Electrodeposition of white gold alloys: an electrochemical,spectroelectrochemical and structural study of the electrodeposition of Au-Sn alloys in the presence of 4-cyanopyridine

A bath for the electrodeposition of Au-Sn alloys is proposed and the properties of the deposit obtained have been studied, in view of applications in the field of white precious metal plating and electroforming. 4-Cyanopyridine has been employed as an organic additive to confer stability to the bath and compactness to the deposit. The electrochemical behaviour of the bath has been investigated by means of cyclic voltammetry, stripping potentiodynamic scans, open circuit potential decay measurements and potentiostatic transients. The nucleation behaviour of the system has been studied on glassy carbon electrodes. The electrodic behaviour of 4-cyanopyridine was investigated as a function of electrode potential by in situ Raman spectroscopy. The composition of the alloys was evaluated by electron dispersive spectroscopy, the crystalline structure by X-ray diffraction and the morphology by scanning electron microscopy. The effects of the additive on the crystalline structure and on the morphology of the electrodeposits have been highlighted. Potential-dependent adsorption, reorientation and cathodic reactivity of 4-cyanopyridine during the alloy electrodeposition process have been assessed.Presented at the 3rd International Symposium on Electrochemical Processing of Tailored Materials held at the 53rd Annual Meeting of the International Society of Electrochemistry, 15–20 September 2002, Düsseldorf, Germany     

Effect of cations of alkali metals and ammonium on the process of deposition and structure of iron-tungsten alloys

It is established that potassium ions facilitate expansion of the current density range where crystalline alloy deposits form. This is presumed to be connected with an increase in the hydrogen overvoltage, in connection with which alloy deposits turn amorphous at higher current densities and potentials corresponding to these, at which hydrogen evolution accelerates. A high alloy deposition rate and a sufficiently negative potential of its deposition are conditions not sufficient for transition from large-crystal to nanocrystalline and amorphous deposits. Here, a more important role is played by hydrogen that inserts itself into the crystal lattice. As one could assume, hydrogen in this case facilitates preservation of the emerging nonequilibrium structures, hindering crystallization processes as a result the iron hydride formation.     

Influence of bath composition and deposition parameters on nanostructure and thermal stability of gold

Nanocrystalline gold is electrodeposited from a stable nontoxic bath, in which Au⁺ is stabilized by complex formation with 3-mercapto-1-propanesulfonic acid sodium salt. Nanoscaling is achieved by pulse techniques. The crystallite size is strongly dependent on physical and chemical process parameters, such as pulse duration, current density, bath temperature, type, and amount of additives; especially, we observe a decrease of the crystallite size down to 16 nm by the proper choice of current density and temperature, and down to 7 nm by the use of additives. The thermal stability of nanocrystalline gold is investigated by in situ high-temperature X-ray diffraction; nanogold exhibits a thermal stability up to 673 K. An activation energy of 37 kJ mol⁻¹ is determined for the grain-growth kinetics.Paper presented at the “Jahrestagung der Fachgruppe Angewandte Electrochemie der Gesellschaft Deutscher Chemiker, Düsseldorf, 11.–14.06.2005”     

Electrochemical and structural characterization of sulfonated polysulfone

We describe the synthesis, as well as the electrochemical and structural characterization, of sulfonated polysulfone intended for use in PEM fuel cells. Starting from a commercial polysulfone, we assessed the performance of these prepared ionomers using synthesis protocols compatible with industrial production. The efficiency of the trimethylsilyl chlorosulfonate and chlorosulfonic acid reagents in the sulfonation process was confirmed by ¹H NMR, FTIR, elemental analysis, chemical titration and thermal analysis (DSC and TGA). Chlorosulfonic acid was the most effective sulfonation reagent. However, based on SEC-MALLS, this reagent induced degradation of the backbone that is detrimental to the thermomechanical stability and lifespan of the membranes. The electrical characterization of the membranes was undertaken using impedance spectroscopy in contact with different HCl aqueous solutions at various temperatures. The activation energies, which ranged from 8.2 to 11 kJ/mol, were in agreement with the prevailing proton vehicular mechanism.     

Electrochemical deposition and characterization of SnS thin films

Thin films of SnS were cathodically deposited onto stainless steel substrates from bath containing 0.025 M SnSO₄, 0.25 M KSCN and 0.25 M Na₂SO₄. The mechanism of electrochemical co-deposition of tin and sulphur was investigated by cyclic voltammetry. Analysis of the chronoamperometric current–time transients suggested that, in the potential range −560 to −590 mV vs saturated calomel electrode, the electrodeposition of SnS involved progressive nucleation model. However, at a potential −600 mV, the electrodeposition involved instantaneous nucleation model. The deposits have been characterized by scanning electron microscopy, X-ray diffraction and optical measurements. SnS films were found to be polycrystalline with an optical energy gap of 1.38 eV.     

Electrochemical and structural characterization of lithium titanate electrodes

Lithium titanate (LTO) materials of different particle size, surface area, and morphology were characterized by constant current cycling and cyclic voltammetry. By examining the particles and electrodes with scanning electron microscopy, we show that particle morphology, in addition to particle size, has important implications for high-rate performance. Large agglomerates, even when porous and made of small crystallites, cannot effectively form homogenous electrodes with the polymer binder and carbon conducting diluents; hence, low power performance results. Another nanostructured LTO of very high surface area was found to have poor electrochemical performance most likely due to its high concentration of structural defects. We recommend further development in nanoparticles of LTO of optimal crystallinity as well as improved electrode homogeneity through the use of more compatible binders and conducting diluents and better electrode processing techniques. Simultaneous realization of these imperatives should facilitate the development of LTO-based high-power batteries for automotive applications.     

Pt-Ni与Pd-Ni纳米薄膜的电化学制备和乙醇电催化性能研究(英文)

通过电沉积法在Ti基体上制备具有纳米结构的Pt-Ni和Pd-Ni薄膜,前者呈纳米花瓣形状,厚度为10～20 nm,后者主要由纳米颗粒组成,大小为50～60 nm.XRD测试结果显示,Pt-Ni和Pd-Ni纳米薄膜结晶程度较差.循环伏安法测试薄膜对乙醇电催化氧化的性能,结果表明Pt-Ni和Pd-Ni纳米薄膜可使乙醇起始氧化电位分别负移至-0.74 V和-0.71 V,且在碱性介质中加Ni可提高催化剂的活性和抗毒化性能.     

Electrochemical deposition and characterization of copper-cobalt oxide layers by electrodeposition

The copper-cobalt oxide (Cu₂CoO₃) was successfully elaborated on indium tin oxide (ITO) substrate using the co-electrodeposition method in citric acid (C₆H₈O₇) solution at a temperature of 70 °C. The co-electrodeposition process of Cu₂CoO₃ thin films was realized by the electrochemical technique: cycle voltammetry. In this work, the effect of the cycle number on the cyclic voltammetry (CV), structural, and morphological of the Cu₂CoO₃ thin films were discussed. The (CV) showed that the current density of the co-electrodeposition of Cu₂CoO₃ decreases with the number of cycles. The X-ray diffraction (XRD) analysis revealed that the co-electrodeposition copper-cobalt oxide (Cu₂CoO₃) nanocrystallites with orthorhombic crystal structures. The analysis of the morphological surface by scanning electron microscopy (SEM) of copper-cobalt oxide indicated the formation of two types of crystals of different shapes: pyramidal and spherical corresponding to CoO₂ and Cu₂O respectively.     

Electrochemical Synthesis of Plasmonic Nanostructures

Thanks to their tunable and strong interaction with light, plasmonic nanostructures have been investigated for a wide range of applications. In most cases, controlling the electric field enhancement at the metal surface is crucial. This can be achieved by controlling the metal nanostructure size, shape, and location in three dimensions, which is synthetically challenging. Electrochemical methods can provide a reliable, simple, and cost-effective approach to nanostructure metals with a high degree of geometrical freedom. Herein, we review the use of electrochemistry to synthesize metal nanostructures in the context of plasmonics. Both template-free and templated electrochemical syntheses are presented, along with their strengths and limitations. While template-free techniques can be used for the mass production of low-cost but efficient plasmonic substrates, templated approaches offer an unprecedented synthetic control. Thus, a special emphasis is given to templated electrochemical lithographies, which can be used to synthesize complex metal architectures with defined dimensions and compositions in one, two and three dimensions. These techniques provide a spatial resolution down to the sub-10 nanometer range and are particularly successful at synthesizing well-defined metal nanoscale gaps that provide very large electric field enhancements, which are relevant for both fundamental and applied research in plasmonics.     

硫脲对镍电沉积的作用

应用循环伏安和阻抗＿电位法研究了硫脲(TU)对玻碳电极和镀镍玻碳电极上镍沉积过程的影响.结果表明,在玻碳电极上镍的电沉积呈现明显的电化学成核机理,而在镀镍玻碳电极上则无此特征.TU的存在虽阻碍了Ni晶核的形成,但却能加速晶粒的生长.     

Synthesis and characterization of Cu(II) and Ni(II) complexes of some 4-bromo- N -(di(alkyl/aryl)carbamothioyl) benzamide derivatives

4-Bromo-N-(di-R-carbamothioyl)benzamide (R = methyl, ethyl, n-propyl, n-butyl and phenyl) ligands and their Ni(II) and Cu(II) complexes have been synthesized and characterized by elemental analyses, FT-IR and ¹H-NMR spectroscopy. The crystal and molecular structure of bis(4-bromo-N-(di-n-propylcarbamothioyl)benzamido)nickel(II) has been determined from single crystal X-ray diffraction data. It crystallizes in the triclinic, space group P 1, Z = 2 with a = 9.286(2) Å, b = 13.215(3) Å, c = 14.125(3) Å, α = 64.180(5)°, β = 85.483(6)°, γ = 83.067(5)°, V = 1548.3(7) ų and D _Calcd = 1.594 mg m^?3. Loss of the N–H proton resonance and the N–H stretching vibration and the shift of the ν _C=O and ν _C=S stretching vibrations confirm formation of the metal complexes. These studies have shown that the metal complexes are neutral cis-[ML₂].     

Development of a Novel Electrochemical Sensor Based on Gold Nanoparticle-Modified Carbon-Paste Electrode for the Detection of Congo Red Dye

In this study, gold nanoparticles (AuNPs) were electrodeposited on samples of a carbon-paste electrode (CPE) with different thicknesses. The prepared AuNPs were characterized using different analysis techniques, such as FTIR, UV–Vis, SEM, EDX, TEM images, and XRD analysis. The fabricated modified electrode AuNPs/CPE was used for the sensitive detection of Congo red (CR) dye. Electrochemical sensing was conducted using square-wave voltammetry (SWV) in a 0.1 M acetate buffer solution at pH 6.5. The proposed sensor exhibited high efficiency for the electrochemical determination of CR dye with high selectivity and sensitivity and a low detection limit of 0.07 μM in the concentration range of 1–30 μM and 0.7 μM in the concentration range of 50–200 μM. The practical application of the AuNPs/CPE was verified by detecting CR dye in various real samples involving jelly, candy, wastewater, and tap water. The calculated recoveries (88–106%) were within the acceptable range.     

Synthesis and characterization of nickel and copper complexes with 2,2-diphenyl- N -(alkyl(aryl)carbamothioyl)acetamide: The crystal structures of HL1 and cis -[Ni(L1)2]

2,2-diphenyl-N-(R-carbamothioyl)acetamide (R = diethyl, dipropyl, dibutyl, dihexyl, diphenyl and morpholine-4) and their Ni²⁺ and Cu²⁺ complexes have been synthesized and characterized by elemental analyses, IR spectroscopy and ¹H-NMR spectroscopy. The spectroscopic data are consistent with the ligand and the metal complexes containing two O, S chelated ligands. 2,2-diphenyl-N-(diethylcarbamothioyl)acetamide, HL¹, and bis(2,2-diphenyl-N-(diethylcarbamothioyl)acetamido)nickel(II), Ni(L¹)₂, were characterized by a single crystal X-ray diffraction study. HL¹ complex, C₁₉H₂₂N₂OS, crystallizes monoclinic, space group P2₁/c, with Z = 4, and unit cell parameters a = 14.964(2), b = 13.026(2), c = 9.0123(15) Å, β = 96.314(4)°. Ni(L¹)₂ complex, C₃₈H₄₂N₄O₂S₂Ni, crystallizes in monoclinic space group P2₁/c, with Z = 4, and unit cell parameters a = 15.434(6), b = 13.464(5), c = 17.679(7) Å, β = 108.477(11)°. The ligands coordinate bidentate to metal yielding neutral complexes of the type cis-[ML₂].     

Synthesis and characterization of N -(alky(aryl)carbamothioyl)cyclohexanecarboxamide derivatives and their Ni(II) and Cu(II) complexes

N-(R-carbamothioyl)cyclohexanecarboxamides (R: diethyl, di-n-propyl, di-n-butyl, diphenyl and morpholine-4) and their Ni(II) and Cu(II) complexes have been synthesized and characterized by elemental analyses, FT-IR and NMR methods. N-(diethylcarbamothioyl)cyclohexanecarboxamide, HL¹, C₁₂H₂₂N₂OS, crystallizes in the orthorhombic space group P2₁2₁2₁, with Z = 4, and unit cell parameters, a = 6.6925(13) Å, b = 9.0457(18) Å, c = 22.728(5) Å. The conformation of the HL¹ molecule with respect to the thiocarbonyl and carbonyl moieties is twisted, as reflected by the torsion angles O1–C6–N2–C5, C6–N2–C5–N1 and S1–C5–N2–C6 of 1.68°, ?67.47° and 115.50°, respectively. The structure of HL¹ also shows a delocalization of the π electrons of the thiocarbonyl group over the C–N bonds. The ring puckering analysis shows that the cyclohexane ring has a chair conformation. The bis(N-(morpholine-4-carbonothioyl)cyclohexane carboxamido)nickel(II) complex, Ni(L⁵)₂, C₂₄H₃₈N₄NiO₄S₂, crystallizes in the monoclinic space group P2₁/c, with Z = 4, and unit cell parameters, a = 16.919(3) Å, b = 8.3659(17) Å, c = 19.654(4) Å, β = 107.43(3)°. Ni(L⁵)₂ is a cis-complex with a slightly distorted square-planar coordination of the central nickel by two oxygen and two sulfur atoms.     

Double template electrochemical deposition and characterization of NiCo and NiCu alloys nanoparticles and nanofilms

The principle of double template deposition technique was developed to prepare NiCo and NiCu alloy nanomaterials. Ordered particles of about 800 nm high were obtained by reduction of ions from aqueous solution into the pores of anodic aluminum oxide (AAO) membrane with intact barrier layer. The size of the nanoparticles was significantly reduced by combination of AAO and the hexagonal phase of a lyotropic liquid crystal. The scanning tunneling microscopy (STM) micrograph of the material prepared in the presence of liquid crystal reveals the hexagonal array of cylindrical pores. The corrosion potential of the alloy nanofilm shifted to more negative values when the sizes of the particles decrease. The anodic linear sweep voltammetry shows, in each case, various current peaks characteristic of the dissolution of chemical elements in the film.     

Electrochemical synthesis of silver nanoparticles-coated gold nanoporous film electrode and its application to amperometric detection for trace Cr(VI)

A simple and rapid approach for the electrochemical synthesis of Ag nanoparticles-coated gold nanoporous film (AgGNF) on a gold substrate was reported. The solid gold electrode (SGE) was directly anodized under a high potential of 5 V, and then reduced to obtain gold nanoporous film (AuNF) by freshly prepared ascorbic acid. The Ag nanoparticles (AgNPs) were grown on the AuNF electrode by potential-step electrodeposition. The resulting AgGNF composites electrodes were characterized by scanning electron micro...     

Synthesis and structural characterization of ferrocenyl indenyl derivatives

In this study, four ferrocenyl indenyl derivatives, C₉H₇–C≡C–Fc (1), C₉H₇–C≡C–Ph–Fc (2), C₉H₇–C≡C–Ph–C≡C–Fc (3), and C₉H₇–Ph–C≡C–Fc (4) (where C₉H₇=indenyl; Fc=C₅H₅FeC₅H₄; Ph=C₆H₅), have been synthesized by Sonogashira and Suzuki cross-coupling reactions and characterized by elemental analysis, and FT-IR, ¹H, ¹³C-NMR, and MS spectroscopic methods, respectively. The molecular structures of 1, 2, and 4 were determined by X-ray single crystal diffraction. Two molecules appeared in the crystal structure of 4, and they interact through an intermolecular hydrogen bond. The electrochemical redox potential differences in 1–4 were investigated using cyclic voltammetry and calculations.     

纳米结构ZnO在TiO_2薄膜上的电化学沉积及其表征

在三电极体系中,以硝酸锌水溶液作为电解液,采用阴极还原电沉积法成功实现了一维纳米结构ZnO阵列在TiO2纳米粒子/ITO导电玻璃薄膜基底上的沉积,并通过XRD、SEM、EDS和PL光谱等方法对样品进行了表征.重点研究了薄膜基底、电解液浓度、沉积时间、六次亚甲基四胺(HMT)的引入对ZnO沉积及其发光性质的影响.结果显示:与ITO玻璃基底相比,ZnO更易于在TiO2纳米粒子薄膜上实现电化学沉积.ZnO属于六方晶系的铅锌矿结构,并且沿着c-轴方向表现出明显的择优化生长,以形成垂直于基底的ZnO纳米棒阵列.延长沉积时间、增加电解液浓度和引入一定量的HMT等均对ZnO的生长有促进作用,进而使其纳米棒的结晶度和取向程度提高,进而解释了所得的薄膜分别约在375和520nm处表现出ZnO的强而窄的带边紫外光发射峰和弱而宽的表面态绿光发射带.     

Electrochemical deposition and characterization of mixed-valent rhenium oxide films prepared from a perrhenate solution

Cathodic electrodeposition of mixed-valent rhenium oxides at indium tin oxide, gold, rhenium, and glassy carbon electrodes from acidic perrhenate solutions (pH = 1.5 +/- 0.1) prepared from hydrogen peroxide and zerovalent rhenium metal is described. Cyclic voltammetry, variable angle spectroscopic ellipsometry (VASE), X-ray photoelectron spectroscopy (XPS), UV-vis spectroelectrochemistry, and electrochemical quartz crystal microbalance (EQCM) data indicate that the chemical nature of the electrodeposited rhenium species depends mainly upon the potential and supporting electrolyte. The presence of SO4(2-) as a supporting electrolyte inhibits the adsorption of perrhenate, ReO4-, at non-hydrogen adsorbing electrode materials. However, in acidic perrhenate solutions containing only protons and ReO4- anions, strong adsorption of ReO4- at potentials preceding hydrogen evolution occurs. This leads to the formation of an unstable ReIII2O3 intermediate which catalytically disproportionates to form mixed-valent rhenium films consisting of 72% ReIVO2 and 28% Re0. During the hydrogen evolution reaction (HER), hydrogen polarization causes the principle deposit to be more reduced, consisting of roughly 64% ReIVO2 and 36% Re0. Conclusively, metallic rhenium can be deposited at potentials preceding the HER at non-hydrogen adsorbing electrode materials, especially in the absence of SO4(2-) anions.     

Electrochemical deposition and characterization of NiCu coatings as cathode materials for hydrogen evolution reaction

In this study, NiCu composite coatings were electrochemically deposited on a copper electrode (Cu/NiCu) and characterized by atomic absorption spectroscopy (AAS), scanning electron microscopy (SEM) and scanning electrochemical microscopy (SECM) techniques in view of their possible applications as electrocatalytic materials for the hydrogen evolution reaction (HER). The HER activity of the prepared electrodes were studied in 1 M KOH solution by cathodic current–potential curves and electrochemical impedance spectroscopy (EIS) techniques. It was found that, the NiCu coating has a porous structure and good electrocatalytic activity for the HER in alkaline medium. The HER activity of the Cu/NiCu electrode was higher than uncoated (Cu) and Ni coated (Cu/Ni) copper electrodes. Its catalytic activity was related to the porosity as well as synergistic interaction of Ni and Cu.