Anodic electrodeposition of copper oxide/hydroxide films by alkaline solutions containing cuprous cyanide ions

A novel procedure of anodic electrodeposition of copper oxides and hydroxides on glassy carbon and noble metals electrodes in an alkaline medium is described. The deposited films have been investigated by electrochemical and by X-ray photoelectron spectroscopy (XPS) techniques. The copper films are deposited on the electrode surface as Cu(OH)₂ and CuO after the dissociation of the Cu(CN)_n^1?n complex caused probably by the formation of Cu^III species at relatively high applied potentials (i.e. 0.5 V). The resulting active copper films, independently of the electrochemical procedure adopted (i.e. potentiostatic or potentiodynamic conditions), appear to be uniform, smooth and with a good degree of adhesion on the electrode surface The electrocatalytic properties of the copper deposited films were investigated in an alkaline medium for the electrooxidation of several classes of organic compounds.     

Mass transfer and mechanism of electrochemical reduction of copper(II) from aminoacetate electrolytes

The paper presents calculated and experimental data on the determination of the ionic composition of an aminoacetate (glycine) electrolyte for copper plating in the bulk electrolyte and in the cathode layer over a wide pH range. The discharge mechanism of complexes of copper(II) with aminoacetate has been studied using voltammetry and chronopotentiometry. It has been shown that in an acid medium, hydrated copper ions and the CuGl⁺ complex and in a neutral medium the CuGl₂ complex are discharged (Gl^?=glycine). In an alkaline medium, the discharge of ions is a complicated process and depends on the potential and concentration of the alkali. At low polarization values, an oxide film is formed on the cathode surface, and at high polarization values all copper complexes are discharged directly to metal.     

Initial stages of the electrocrystallization of copper from non-cyanide alkaline bath containing glycine

An electrochemical study on the initial stages of copper electrodeposition onto nickel substrate from non-cyanide alkaline bath containing glycine as complexing agent is presented in this work. The studied parameters were copper concentration, glycine concentration, and deposition potential. Upon scanning in the negative direction, one cathodic peak was observed, which is associated to copper electrodeposition from CuL₂ complex at pH 10.0 (where L⁻ is the anion form of glycine). Analysis of the chronoamperograms indicates time-dependent nucleation mechanisms. A progressive nucleation mechanism without overlap of diffusion zones, which involved an electron transfer reaction (at short times) and a progressive nucleation mechanism with overlap of diffusion zones (at long times). Non-linear fitting methods were applied to obtain the growth and nucleation kinetic parameters from theoretical equations proposed to describe this system.     

Liquid membrane system for extraction and electrodeposition of silver(I)

The process of Ag⁺ ions extraction from nitric solutions by bulk liquid membranes containing di(2-ethylhexyl)phosphoric acid and tri-n-octylamine accompanied with silver(I) electrodeposition from perchloric acid solutions is studied at galvanostatic electrodialysis. The effects of the current density as well as of composition of the liquid membrane and aqueous solutions on the rate of the silver(I) transport are determined. More than 90% of silver ions was extracted from the feed solution containing 0.01 mol l⁻¹ AgNO₃ and about 40% of metal was electrodeposited during 1 h of electrodialysis. Sound adherent silver coatings have been deposited on platinum and copper cathodes.     

Electrochemical analysis of ascorbic acid using copper nanoparticles/polyaniline modified glassy carbon electrode

The electrosynthesis of polyaniline (PANI) film has been achieved on glassy carbon electrode (GCE) in a novel ionic liquid medium by means of cyclic voltammetry (CV). Then a copper nanoparticles (Cu-NPs) film was in situ electrochemically deposited on the surface of PANI/GCE. Electrochemical behavior and surface characteristics of the Cu-NPs/PANI/GCE were studied using cyclic voltammetry, scanning electron microscopy (SEM) and the results confirmed the presence of PANI and Cu-NPs on the electrode surface. Cu-NPs were highly dispersed and firmly stabilized by surface attachment of the PANI, which was prepared in ionic liquid and strongly attached to the electrode surface. The Cu-NPs/PANI/GCE showed excellent electrocatalytic activity toward the oxidation of ascorbic acid (AA) under weakly basic conditions. Amperometry was carried out to determine the concentration of AA at 0.2 V, and a good linear concentration range from 0.005 to 3.5 mM was found. The Cu-NPs/PANI composite film on GCE surface showed good reproducibility and stability.     

张应力对面颌肌细胞烟碱样乙酰胆碱受体基因表达影响的体外研究

目的评价张应力作用后面颌肌细胞烟碱样乙酰胆碱受体基因表达变化。方法采用已经建立的面颌部肌细胞体外力学刺激—细胞培养模型,半定量RT-PCR技术检测nAChRα1亚基基因加力前后转录水平变化。结果未发现有明显统计学差异。结论单纯张应力对体外培养小鼠颌面部骨骼肌细胞nAChR基因表达影响较小。     

Probing interfacial dynamics by phase-shift interferometry in thin cell electrodeposition

In this article the relevance of phase-shift interferometry as an in situ probe for interfacial dynamics in thin cells is emphasized. The efficiency of this technique for dynamical studies of diffusion layers is illustrated by selected examples of electrodeposition and corrosion experiments in thin cells. After a brief survey of the application of interferometry to electrochemistry we turn to phase shift interferometry (PSI) and we show successively that this real time technique can be used for probing both transport processes and chemical mechanisms close to an active surface (μm scales).     

Electrochemical quartz crystal microbalance study of copper adatoms on Au(111) electrodes in solutions of perchloric and sulfuric acid

The adsorption of anions on highly ordered (111)-type gold electrodes with and without Cu adatoms in perchloric and sulfuric acid electrolyte solutions was investigated on an electrochemical quartz crystal microbalance. A distinct increase in mass due to the specific adsorption of hydrated bisulfate and perchlorate anions was observed in Cu²⁺-free solutions and their amounts were determined as a function of the potential. The composition of the Cu-adlayer (θ_Cu and θ_anion, coverages of Cu adatoms and co-adsorbed anions) during formation or removal in the potential sweep was also determined in both electrolyte solutions. A pair of reversible anodic and cathodic peaks in the voltammogram for the first Cu-upd region in H₂SO₄ was found to correspond well to the reversible changes in θ_Cu and θ_anion. In contrast, asymmetric features of the voltammograms for the second Cu-upd region in H₂SO₄ and for whole processes in HClO₄ corresponded to the large hysteresis in changes of θ_Cu and θ_anion, probably originating from a slow rearrangement of both species.     

Effect of Cd2+ on the electrodeposition of nickel from sulfate solutions. Part II: Polarisation behaviour

The effect of Cd²⁺ on the electrodeposition of nickel from a sulphate bath in the absence and presence of boric acid has been investigated. The presence of Cd²⁺ ion suppresses the nickel electrodeposition and shifts the deposition potential to more negative values. The cathodic polarisation is found to depend on the composition of the electrolytic bath. For the various baths investigated, the cathodic polarization order is found to decrease in the order NiSO₄ + H₃BO₃ > NiSO₄ + H₃BO₃ + Na₂SO₄ > NiSO₄ + Na₂SO₄ > NiSO₄. For the Ni²⁺ electroreduction reaction on stainless steel and nickel substrates the exchange current density decreases with increase in Cd²⁺ concentration in the electrolytic bath. However the Tafel slope and transfer coefficient are unaffected.     

Studies of the electrodeposition of platinum metal from a hexachloroplatinic acid bath

The mechanism of platinum deposition onto carbon from a bath containing H₂PtCl₆ in 0.1 M HCl is discussed. Although voltammograms show multiple cathodic waves, it is shown that they all result from the reduction of Pt(IV) to Pt(0) and there is no evidence for Pt(II) as a stable intermediate at any potential; the multiple waves arise because the hexachloroplatinic acid exists in solution as a mixture of kinetically inert Cl⁻/H₂O complexes. The nucleation of the Pt centres on carbon is a very slow process even with a large overpotential and this leads to surfaces with well dispersed hemispherical nuclei. Moreover, each Pt centre appears to grow only to a limiting size before growth ceases.     

Mechanistic studies of electrodeposition for bioceramic coatings of calcium phosphates by an in situ pH-microsensor technique

A pH-microsensor technique was developed to measure in-situ the pH value at the titanium alloy ∣ solution interface for the first time during the electrodeposition process of calcium phosphate coatings. Electrochemically prepared iridium oxide was used as a pH sensitive material, which is of a good response behavior in the measured solutions. The pH response slope was ?70.2 mV/pH at 60°C. The results indicated that the interfacial pH increased with the applied current density, first jumped to a maximum, then slowly decreased at the controlled current density during the electrodeposition process. Incorporating the results of composition and structure of electrodeposition coatings characterized by X-ray diffraction (XRD) patterns and Raman spectra, the measurement of the interfacial pH was informative for further understanding of the electrodeposition mechanism of calcium phosphates. The interfacial pH may determine the precipitation reaction and the electrodeposition products at the titanium surface.     

Surface copper immobilization by chelation of alizarin complexone and electrodeposition on graphite electrodes,and related hydrogen sulfide electrochemistry; matrix isolation of atomic copper and molecular copper sulfides on a graphite electrode

The irreversibly adsorbed alizarin complexone (AC) was employed to immobilize and maintain Cu^II ions on the graphite electrode. The coordination chemistry between the adsorbed alizarin complexone ligand and the Cu^II ion on the surface was examined by surface cyclic voltammetry. Upon reduction of the Cu^II center to a Cu⁰ atom, a submonolayer of individual atoms of Cu⁰ rather than a continuous layer is formed on the electrode surface. The immobilized surface displays electrocatalytic activity towards the oxidation of sulfide ion from [S^2?] ion to S⁰. The electrocatalytic activity for the sulfide oxidation on a [Cu^II(AC)]^? adsorbed electrode is shown to be essentially identical with that of a electrode that contains an electrodeposited submonolayer of Cu⁰. The active catalyst in both cases is identified to be a submonolayer of cupric sulfide. The electrochemistry of the Cu⁰ submonolayer-coated electrode in aqueous solution containing hydrogen sulfide was also examined. When the modified electrode was polarized from ?1.1 V to 0.2 V, three electrode processes were observed. The first, near ?0.7 V, is a surface reaction between surface Cu⁰ and adsorbed [S^2?] ion to form a submonolayer of cuprous sulfide. The second appeared near ?0.23 V and is another surface process between Cu₂S and adsorbed sulfide ion to form a submonolayer of cupric sulfide. The third reaction is the electrochemical oxidation of sulfide ion catalyzed by CuS to form sulphur which deposits on the electrode surface when the potential is positive of ?0.2 V.     

Electrochemical oxidation of mono- and disaccharides at fresh as well as oxidized copper electrodes in alkaline media

The electrochemical oxidation of mono- and disaccharides in a sodium hydroxide solution at a fresh as well as on an oxidized Cu rotating disk electrode (RDE) is reported. It is demonstrated herein that the oxidation of disaccharides is not similar to that of monosaccharides as exemplified by a comparative electrooxidation study of glucose and maltose as typical mono- and disaccharides, respectively. The oxidation of monosaccharides (glucose, galactose, mannose) at a fresh Cu RDE gave approximately 12 electrons (n), and that of disaccharides (cellobiose, isomaltose, laminaribiose, mannobiose, maltose) gave n ranging between 3 and 13. The electrooxidation of disaccharides was also studied as a function of sodium hydroxide concentration as well as applied potential, but these parameters were not found to affect the number of electrons transferred or the heterogeneous rate constants to a significant degree. Further investigations of the electrooxidation of glucose and maltose at an oxidized Cu RDE showed that, for maltose, the number of electrons transferred and the heterogeneous electrooxidation rate constant (k) were dependent on the oxidative treatment time. This dependence was not associated with an increased surface roughness of the electrode as the n value for glucose was not affected by the oxidative treatment time. Up to n=19 could be observed for maltose and the kinetic constant reached 5×10^?3 cm s^?1 compared to that for a freshly cleaned electrode (5×10^?4 cm s^?1).     

Study of the influence of the polyalcohol sorbitol on the electrodeposition of copper–zinc films from a non-cyanide bath

The electrodeposition of copper–zinc on to AISI 1010 steel from an alkaline non-cyanide solution containing sorbitol was investigated, with various proportions of the metal ions in the bath. Voltammetric curves indicated that the complexation of copper ion by sorbitol is beneficial, since the copper complex reduction potential is close to that of the zincate ion, implying that codeposition of copper and zinc should occur. EDS analysis showed that varying the ratio of copper to zinc ions in the plating bath affects the proportion of metals in the deposits, leading to golden or greyish bright films, even in the high-hydrogen-evolution potential region, indicating that sorbitate anions prevent the deposits becoming darker in this region. The narrow variation in film colour at various deposition potentials and charge densities showed that rigorous control of the alkaline-sorbitol plating bath and deposition conditions is not necessary. SEM analysis showed that the films were without stress and the substrate was fully covered. X-ray spectra suggested that a mixture of Cu₈0 and CuZn₂ alloy was deposited at ?1.14 V in all the baths studied while Cu_0.61Zn_0.39 (Cu-70 bath), Cu₅Zn₈ (Cu-50 bath) and CuZn₅(Cu-30 bath) films were deposited at both ?1.45 and ?1.60 V.     

Effects of sodium sulfamate on electrodeposition of Cu(In,Ga)Se2 thin film

Cu(In,Ga)Se₂ thin films have been prepared by electrodeposition from chloride electrolytes using sodium sulfamate as a complexing agent. Cyclic voltammograms indicate that sodium sulfamate can inhibit the reduction of Cu²⁺, Cu⁺ and H₂SeO₃, and accordingly hinder the formation of copper selenides. EDS analysis reveals that with the increase of sodium sulfamate concentration in the bath, atom ratio (Cu + Se)/(In + Ga) decreases while gallium content increases, and the film composition transforms from Cu-rich to Cu-poor. SEM and Raman spectra also show that copper selenides phases in electrodeposited films diminish with the increase of sodium sulfamate concentration.     

Effect of sodium dodecylsulfate on copper corrosion in sulfuric acid media in the absence and presence of benzotriazole

The effect of sodium dodecylsulfate (SDS) on the copper corrosion in 0.5 mol dm^?3 H₂SO₄ solution has been studied by electrochemical and in situ Raman spectroscopic measurements. It has been shown that SDS is a corrosion inhibitor for copper on the entire range of potentials studied and presents a synergetic effect on the inhibitive action of benzotriazole (BTAH). It has been also observed that SDS inhibits the H⁺/H₂ reaction on the copper electrode below or above the cmc. The surfactant film, at ?750 mV (SCE) obeys a Langmuir adsorption isotherm considering 1.2 surface sites for each adsorbed SDS molecule, when [SDS]<cmc. The equilibrium adsorption constant, K=1.7×10³ mol dm^?3, suggests the presence of a chemical adsorption. The spectroscopic results have shown that the SDS adsorbs on the copper surface with both moieties, the hydrophobic and hydrophilic, interacting with the copper surface. The in situ spectroelectrochemical results have also shown that SDS co-adsorbs on the copper surface in the presence of BTAH and that the structure of the co-adsorbed SDS molecules is different from that observed in the absence of BTAH.     

Oxygen reduction on copper in neutral NaCl solution

The reduction of oxygen on copper in neutral unbuffered 1 mol dm^?3 NaCl has been studied using rotating ring-disc electrodes at six oxygen concentrations equivalent to atmospheres of 2% O₂ + N₂ to 100% O₂. Steady-state potentiostatic measurements show that the reaction is first order with respect to [O₂] and that, following adsorption of O₂, the first electron transfer is rate determining. In 50% O₂ + N₂ and 100% O₂, a cathodic oxygen reduction peak is observed in both potentiodynamic and potentiostatic experiments at a disc potential of ?0.3 to ?0.4 V/SCE. The reaction is dominated by the overall four-electron reduction to OH^?, with only small amounts of peroxide detected by the ring electrode at disc potentials corresponding to the formation of the cathodic oxygen reduction peak. Tafel slopes increase with [O₂] and vary from ?0.13₅ V in 2% O₂ + N₂ to a limiting value of ?0.16 V to ?0.18 V in air, 50% O₂ + N₂ and 100% O₂.The results are explained by a mechanism involving oxygen reduction on two types of surface site with different reactivities. The most catalytic surface is believed to comprise Cu(0) and Cu(I) sites, where the Cu(I) species is stabilized as Cu(OH)_ads and/or submonolayer Cu₂O. The less catalytic site consists of Cu(0) only. Oxygen reduction is believed to proceed by a series pathway involving an adsorbed peroxide intermediate on both sites. Peroxide is reduced to OH^? prior to desorption at Cu(0) sites, but some is released before being reduced at Cu(0)/Cu(I) sites. Surface coverage by catalytic Cu(0)/Cu(I) species is favoured by a higher interfacial pH and more positive disc potentials.     

Electrochemical adsorption studies of urea on copper surface in alkaline medium

The inhibitive action of urea on the corrosion behavior of copper was investigated in borate buffer pH (8.4) by means of cyclic voltammetry and electrochemical impedance spectroscopy (EIS). A consistent trend of increase in inhibition efficiency was observed as a function of concentration of urea. The adsorption of urea on copper surface was found to obey the Langmuir adsorption isotherm with ΔG = −35.2 kJ/mole and adsorption constant K = 2.7 × 10⁴ dm³/mole. Impedance spectroscopic measurements confirmed that charge transfer resistance increases in presence of urea upon increasing its concentration.     

铜离子对牙各矿化成分破骨细胞性吸收的体外调控

目的研究铜离子对破骨细胞体外吸收人牙磨片功能的影响。方法体外分离、培养兔破骨细胞，与玻片和灭活人牙磨片共同培养，加入不同浓度的铜离子。抗酒石酸酸性磷酸酶染色鉴定玻片上的破骨细胞，显微摄影分析破骨细胞吸收造成的牙磨片上的吸收陷窝，原子吸收分光光度法测定溶出的钙，并将实验组上清液中钙离子浓度与对照组相比，定义为矿化组织吸收指数，以评价破骨细胞的功能。结果体外成功分离培养出多核的、抗酒石酸酸性磷酸酶染色（＋）的破骨细胞。破骨细胞吸收牙磨片时，首先在接近牙骨质或牙本质的部位开始形成吸收陷窝；破骨细胞在牙磨片上形成的吸收陷窝与骨片相比，数量较少，体积较小，多为正圆形；吸收深度较浅，常为大面积的浅吸收。（1×10^-14）～（1×10^-4）mol／L铜离子均能抑制矿化组织吸收，实验组矿化组织吸收指数均小于1。培养第3天，1×10^-10mol／L铜离子与对照组相比，其抑制效果差异有统计学意义（P〈0．05）。培养第7天，1×10^-4mol／L、（1×10^-10）～（1×10^-12）mol／L铜离子均能显著抑制矿化组织吸收（P〈0．05），但各浓度之间相比差异无统计学意义（P〉0．05）。结论一定浓度的铜离子可以抑制破骨细胞在牙磨片上的吸收。