氨络合物体系中镍在玻璃碳上的电化学成核机理

采用循环伏安法和计时电流法研究了氨络合物体系中镍在玻璃碳上电结晶的初期行为。结果表明．镍在该基体上的沉积没有经历UPD过程，镍的电沉积经历了晶核形成过程，在所研究的外加电位范围内其电结晶按连续成核和三维生长方式进行，外加电位对晶体生长具有显著的影响。通过分析恒电位暂态曲线，求出镍离子的扩散系数D，以及不同外加电位下的饱和晶核数密度Nsat，探讨了外加电位对成核作用的影响。     

钯铁合金共沉积行为及其成核机理的研究

应用循环伏安法和电位阶跃法研究了Pd-Fe合金电沉积的循环伏安特性与电结晶机理.结果表明,在以FeSO4·7H2O和Pd(NH3)2Cl2为主盐、磺基水杨酸(SSCS)为络合剂、(NH4)2SO4为导电盐所组成的镀液体系中,Pd-Fe合金共沉积经历了成核过程,而不是欠电位沉积,且其电沉积反应是一个不可逆过程;将Pd-Fe合金共沉积的恒电位暂态曲线进行拟合得知,其电结晶的成核过程属于三维瞬时成核方式.     

碱性锌酸盐镀锌中锌的电化学成核机理

过去对碱性锌酸盐镀锌电化学成核机理的研究较少。为此,采用循环伏安法和计时电流法研究了碱性锌酸盐体系中锌在玻碳电板上的电化学成核机理。结果表明：锌在玻碳电极上的电沉积没有经历欠电位沉积过程,而是经历了晶核形成过程,按三维瞬时成核生长方式进行;锌配离子的平均扩散系数D为4．27×10^-6cm^2／s,晶体生长速率和晶核数...     

添加剂对氯化钾溶液中锌电沉积的影响

目前,添加剂对镀锌的作用及其机理说法不同.用线性扫描法、循环伏安法和计时电流法分别研究了聚乙二醇400(PEG400)及其与苄叉丙酮(BA)复配在氯化钾(KCl)溶液中对锌电沉积的影响;根据Scharifker-Hills成核模型拟合了电流-时间数据.结果表明:PEG400和BA混合比单加更能增大锌在KCl溶液中电沉积的过电位,能更有效地抑制析氢反应;锌的电沉积机理在一定程度上取决于所加入的添加剂,仅添加PEG400,锌电沉积机理与无添加剂的一样,都是晶核瞬时形成和成长的过程,PEG400和BA同时加入,锌的电沉积机理是晶核连续形成后转为晶核瞬时形成.本研究结果有助于氯化钾镀锌高效添加剂的开发.     

聚乙烯亚胺添加剂对硫代硫酸盐体系银电沉积行为的影响

银的电结晶过程直接影响银镀层的性能,但目前很少关注聚乙烯亚胺(PEI)对银电沉积过程的影响。采用循环伏安、计时电流及交流阻抗技术研究了硫代硫酸盐体系中添加PEI前后银电沉积的电化学行为,结合扫描电镜分析了银的电结晶方式。结果表明:PEI对银在硫代硫酸盐体系中的电沉积有阻化作用,添加0.08 g/L PEI可使反应电阻由176.3Ω·cm2增至427.1Ω·cm2;加入PEI不改变银的电结晶形核机理,银仍按三维连续成核方式生长,PEI能提高银电结晶成核速度,但会抑制晶体向外生长。     

ChCl/CrCl3·6H2O体系中Cr(Ⅲ)的电化学成核机理

本文在ChCl/CrCl3.6H2O离子溶液体系中,采用循环伏安法和恒电位阶跃法研究了Cr(Ⅲ)在玻碳电极上的电化学成核机理。研究结果表明,Cr(Ⅲ)的电化学成核机理是三维成核并与过电位有关。当过电位较小时,Cr(Ⅲ)的电结晶过程为三维连续成核,其扩散系数为(2.56±0.33)×10-11m2/s。当过电位较大时,Cr(Ⅲ)的电结晶过程趋向于三维瞬时成核过程,其扩散系数和晶核数密度均与过电位无关,分别为(3.04±0.3)×10-11m2/s和(4.47±0.05)×1011/m2。两种成核方式的法向生长速率常数均与过电位成线性关系,晶体法向的生长没有受到任何阻滞。     

酸性镀镍中有机添加剂对镍电沉积的作用机理

为了进一步弄清常用镀镍添加剂邻磺酰苯酰亚胺、1,4-丁炔二醇及2者的混合物对酸性镀镍中镍电沉积的作用机理,通过循环伏安、交流阻抗和电势阶跃等电化学方法进行了试验研究.结果表明:加入有机添加剂后均能使镍电沉积电位负移,且该电极过程不可逆;同时镍沉积过程经历了2个电子转移步骤和中间产物吸附步骤;当2种添加剂联合使用时,镍电沉积的阴极过电位增大约650 mV,并能有效增大成核数密度,更有利于得到光亮镍层;加入有机添加剂后镍电沉积,I2/Im2-t/tm曲线均靠近瞬时成核理论曲线,说明在有机添加剂作用下镍的沉积遵循瞬时成核三维生长的电结晶机理.     

电沉积与铁基体电位活化的增强拉曼光谱研究

为探讨电沉积初始过程对电镀层结合强度的影响,采用循环伏安法和表面增强拉曼(SERS)光谱研究了光亮铁电极在5%KCl溶液中表面氧化物随电位负移的还原过程,并应用循环伏安法和恒电流电位-时间法研究了氰化物镀铜体系铁基体的电位活化现象和电沉积初始过程.结果表明,在电位-0.9 V时,特征波数为424 cm-1和499 cm-1的Fe3O4谱峰消失,电位-1.2 V时,特征波数671 cm-1的FeO、谱峰明显降低,说明Fe3O4和FeO在不同电位下依次实现还原过程.循环伏安曲线在-0.9 V及-1.2 V附近也依次出现了铁氧化物的还原电流平阶.在氰化物镀液中,铜的析出电位(约-1.4 V)负于铁表面氧化物的还原电位,电极过程首先实现铁表面氧化物的还原,随后铜沉积在活化的铁基体上.     

硫酸型镀铟电极过程动力学初探

过去用电化学方法对硫酸型镀铟工艺、作用机理研究较少.采用循环伏安、线性电位扫描和交流阻抗等电化学方法,研究了硫酸型镀铟中的阴极反应机理.结果表明:该体系内铟电沉积的最佳pH值为2～3,最佳温度为35～45℃;该阴极过程中存在前置化学反应和随后两个不可逆电化学反应,其中第一个电化学反应是控制步骤,其阴极过程电极反应标准常数为8.188×10-10cm/s.     

Cu-In合金硒化法制备CuInSe_2薄膜

采用三电极体系恒电压电沉积法制备了Cu-In薄膜,经硒化退火生成CuInSe_2薄膜.采用循环伏安法研究了电沉积Cu-In的循环伏安特性,确定其最佳沉积电位在-0.75V左右,Cu与In的化学计量比为1.1,达到了理想前驱体的Cu与In的化学计量比.研究了不同沉积电位下材料组成、结构与性能的影响.硒化后,Cu与In的化学计量比为1,1时形成了比较单一的CuInSe_2黄铜矿相结构.     

Preparation of PtSn/C and PtSnNi/C electrocatalysts using the alcohol-reduction process

PtSn/C electrocatalyst with Pt:Sn molar ratio of 50:50 and PtSnNi/C electrocatalyst with a Pt:Sn:Ni molar ratio of 50:40:10 were prepared by the alcohol-reduction process using ethylene glycol as solvent and reducing agent. The electrocatalysts were characterized by EDX, XRD, TEM and cyclic voltammetry. The electro-oxidation of ethylene glycol was studied by cyclic voltammetry and chronoamperometry using the thin porous coating technique. PtSnNi/C electrocatalyst showed a superior performance compared to PtSn/C electrocatalysts in the potential range of interest for direct ethylene glycol fuel cell.     

Response times of carbon fiber microelectrodes to dynamic changes in catecholamine concentration

The electrode response time and the measured concentrations during dynamic catecholamine changes were compared using constant potential amperometry and fast-scan cyclic voltammetry. The amperometric response to a rectangular pulse of catecholamine is more rectangular than the cyclic voltammetric response; however, the response times are very similar when, during cyclic voltammetry, the temporal lag due to adsorption and desorption of catecholamine to the electrode is removed by deconvolution. Deconvolution of cyclic voltammetry data was applied to stimulated dopamine release in vivo, allowing for modeling of release and uptake kinetics and to measure catecholamine release from single cells, resulting in better resolution of peaks from single vesicles. In vitro postcalibrations were performed to calculate concentrations of catecholamine measured with cyclic voltammetry and amperometry. The addition of 600 microM ascorbic acid to the postcalibration buffer, allowing a catalytic reaction to regenerate dopamine, resulted in similar calculated concentrations for stimulated release of dopamine using amperometry and cyclic voltammetry. Using deconvoluted cyclic voltammetry to remove the response time lag and adding ascorbic acid to the calibration buffer, the shape and concentration of dynamic catecholamine changes are very similar when measured with constant potential amperometry and cyclic voltammetry.     

Specific features of oxygen electroreduction on platinized carbon black-functionalized carbon nanotube composite

The electrochemical behavior of multiwalled carbon nanotubes (MWCNTs) containing functional surface groups has been studied by the methods of cyclic voltammetry and direct-current polarography with stationary and rotating disk electrodes. The surface catalytic activity of supported platinum in the reaction of molecular oxygen electroreduction and the influence of functionalized MWCNTs on this process were determined.     

Electrochemical and analytical investigation of passive films formed on stainless steels in alkaline media

Passive films were grown in potentiodynamic mode, by cyclic voltammetry on AISI 316 and AISI 304 stainless steels. The composition of these films was investigated by X-ray photoelectron spectroscopy (XPS). The electrochemical behaviour and the chemical composition of the passive films formed by cyclic voltammetry were compared to those of films grown under natural conditions (by immersion at open circuit potential, OCP) in alkaline solutions simulating concrete. The study included the effect of pH of the electrolyte and the effect of the presence of chloride ions.The XPS results revealed important changes in the passive film composition, which becomes enriched in chromium and depleted in magnetite as the pH decreases. On the other hand, the presence of chlorides promotes a more oxidised passive layer. The XPS results also showed relevant differences on the composition of the oxide layers for the films formed under cyclic voltammetry and/or under OCP.     

Electrochemical characterization of Pt-Ru-Pd catalysts for methanol oxidation reaction in direct methanol fuel cells

PtRuPd nanoparticles on carbon black were prepared and characterized as electrocatalysts for methanol oxidation reaction in direct methanol fuel cells. Nano-sized Pd (2-4 nm) particles were deposited on Pt/C and PtRu/C (commercial products) by a simple chemical reduction process. The structural and physical information of the PtRuPd/C were confirmed by TEM and XRD, and their electrocatalytic activities were measured by cyclic voltammetry and linear sweep voltammetry. The catalysts containing Pd showed higher electrocatalytic activity for methanol oxidation reaction than the other catalysts. This might be attributed to an increase in the electrochemical surface area of Pt, which is caused by the addition of Pd; this results in increased catalyst utilization.     

有机体系中聚苯胺电化学性能研究

有机体系中，采用循环伏安法（CV）在铂片表面电聚合制备聚苯胺，并通过循环伏安、恒流充放电测试了聚苯胺的电化学特性，结果表明：聚苯胺电极的循环伏安曲线呈现矩形特征，恒流充放电的电压和时间关系为线性关系。说明该电极具有典型的电容行为，其比电容高达320．8F／g。CV循环500圈后比电容基本没有变化，电极的循环寿命较高。     

PAn-TiO2复合膜的制备与表征

采用电化学循环伏安法,以不锈钢片为墓底,在添加适量二氧化钛纳米粒子的笨胺和硫酸溶液中实现了PAn-TiO2 复合膜的电聚合.通过循环伏安法(CV),X射线衍射图语(XRD)、差热分析曲线(DSC)对复合膜的电化学特性和组成进行了研究与表征.结果表明,TiO2 与聚苯胺之间实现了结构上的复合,TiO2的引入提高了聚苯胺膜...     

铈元素对镍电极性能的影响

研究了Ce元素作为添加剂，通过外掺和共沉积的方式加到Ni(OH)2时对镍电极性能的影响，并用循环伏安法对结果进行分析，结果表明外掺法极大地提高了电极的性能，而共沉积加入Ce元素却不能有效地改善电极的性能，循环伏安实验结果表明，外掺法加入Ce元素时能够很好地改善电极的可逆性，改善了电极反应中电子的传输能力，因而很好地改善了电极的性能。     

锌蒙脱石的电化学特性

本文把液体电化学的循环伏安法移植到固态体系。研究了锌蒙脱石固体电解质在 Pt 电极上的电化学行为,取得了较为满意的结果。阐明锌蒙脱石是一种以 Zn~(2+)离子导电为主的 Zn~(2+)、H~+混合阳离子导电的固体电解质。这些阳离子的电极过程随循环次数和扫描速率而变。研究了电极反应动力学的控制步骤。对实验结果进行了讨论和解释。