Cl~-对Zn-Co(Fe)合金共沉积中Zn转移电流密度的影响

在氯化物电解液中的Zn-Co, Zn-Fe合金共沉积,存在着由正常共沉积转变成异 常共沉积的Zn的转移电流密度,该值随着Cl~-浓度的增加而增加,当Cl~-浓度高达 4 mol·dm~(-3)以上时,Zn-Fe合金共沉积中已不存在Zn的转移电流密度,为单一 正常共沉积。这是因为Cl~-降低了Co,特别是Fe的析出过电位之故。     

Cl-对Zn-Ni合金共沉积Zn转移电流密度的影响

在氯化物电解液中Zn_Ni合金共沉积存在着由正常共沉积转变成异常共沉积的Zn转移电流密度 ,该转移电流密度随着Cl-浓度的增加而增加 ,而与溶液pH值基本无关 .这是由于Cl-的存在降低了Ni的析出过电位 ,并对Ni的析出有催化作用之故     

常温下从离子液体电解液中电沉积金属钴

研究了离子液体镀液中Co、Zn的共沉积行为。ZnCl2-EMIC -CoCl2电解液的循环伏安曲线上出现了三个电流峰,对应的电极电位分别为250mV、50mV、-200mV（vs. Zn2+/Zn）。结合EDS成分分析,可断定这三个电流峰分别对应着Co的电沉积、Co电极上Zn的欠电位沉积和Co-Zn合金的电沉积。恒电位沉积表明,当控制阴极电位在100 mV（vs. Zn2+/Zn）左右时,可得到高纯度的钴镀层;若进行恒电流沉积,则当电流密度为85mA/cm2左右时能够得到高纯度的钴镀层。对Co、Zn的共沉积机理研究表明,Co的电沉积过程和Zn 在Co上的欠电位沉积过程均受扩散过程控制。     

Cl^—对Zn—Ni合人沉积Zn转移电流密度的影响

在氯化物电解液中Zn-Ni合金共沉积存在着由正常共沉积转变成异常共沉积的Zn转移电流密度，该转移电流密度随着Cl^-浓度的增加而增加，而与溶液pH值基本无关，这是由于Cl^-的存在降低了Ni的析出过电位，并对Ni的析出有催化作用之故。     

二甲基亚砜中电沉积钬钴合金的研究

研究了在二甲基亚砜中钬与钴的电解共沉积。测定循环伏安曲线获知钬钴共沉积的沉积电位较钴单独析出为负而较钬的析出为正,属于诱导共沉积类型,恒电位电解表明在一定浓度范围内电位是影响合金成分的主要因素,而镀液组成的影响较小,在－1.8V下恒电位电解得到了均匀、致密的非晶态合金沉积层。     

Cl-对Zn-Fe族元素二元合金共沉积的催化作用

在氯化物电解液中以定电量（10C.cm^-2),恒温40℃电沉积Zn-Fe族元素二元合成,沉积产物用原子吸收光谱分析,根据分析结果,作出相应的电流效率、百分含量及部分极化曲线,镀层形貌采用扫描电镜（SEM）观察,发现：Zn-Fe族元素合金的共沉积为异常共沉积,Cl^-对铁族元素有催化作用,随着Cl^-浓度的增加,降低了铁族元素的过电位,促进铁族元素金属的沉积。     

锌铈混合金属氧化物薄膜电化学沉积的研究

采用自制四电极体系,原位测量锌铈混合氧化物薄膜电沉积过程电极/溶液界面pH的动态变化。电极/溶液界面的pH-时间曲线表明,pH快速上升后达到平衡,且电沉积过电位越大,达到平衡pH值的时间越短,平衡pH值也越高。X射线粉末衍射(XRD)实验证明薄膜沉积物是由ZnO和CeO2组成。电感耦合等离子体(ICP)技术分析了不同电沉积电位、不同电沉积时间下电沉积产物中Ce(Ⅲ)/Zn(Ⅱ)的物质的量比,结果表明Ce(Ⅲ)/Zn(Ⅱ)的物质的量比随着pH值的升高而增加。依据Zn2+离子和Ce3+离子液相和固相中存在形态的热力学数据,计算了2种金属离子的条件溶解度随pH的变化曲线。结合实验测试数据和理论计算结果,讨论了电极表面金属氧化物的电化学沉积机理,并阐明了阴极表面混合金属氧化物的组成取决于液-固两相中金属离子存在形态的热力学性质。     

催化极谱法测定锌电解液中微量钴

在湿法炼锌厂 ,锌电解液中杂质钴对析出锌的质量和锌电解的电流效率影响较大。传统工艺用黄药净化除钴 ,对钴的测定要求是 1μg· ml-1,通常采用亚硝基 - R盐比色法测定。自采用锑盐深度净化工艺后 ,对钴的测定要求为 0 .1 μg· ml-1,亚硝基 - R盐比色法的灵敏度达不到这个要求。本文在文献 [1 ,2 ]基础上采用催化极谱法测定钴 ,在柠檬酸铵 -盐酸羟胺底液中 ,Co( )与丁二酮肟形成的络合物在示波极谱仪上产生波形良好的催化极谱波 ,波峰电位为 - 1 .1 V(vs.SCE)。Zn2 +在此底液中的还原极谱波的波峰电位为 - 1 .3V,严重影响 Co2 +的催化…     

络合吸附溶出伏安法测定茶叶中的痕量锌

通过实验优化支持电解质、pH值、络合剂浓度等实验参数。在溶液中直接以SCN-作配位剂 ,采用玻碳电极同位镀汞的吸附伏安法测定锌。在该体系中 ,Zn2 + 和SCN-配合物可产生灵敏吸附波 ,峰电位为 - 1.372V ,线性范围为 1.96 2～ 130 .8μg/L ,搅拌富集 5min ,检出限可达 8× 10 -10 mol/L。该法用于测定茶叶中的锌 ,平均回收率为 95 .0 %～ 10 2 .5 %。     

电沉积Ni-PSZ梯度镀层过程中阴极电流效率的研究

采用动电位扫描,电化学交流阻抗及扫描电子显微镜研究电沉积Ｎｉ－ＰＳＺ梯度镀层过程中阴极电流效率的变化规律及其机理．结果表明,Ｎｉ－ＰＳＺ复合镀层对氢的析出反应具有催化作用,在镀液中加入ＰＳＺ微粒后,能增大镍还原过电位,降低氢析出过电位,从而不断降低电沉积梯度镀层过程中的阴极电流效率．在电沉积Ｎｉ的过程中,有中间吸附相Ｎｉ＋ａｄｓ生成,ＰＳＺ微粒的加入能优先催化Ｈａｄｓ,加速氢气析出     

Coating on Zinc Surface to Improve the Electrochemical Behavior of Zinc Anodes for Zinc‐Air Fuel Cells

The corrosion of Zn anode, associated with corrosion current and hydrogen evolution reaction, is a major reason for capacity loss and safety problems. As a way of improving the current issue, a newly coating method using difference of melting points has been attempted to synthesize anode materials and found to be highly effective. Effects of corrosion inhibitors are also investigated by diverse electrochemical techniques. The Tafel extrapolation shows the reduced corrosion current compared with that of pure Zn. ZnNi‐2 (Zn:Ni, 95 : 5 wt.%) demonstrates the hydrogen overpotential is shifted to the most negative value as ?1.7 V vs. Hg/HgO.     

Phosphorus‐Doped Graphitic Carbon Nitrides Grown In Situ on Carbon‐Fiber Paper: Flexible and Reversible Oxygen Electrodes

Flexible non‐metal oxygen electrodes fabricated from phosphorus‐doped graphitic carbon nitride nano‐flowers directly grown on carbon‐fiber paper exhibit high activity and stability in reversibly catalyzing oxygen reduction and evolution reactions, which is a result of N, P dual action, enhanced mass/charge transfer, and high active surface area. The performance is comparable to that of the state‐of‐the‐art transition‐metal, noble‐metal, and non‐metal catalysts. Remarkably, the flexible nature of these oxygen electrodes allows their use in folded and rolled‐up forms, and directly as cathodes in Zn–air batteries, featuring low charge/discharge overpotential and long lifetime.     

Electrochemical deposition of Zn on TiN microelectrode arrays for microanodes

Zn was electrochemically deposited onto square TiN electrodes with edge dimensions of 490 μm and 40 μm. These were fabricated by standard microfabrication techniques, which provide an extremely reproducible electrode for experimentation. Reliable constant-potential electrodeposition of Zn on the TiN was performed at −1.2 V, just below the Zn/Zn²⁺ redox potential. At more negative potentials, the hydrogen evolution reaction on TiN interfered with bulk metal electrodeposition, resulting in poor quality Zn films. A two-step plating procedure was shown to be most efficient for electrochemical deposition of Zn, with Zn nucleation on the TiN substrate at high cathodic overpotential during the first step and a second step of bulk metal growth on the nucleated layer at low cathodic overpotential. These results were most consistent with 3D progressive nucleation of Zn on the TiN surface. Using this procedure, deposits of Zn on 490 μm TiN electrodes were uniform. In contrast, Zn deposits on 40 μm electrodes formed high-surface area and volume surface structures resulting from preferential growth at the electrode corners due to enhanced hemispherical diffusion at these sites. This should enable the formation of high surface area, high current density Zn anodes on biocompatible TiN microelectrodes, which could find application as improved microanodes for implantable miniature power supplies, e.g., implantable glucose sensors and internal cardioverter defibrillators.     

Sauerstoffüberspannung in gegenwart verschiedener ionen in abhängigkeit von der aktivität des wassers

The changes of the overpotential of oxygen evolution caused by the change of concentration or activity of water and by the presence of alkali metal ions were investigated in aqueous HClO₄, H₂SO₄ and H₃PO₄ solutions at Pt electrodes.The water content of the solutions was changed by dissolved ?-caprolactam. It was established that the overpotential of electrochemical oxygen evolution at constant current density increases with decreasing water activity and the relation between overpotential and activity of water is rather different in the three acids investigated. The current—voltage curves correspond to the Tafel equation partially with two sections of differing slope.The effect of concentration of alkali metal ions on the overpotential was studied as a function of the water activity. The sequence of the overvoltage increasing effect of the different metal ions is dependent on the activity of the water and on the concentration of the ions.The results indicate that the change of the liquid structure of the water caused by the presence of the different ions and ?-caprolactam can exert an influence on the velocity of oxygen evolution.     

Preparation of Quaternary FeCoMoCu Metal Oxides for Oxygen Evolution Reaction

Molybdenum doping is an effective way to improve the oxygen evolution reaction(OER) properties of catalysts, which can efficiently improve the electronic conductivity, mass transport process, and intrinsic activity of transition metal oxides or hydroxides, especially for those multi-component oxides with more abundant active sites. Herein, we have prepared a quaternary FeCoMoCu metal oxide on Cu foam(FeCoMoCuO_x@Cu) as an efficient OER catalyst. As expected, FeCoMoCuO_x@Cu could exhibit a low overpotential(252 mV at the current density of 10 mA/cm²) and exceptional stability(10000 cycles of CV scans or constant electrolysis for 48 h).     

Application of metal chalcogenide-based anodic electrocatalyst toward substituting oxygen evolution reaction in water splitting

Electrochemical water splitting for producing hydrogen has received increasing attention. However, the large overpotential of oxygen evolution reaction (OER) is a bottleneck in water splitting. Exploiting value-added alternative reactions to replace the OER semi-reaction in water splitting can not only produce valuable products at both electrodes, but also reduce the overpotential of water splitting. Recently, metal chalcogenides (sulfides and selenides) have been widely studied in electrocatalytic reactions. This review concentrates on the recent application of metal chalcogenides in value-added anodic reactions by replacing the OER during electrochemical water splitting, including urea oxidation reaction (UOR), 5-hydroxymethylfurfural electrochemical oxidation reaction (HMF-EOR), which provides the guidance for the rational design of advanced metal chalcogenide electrocatalysts in renewable energy.     

New metal-anion radical framework materials: Co(II) compounds showing ferromagnetic to antiferromagnetic phase transition at about 344 K, and Zn(II) compounds exhibiting terminal anion ligand induced direct white-light-emission

The preparation, X-ray crystallography, EPR, magnetic and luminescent investigation of new metal-anion radical framework materials based on a new anion radical ligand generated by in situ deprotonation of a stable zwitterionic radical are described herein. N,O,N-tripodal anion radical ligand (bipo(-)˙) links metal cations, giving rise to four isostructural one-dimensional metal-organic frameworks, [M(bipo(-)˙)(L)](n) [M = Zn, L = HCOO(-) (1), SCN(-) (1a), N(3)(-) (1b); M = Co, L = Br(-) (3)]. The tripodal bipo(-)˙ ligand and one co-ligand, 1,4-benzenedicarboxylate, coordinate to metals leading to two isostructural two-dimensional metal-organic frameworks, [M(bipo(-)˙)(BDC)(0.5)](n) [M = Zn (2) and Co (4)]. The two Co(II) compounds are the first examples that exhibit unusual ferromagnetic to antiferromagnetic phase transition with transition temperature over room temperature, which can be demonstrated by the cooling and warming measurements of susceptibility. Compound 4 also exhibits long-range magnetic ordering with the critical temperature at about 44 K proved by ac susceptibility measurements. The metal-radical frameworks exhibit distinctly different fluorescence emissions. Especially, the isomorphous one-dimensional Zn(II) compounds show interesting terminal anion ligand-induced photoluminescent color changes, including direct and invariable white-light-emission with terminal SCN(-) ligand.