosion-resistant Zn layers.     

恒电流暂态法研究镁在非水体系的电沉积

恒电流暂态法做为研究金属电沉积的有效工具广泛被采用。传统的恒电流暂态法需要用示波器及照相装置,操作较繁。本文利用Model-273恒电势仪和Apple-Ⅱ微机联用完成了恒电流暂态实验,利用该装置可使操作全部自动化,数据的采集、贮存、打印以及超电势与时间之间关系图的绘制全部由计算机完成,不仅操作简便,且精度高。在验证该装置可靠的基础上,本文用其测定了镁在二甲基甲酰胺中电沉积的动力学参数。不仅加深了对镁     

电沉积工艺对Mg-Ni储氢合金的电化学性能的影响

用电沉积的方法制备了镁 镍储氢合金,探讨了电沉积条件对合金的电化学性能的影响.XRD显示沉积层中含有非晶态Mg Ni相和微晶态Mg相.AAS分析表明沉积合金中Mg的摩尔分数达 8. 57%.合金的放电容量最高为 75. 547mA·h·g-1.     

In situ electrochemical SFG/DFG study of CN⁻ and nitrile adsorption at au from 1-butyl-1-methyl-pyrrolidinium bis(trifluoromethylsulfonyl) amide ionic liquid([BMP][TFSA]) containing 4-{2-[1-(2-cyanoethyl)-1,2,3,4-tetrahydroquinolin-6-yl]diazenyl} benzonitrile (CTDB) and K[Au(CN)₂

In this paper we report an in situ electrochemical Sum-/Difference Frequency Generation (SFG/DFG) spectroscopy investigation of the adsorption of nitrile and CN? from the ionic liquid 1-butyl-1-methyl-pyrrolidinium bis(trifluoromethylsulfonyl) amide ([BMP][TFSA]) containing 4-{2-[1-(2-cyanoethyl)-1,2,3,4-tetrahydroquinolin-6-yl]-diazenyl}benzonitrile (CTDB) at Au electrodes in the absence and in the presence of the Au-electrodeposition process from K[Au(CN)?]. The adsorption of nitrile and its coadsorption with CN? resulting either from the cathodic decomposition of the dye or from ligand release from the Au(I) cyanocomplex yield potential-dependent single or double SFG bands in the range 2,125-2,140 cm?1, exhibiting Stark tuning values of ca. 3 and 1 cm?1 V?1 in the absence and presence of electrodeposition, respectively. The low Stark tuning found during electrodeposition correlates with the cathodic inhibiting effect of CTDB, giving rise to its levelling properties. The essential insensitivity of the other DFG parameters to the electrodeposition process is due to the growth of smooth Au.     

二甲基甲酰胺中Y-Mg-Co合金膜的电化学制备

研究了二甲基甲酰胺（DMF）中Y(Ⅲ) 和Mg(Ⅱ) 及Co(Ⅱ)在Pt电极上的电化学行为.结果表明,Y(Ⅲ)、Mg(Ⅱ)及Co(Ⅱ)在Pt电极上一步不可逆还原为Y(0)、Co(0)和Mg(0).在301 K时,利用循环伏安法分别测定出Mg(ClO4)2-LiClO4-DMF中Mg(Ⅱ)的扩散系数和传递系数为2.95×10－6 cm2•s－1和0.11；CoCl2-LiClO4-DMF中Co(Ⅱ)的扩散系数和传递系数为1.34×10－5 cm2•s－1和0.24；Y(NO3)3-LiClO4-DMF中Y(Ⅲ)的扩散系数和传递系数为1.68×10－5 cm2•s－1和0.10.在铜电极上于－1.50～－3.00 V(vs SCE)下恒电位电沉积,得到黑色、光滑致密、粘附性好的Y-Mg-Co合金膜,其中Y含量为3.88％～58.66％;Mg含量为4.51％～17.52％.     

Electrodeposition of gold particles on aluminum substrates containing copper

Electrodeposition of adhesive metal films on aluminum is traditionally preceded by the zincate process, which activates the aluminum surface. This paper presents an alternative approach for activation of aluminum by using films containing 99.5% aluminum and 0.5% copper. Aluminum/copper films are made amenable for subsequent electrodeposition by anodization followed by chemical etching of aluminum oxide. The electrodeposition of gold is monitored with electrochemical impedance spectroscopy (EIS). Analysis of EIS data suggests that electrodeposition of gold increases the interfacial capacitance from values typical for electrodes with thin oxide layers to values typical for metal electrodes. Scanning electron microscopy examination of aluminum/copper films following gold electrodeposition shows the presence of gold particles with densities of 10(5)-10(7) particles cm(-2). The relative standard deviation of mean particle diameters is approximately 25%. Evaluation of the micrographs suggests that the electrodeposition occurs by instantaneous nucleation followed by growth of three-dimensional semispherical particles. The gold particles, which are electrically connected to the conductive aluminum/copper film, support a reversible faradaic process for a soluble redox couple. The deposited gold particles are suitable for subsequent metallization of aluminum and fabrication of particle-type films with interesting catalytic, electrical, and optical properties.     

Hybrid Bioceramic Coatings of Calcium Phosphate Prepared by Electrodeposition Technique

The electrodeposition of bioceramic coatings of calcium phosphates on metal substrate is a newly developed method for preparing implanted bio-medical devices^[1-2]. It is proposed to have a remarkable higher bioactivity and excellent bio-capability for the electrodeposited bioceramic coating, because it may produce a pure structure and composition of hydraxiapatite (HAP) during electrodeposition process at room temperature. However, the bonding force of electrodeposition bioceramic coating to the metal substrate is too weak. It has become a major problem in developing electrodeposition technique for preparing bioceramic coatings of calcium phosphates on metal substrate. The present work has been emphasized to develop an approach for preparing HAP bioceramic coatings, which has strong bonding force both in the bulk phase of HAP coating and to the metal substrate.     

Effect of supporting electrolyte concentration on one-step electrodeposited CuInS2 films for ZnS/CuInS2 solar cell applications

Journal of Solid State Electrochemistry - A one-step electrodeposition process was used to obtain CuInS2 (CIS) films on a molybdenum substrate by varying the supporting electrolyte (lithium...     

Mg/Na selectivity of sulfonic cation-exchange membrane modified with poly(4-vinyl-N-propylpyridinium) bromide

Mg/Na selectivity of sulfonic cation-exchange membrane modified with poly(4-vinyl-N-propylpyridinium) bromide by surface electrodeposition, influenced by the electrodialysis conditions, is studied.     

铅在铜上电沉积的原位椭圆偏振法

采用循环伏安法(CV)和原位椭圆偏振法(SE)研究铅在铜电极上的电沉积行为。 原位椭圆偏振参数Ψ和Δ值的变化率在CV图峰电位处同时出现极值。 通过建立单层膜模型描述“电极-溶液”界面的结构并对椭圆偏振光谱数据进行拟合得到铅沉积层厚度随电位的变化规律。 拟合结果显示,铅在铜电极上的电沉积有3个不同的沉积速率,-0.20～-0.35 V之间沉积速率为0.003 nm/mV,-0.35～-0.48 V之间沉积速率为0.025 nm/mV,-0.48～-0.60 V之间沉积速率为0.116 nm/mV,由此表明铅的电沉积分为3个不同阶段：欠电位沉积阶段、欠电位沉积向本体沉积的过渡阶段和本体沉积阶段。