Study of the electrochemical deposition of Sn-Ag-Cu alloy by cyclic voltammetry and chronoamperometry

The electrochemical deposition of Sn-Ag-Cu alloy from weakly acidic baths onto glassy carbon electrodes (GCE) was studied by cyclic voltammetry (CV) and chronoamperometry (CA). The properties of the electrodeposits were characterized by scanning electron microscopy (SEM), energy-dispersive spectrometery (EDS) and X-ray diffraction (XRD). Test results indicate that the two cathodic peaks in the CV curves, at −0.6 V and −0.85 V during the forward scan towards the negative potentials, correspond to the irreversible deposition of a solid solution of tin, silver and copper. The underpotential deposition (UPD) of Sn occurs at −0.6 V during the cathodic period and the amount of Ag and Cu in the Sn-Ag-Cu alloy decreases with increasingly negative cathodic potentials. During the forward scan, towards the positive potentials used in CV testing, cathodic peaks at −0.85 V appear in the CV curves for baths containing mixtures of tin salts and triethanolamine (TEA). This corresponds to a reduction of transient complex ions [Sn(TEA)_x]²⁺ on the surface of the cathode. Furthermore, the formation and reduction of [Sn(TEA)_x]²⁺ is a diffusion controlled process. On the surface of the GCE, the actual nucleus growth mechanism of the Sn-Ag-Cu alloy is represented by the progressive nucleation model.     

Effect of triethanolamine and heliotropin on cathodic polarization of weakly acidic baths and properties of Sn-Ag-Cu alloy electrodeposits

The effect of triethanolamine (TEA) and heliotropin (HT) on the cathodic polarization of weakly acidic baths and the properties of Sn-Ag-Cu alloy electrodeposits were investigated. Lead-free Sn-Ag-Cu solder alloy were electrodeposited in weakly acidic baths (pH 5.5) containing Sn(CH₃SO₃)₂, AgI, Cu(CH₃SO₃)₂, K₄P₂O₇, KI, hydroquinone, TEA, HT and methylsulfonic acid (MSA). The cathodic polarization of baths and the properties of electrodeposits were evaluated by Liner sweep voltammetry (LSV), scanning electron microscopy (SEM), X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transform infrared spectrometer (FT-IR) and X-ray photoelectron spectroscopy (XPS). The results indicate that HT is a main brightening agent that increases the cathodic polarization of baths and refines the grains of electrodeposits; TEA is a complexing agent for copper ions and a brightening promoter that decreases the cathodic polarization of baths and densifies the electrodeposits. The bright, compact, and smooth Sn-Ag-Cu alloy electrodeposits contain 88-95 wt% tin, 5-10 wt% silver and 0.5-2 wt% copper. Organic compounds used in the baths neither adsorb on the electrodeposits surfaces nor are included in the electrodeposits. It can be therefore concluded that the use of both TEA and HT is better than that of them either in the process of electroplating bright Sn-Ag-Cu alloy.     

Electrodeposition of zinc–nickel alloys from ammonia-containing baths

This paper describes the use of ammonia-containing baths for Zn–Ni alloy electrodeposition. Buffering properties of the ammonia/ammonium couple limit the local change in pH in the vicinity of the electrode surface caused by simultaneous hydrogen evolution. In addition, it is shown that the divalent zinc and nickel species exist in the form of Zn(NH₃) ₄ ²⁺ and Ni(NH₃) ₆ ²⁺ complexes over a large pH range. The electrochemistry of the deposition at pH 10 was investigated by galvanostatic experiments and cyclic voltammetry, and compared with deposition from ammonium chloride baths at pH 5. The Ni content in the alloys were found to be 40–60% higher from the ammonia-containing bath than from the acidic baths. Reduction of divalent ions and hydrogen evolution were shown to occur at potentials 250mV more cathodic than with baths at pH 5; the deposition mechanism may be affected by complexation of the metal cations by ammonia.     

Nucleation of Sn and Sn-Cu alloys on Pt during electrodeposition from Sn-citrate and Sn-Cu-citrate solutions

The initial stages of Sn and Sn-Cu electrodeposition from Sn-citrate and Sn-Cu-citrate solutions on Pt were studied using both current-controlled and potential-controlled electrochemical techniques. For both Sn-citrate and Sn-Cu-citrate solutions, when the current density is controlled to lower than 15 mA/cm², potentials remain almost constant which is appropriate to plate dense and uniform films. When the current density is controlled to between 25 and 35 mA/cm², potentials drop quickly initially, followed by a gradual increase to a constant value. When current density is controlled to higher than 50 mA/cm², potential oscillation happens, and significant hydrogen evolution prevents the formation of dense and continuous Sn and Sn-Cu films. A constant transition time constant indicates a diffusion-controlled process. The diffusion coefficient calculated from the Sand equation is about 3.8 × 10⁻⁶ cm²/s for the Sn-citrate solution and 4.1 × 10⁻⁶ cm²/s for the Sn-Cu-citrate solution. The morphology of both Sn and Sn-Cu deposits plated under different potentials was examined by atomic force microscopy (AFM) and the distribution of each element were analyzed using Auger imaging. Analysis of both the electrochemical results at −0.72, −1.1 and −1.5 V and AFM images for both Sn and Sn-Cu deposits at −1.1 and −1.5 V suggested progressive nucleation controlled by diffusion for both Sn and Sn-Cu electrodeposition. Tin reacted with Pt to form PtSn₄, and co-deposited with Cu to form Cu₆Sn₅ during nucleation, with more Sn forming at higher applied potentials.     

Efficient electrochemical reduction of nitrate to nitrogen on tin cathode at very high cathodic potentials

The electrochemical reduction of nitrate on tin cathode at very high cathodic potentials was studied in 0.1 M K₂SO₄, 0.05 M KNO₃ electrolyte. A high rate of nitrate reduction (0.206 mmol min⁻¹ cm⁻²) and a high selectivity (%S) of nitrogen (92%) was obtained at −2.9 V versus Ag/AgCl. The main by-products were ammonia (8%) and nitrite (<0.02%). Small amounts of N₂O and traces of NO were also detected.As the cathodic potential increases, the %S of nitrogen increases, while that of ammonia displays a maximum at −2.2 V. The %S of nitrite decreases from 65% at −1.8 V to <0.02% at −2.4 V. The kinetic analysis indicated that the formation of nitrogen and ammonia proceeds through the intermediate nitrite.The reduction follows first order kinetics for both nitrate and nitrite at more cathodic potentials than −2.4 V, while at less negative potentials the kinetics is more complicated.The %Faradaic efficiency (%FE) of the reduction at −2.9 V was about 60% initially and decreased to 22% at 40 min.A cathodic corrosion of tin was observed, which was more intensive in the absence of nitrate. At potentials more negative than −2.4 V, small amounts of tin hydride were detected.     

The characterization and bioelectrocatalytic properties of hemoglobin by direct electrochemistry of DDAB film modified electrodes

Direct electrochemistry of hemoglobin can be performed in acidic and basic aqueous solutions in the pH range 1-13, using stable, electrochemically active films deposited on a didodecyldimethylammonium bromide (DDAB) modified glassy carbon electrode. Films can also be produced on gold, platinum, and transparent semiconductor tin oxide electrodes. Hemoglobin/DDAB films exhibit one, two, and three redox couples when transferred to strong acidic, weak acidic and weak basic, and strong basic aqueous solutions, respectively. These redox couples, and their formal potentials, were found to be pH dependent. An electrochemical quartz crystal microbalance and cyclic voltammetry were used to study the in situ deposition of DDAB on gold disc electrodes and hemoglobin deposition on DDAB film modified electrodes. A hemoglobin/DDAB/GC modified electrode is electrocatalytically reduction active for oxygen and H₂O₂, and electrocatalytically oxidation active for S₂O₄²⁻ through the Fe(III)/Fe(II) redox couple. In the electrocatalytic reduction of S₄O₆²⁻, S₂O₄²⁻, and SO₃²⁻, and the dithio compounds of 2,2′-dithiosalicylic acid and 1,2-dithiolane-3-pentanoic acid, the electrocatalytic current develops from the cathodic peak of the redox couple at a potential of about −0.9 V (from the Fe(II)/Fe(I) redox couple) in neutral and weakly basic aqueous solutions. Hemoglobin/DDAB/GC modified electrodes are electrocatalytically reduction active for trichloroacetic acid in strong acidic buffered aqueous solutions through the Fe(III)/Fe(II) redox couple. However, the electrocatalytic current developed from the cathodic peak of the redox couple at a potential of about −0.9 V (from the Fe(II)/Fe(I) redox couple) in weak acidic and basic aqueous solutions. The electrocatalytic properties were investigated using the rotating ring-disk electrode method.     

Zinc electrodeposition in the presence of polyethylene glycol 20000

The influence of polyethylene glycol 20000 (PEG₂₀₀₀₀) on the mechanism of zinc deposition and nucleation was studied by voltammetry, chronoamperometry, and atomic force microscopy (AFM). The electrodeposition of zinc in an electrolytic bath containing PEG₂₀₀₀₀ occurs via two reduction processes with different energies that involve the same species, ZnCl₄²⁻: the first reduction process occurs at E_PI′c = −1.25 V, SCE, whereas the second process, which corresponds to the bulk deposition of Zn, occurs at E_PII′c = −1.6 V, SCE without significant interference from the hydrogen evolution reaction. Analysis of chronoamperograms obtained in the absence and presence of PEG₂₀₀₀₀ indicates that distinct nucleation mechanisms are involved during the initial stages of Zn deposition. In the absence of PEG₂₀₀₀₀, the transients are consistent with the model of 3D diffusion-controlled nucleation. In the presence of PEG₂₀₀₀₀, however, the transients exhibit a more complex form involving two simultaneous nucleation and growth processes: 2D instantaneous nucleation limited by the incorporation of adatoms (2D_i-li) and a diffusion-controlled 3D nucleation mechanism (3D_-dc). Characterization of the surface morphologies of the zinc deposits by AFM imaging confirmed our conclusions drawn from the electrochemical studies. SEM analysis showed that the zinc coatings obtained in the presence of PEG₂₀₀₀₀ at −1.6 V, SCE are smoother and more compact.     

Electrochemical properties of boron-carbon-nitride films formed by magnetron sputtering

The electrochemical behavior of B_1.0C_2.4N_1.0 thin film was investigated in acidic, neutral and alkaline solutions. The anodic polarization curve of the film in 1 M NaOH showed the anodic dissolution of the film. The curve of the film in 1 M HCl showed no anodic dissolution. The cathodic polarization curve in 1 M NaCl showed shift to a negative potential side, but the anodic polarization curve was the same as that of Pt. The anodic dissolution in 1 M NaOH depended on potentials, that is, no anodic dissolution was recognized in a potential range of −0.2 to 0.1 V but the dissolution rate increased with increasing potential in a range of 0.1-0.6 V. The anodic current density of the film is directly proportional to the dissolution rate at potentials higher than 0.1 V. The dissolution rate of the film was increased with increasing solution pH.     

Electrochemical investigation of electrodeposited Fe-Pd alloy thin films

In the present study, the electrodeposition of Fe, Pd and Fe-Pd alloys, in alkaline solutions, has been investigated. Using ammonium hydroxide and trisodium citrate as the complexing agents, it has been shown that the co-deposition of Fe and Pd is achieved due to diminishing the difference between the reduction potentials of these two metals. Cyclic voltammetry results clearly show that the electrodeposition processes are diffusion-controlled and the diffusion coefficients of Fe²⁺ and Pd²⁺ are 1.11 × 10⁻⁶ and 2.19 × 10⁻⁵ cm² s⁻¹, respectively. The step potential experiments reveal that nucleation mechanism is instantaneous with a typical three-dimensional (3D) growth. At low overpotentials, addition of Pd²⁺ to Fe²⁺ solution leads to a dramatic reduction in the number of nucleation sites, due to this fact that at such overpotentials, the electrodeposition behavior of Pd²⁺ governs on the overall process. The analysis of chemical composition of the electrodeposited films and the number of nucleation sites indicate that at higher overpotential, Fe²⁺ is deposited preferentially, thus the electrodeposition of iron-palladium alloys was classified as an anomalous co-deposition.     

Electrocrystallization of Au nanoparticles on glassy carbon from HClO4 solution containing [AuCl4]

The mechanism and kinetics of electrocrystallization of Au nanoparticles on glassy carbon (GC) were investigated in the system GC/1 mM KAuCl₄ + 0.1 M HClO₄. Experimental results show that the gold electrodeposition follows the so-called Volmer-Weber growth mechanism involving formation and growth of 3D Au nanoparticles on an unmodified GC substrate. The analysis of current transients shows that at relatively positive electrode potentials (E ≥ 0.84 V) the deposition kinetics corresponds to the theoretical model for progressive nucleation and diffusion-controlled 3D growth of Au nanoparticles. The potential dependence of the nucleation rate extracted from the current transients is in agreement with the atomistic theory of nucleation. At sufficiently negative electrode potentials (E ≤ 0.64 V) the nucleation frequency becomes very high and the nucleation occurs instantaneously. Based on this behaviour is applied a potentiostatic double-pulse routine, which allows controlled electrodeposition of Au nanoparticles with a relatively narrow size distribution.     

Electrochemical reduction of Zn(II) ions on l-cysteine coated gold electrodes

Zn(II) ions have been selectively bound to the l-cysteine coated gold electrode in the form of a four-coordinated complex. Voltammograms of the Zn complex on the l-cysteine coated gold electrode showed a cathodic wave at ca. 0.05 V in the pH 7.54 phosphate buffered saline. The charge transfer coefficient and rate constant for the reduction of this Zn complex were 0.65 and 0.003 s⁻¹, respectively. The complexation of Zn(II) ions with l-cysteine on the gold electrode resulted in the maximum surface coverage of the Zn complex of 0.35 nmol cm⁻² and the Gibbs energy change of −27.6 kJ mol⁻¹. The cathodic peak current, influenced by the types of the end functional groups in thiols, the preconcentration time, and pH values of the supporting electrolyte, was linear with the concentration of Zn(II) ions in the range of 5.0 nM to 5 μM with a detection limit of 2.1 nM. The proposed voltammetric method was utilized successfully to detect the concentration of Zn(II) ions in hairs.     

Electrochemical synthesis and characterization of mixed molybdenum-rhenium oxides

The electrodeposition of Mo_xRe_1−xO_y films (0.6 ≤ x ≤ 1) on indium-tin oxide (ITO) coated glass substrates from acidic peroxo-polymolybdo-perrhenate solutions is described. Trends in film growth were established as a function of potential from +0.4 V to −0.7 V vs Ag/AgCl by analyzing the composition and stoichiometry of the deposit using inductively coupled plasma mass spectrometry (ICPMS) and X-ray photoelectron spectroscopy (XPS). These experiments show that the concentration of rhenium increases linearly with the deposition potential and that the deposits are mixed-valent containing up to five different metal oxidation states (i.e., Mo^IV, Mo^V, Mo^VI, Re⁰, Re^IV). Electroanalytical techniques were used to explore the deposition mechanism, including chronocoulometry, cyclic voltammetry, spectroelectrochemistry, and electrochemical quartz crystal nanogravimetry (EQCN). At potentials positive to −0.26 V, perrhenate (Re^VIIO₄⁻) behaves as a redox mediator to accelerate the deposition of a mixed-valent molybdenum oxide, but at more negative potentials mixed molybdenum-rhenium oxides are produced.     

Investigation of the surface properties and the hydrogen evolution reaction, HER, at thermal rhodium oxide electrodes

A systematic investigation was conducted of the surface properties and the HER at electrodes of nominal composition Ti/Rh_xTi_(1−x)O_y prepared by thermal decomposition (T_cal: 500 °C; t_cal: 2 h; O₂ flux: 5 dm³ min⁻¹) from salt precursor solutions dissolved in 6.0 mol dm⁻³ HNO₃. Films were characterized ex situ by SEM, EDX, XPS and XRD and in situ by open circuit potential measurements and CV. The electrochemical behaviour was investigated by CV as function of the anodic, E_λ,a, and cathodic, E_λ,c, switching potentials showing the Rh surface oxidation states strongly depend on these experimental variables. Surface Rh-sites are reduced to metallic rhodium in the cathodic potential region while higher oxidation states (I-III) are formed at more positive potentials (E ≥ 0.5 V/RHE). Hydrogen adsorption and desorption peaks as well as a short double layer charging region are observed at intermediate potential values. The HER was investigated by Tafel coefficients and reaction order with respect to H⁺ as function of nominal Rh-content.     

Electrochemical and spectroscopic characterization of a tungsten electrode as a sensitive amperometric sensor of small inorganic ions

Cyclic voltammetry was used to investigate the electrochemical behaviour of the tungsten oxide films toward the electroreduction of BrO₃⁻, ClO₂⁻ and NO₂⁻ ions in acidic medium. The effects of the temperature, scan rate, pH, chemical composition of the electrolytic solutions, were investigated and the reduction mechanism was critically discussed.The reduction currents, evaluated in cyclic voltammetry and measured at −0.250 V versus SCE, increased linearly on increasing analyte concentration up to 20, 55 and 45 mM for nitrite, chlorite and bromate ions, respectively. The detection limits, evaluated in cyclic voltammetry, were 0.1, 0.4 and 0.7 mM for BrO₃⁻, ClO₂⁻ and NO₂⁻, respectively.The tungsten oxide film was successfully characterized as an amperometric sensor for the analytical determination of BrO₃⁻, ClO₂⁻ and NO₂⁻ ions in flowing stream. Operating under constant applied potential of −0.3 V versus Ag/AgCl the good reproducibility of the peak height and background current level during consecutive injections, indicates the absence of fouling effects and the potential applicability of the amperometric sensor for the routine analytical determination of the investigated inorganic ions. Considering the low values of the background currents (ca. 1.1 ± 0.1 μA) obtained in acidic and not deoxygenated carrier electrolyte, the tungsten sensing electrode seems to compete favourably with other common sensors for the amperometric determination of electroactive molecules under cathodic conditions.The X-ray photoelectron spectroscopy technique (XPS) was used in order to evaluate the chemical composition of the tungsten film upon electrochemical treatment in 0.1 M H₂SO₄ solution. Independently of the electrochemical treatment in acid solution, the tungsten surface electrode is generally composed by 50-60% of W⁰, 35-40% of W⁶⁺ and traces of W²⁺ oxide species.     

Electrochemical studies on gold electrodes in acidic solutions of thiourea containing gold (I) thiourea complex ions

Electrochemical studies were made of the behaviour of gold electrodes in degassed acidic solutions containing between 0.00l to 0.03 M thiourea and between 10^–5 to 10^–3 M gold(I)thiourea. At anodic overpotentials of up to 0.3 V the dissolution of gold was rapid, and nearly reached the maximum diffusioncontrolled rate. The exchange current density was greater than 10^–6 A cm^–2, and dissolution proceeded at 100% efficiency. At higher anodic potentials, thiourea was oxidized to formamidine disulphide and other sulphur-containing compounds and the dissolution of gold became partly inhibited, while the current efficiency decreased markedly.The reduction of gold(I)thiourea was diffusion-controlled at cathodic overpotentials between –0.15 to –0.35 V, after which slight inhibition was observed. Thiourea itself did not contribute to the cathodic reaction, but formamidine disulphide could be reduced on a freshly deposited gold surface; in the absence of gold(I)thiourea in the solution, the reduction of formamidine disulphide caused rapid passivation of the gold surface. In 0.01 M thiourea and 0.1 M sulphuric or perchloric acid, the diffusion coefficient of the Au(CS(NH₂)₂) ₂ ⁺ ion was 1·1 x 10^–5 cm² s^–1 at 30°C.The standard reduction potential at 30° C of the redox couple Au(CS(NH₂)₂) ₂ ⁺ ¦Au on a fresh gold surface wasE ₀=0.352 V, but on a passivated gold surface this value increased to as much asE ₀=041V.     

Silver electrocrystallization from a nonpolluting aqueous leaching solution containing ammonia and chloride

Silver electrocrystallization from aqueous solutions at pH11, pC10 and pNH₃ – 0.2, where Ag(NH₃)₂ ^– is the dominant Ag(i) species, has been studied. In spite of the complexities of this medium, the experimental results can be satisfactorily described in terms of multiple nucleation and diffusion-controlled growth of hemispherical nuclei. Nucleation rates, A, and number densities of active sites on the electrode surface, N0, were determined from potentiostatic current transients as a function of overpotential. Saturation number densities of silver nuclei on the electrode surface obtained from the A and N0 values were found to be in excellent agreement with those obtained from the direct, microscopic observation of the electrode surface. Spatial distributions of nuclei were also analysed for silver electrodeposited at different potentials. It was found that nuclei were uniformly distributed when electrodeposited at low overpotentials, whereas inhibition of nucleation close to already established nuclei occurred at higher overpotentials. From the change of the true nucleation rate with overpotential, it was found that the critical nucleus is formed by a single atom within the –100 to –300 mV over-potential range.     

Strategy for the syntheses of isolated fine silver nanoparticles and polypyrrole/silver nanocomposites on gold substrates

In this work, isolated fine silver nanoparticles and polypyrrole/silver nanocomposites with diameters of about 10 nm on gold substrates were first prepared by electrochemical methods. First, an Ag substrate was cycled in a deoxygenated aqueous solution containing 0.1 M HCl from −0.30 to +0.30 V versus Ag/AgCl at 5 mV/s with 30 scans. Subsequently the Ag working electrode was immediately replaced by an Au electrode and a cathodic overpotential of 0.2 V was applied under controlled sonication to synthesize Ag nanoparticles on the Au electrode. Then pyrrole monomers were encouragingly found to be polymerized on the deposited Ag nanoparticles. This polymerization is distinguishable from the known chemical or electrochemical one, due to the electrochemical activity of unreduced species of Ag_n⁺ clusters inside the nanoparticles. Also, this polymerization may be ascribed to the oxidizing agent of AuCl₄⁻, which is present on the Au electrode.     

Electrodeposition of CdTe thin films onto n-Si(1 0 0): nucleation and growth mechanisms

The mechanisms related to the initial stages of the nucleation and growth of cadmium telluride (CdTe) thin films on the rough face side of a (1 0 0) monocrystalline n-type silicon have been studied as a function of different potential steps that varied from an initial value of −0.200 V to values comprised between −0.515 and −0.600 V versus saturated calomel electrode (SCE). The analysis of the corresponding potentiostatic j/t transients suggests that the main phenomena involved at short times is the formation of a Te-Cd bi-layer (BL). For potentials below −0.540 V, the formation of this bi-layer can be considered independent of potential. At greater times, the mechanisms is controlled by two process: (i) progressive nucleation three dimensional charge transfer controlled growth (PN-3D)_ct and (ii) progressive nucleation three dimensional diffusion controlled growth (PN-3D)_diff, both giving account for the formation of conical and hemispherical nuclei, respectively. Ex situ AFM images of the surface seem to support these assumptions.     

Study of the oxygen electroreduction at nanostructured PtBi catalysts in alkaline medium

Nanostructured Pt_1−xBi_x/C electrocatalysts (x from 0 to 0.3) are prepared via a microemulsion method. The electroactivity of the catalysts towards oxygen reduction reaction (orr) is investigated. The following order of catalysts for electrochemical activity towards orr is obtained: Pt_0.8Bi_0.2/C > Pt_0.9Bi_0.1/C > P/C > Pt_0.7Bi_0.3/C. RDE and RRDE experiments indicate a four-electron reduction reaction mechanism in the low overpotentials region with all Pt_1−xBi_x/C electrocatalysts, whereas, at higher overpotentials a two-electron mechanism producing hydrogen peroxide co-exists with the four-electron mechanism producing water. Two Tafel slopes are obtained for all catalysts. In the low overpotentials region all Bi-containing catalysts display Tafel slopes close to −60 mV decade⁻¹, against −80 mV decade⁻¹ for pure platinum. In the high overpotentials region, the Tafel slopes are close to −120 mV decade⁻¹, except for the Pt_0.7Bi_0.3/C for which a Tafel slope close to −100 mV decade⁻¹ is observed. Results are explained in terms of protection of platinum surface from oxidation by the presence of more easily oxidizable species, leading to shift the reduction wave of 20-30 mV towards higher potentials, while the platinum surface coverage by bismuth oxides species leads to decrease the accessible platinum sites and further the orr kinetics. At last, the higher tolerance of a Pt_0.8Bi_0.2/C catalyst to the presence of ethylene glycol is demonstrate, as well as its higher performance as cathode catalyst under direct ethylene glycol solid alkaline membrane fuel cell working conditions.     

Electrodeposition of copper on Ru(0 0 0 1) in sulfuric acid solution: Growth kinetics and nucleation behavior

The electrodeposition of Cu on Ru(0 0 0 1) from 0.1 M CuSO₄/0.5 M H₂SO₄ solution has been studied by cyclic voltammetry, current-time transient measurements, and by in situ electrochemical atomic force microscopy (EC-AFM). Cyclic voltammetry measurements show that the as-prepared Ru(0 0 0 1) electrode exhibits a UPD peak, while EC-AFM data indicate a broadly terraced surface with step heights of atomic dimensions. Kinetic data show that the electrodeposition/nucleation process is not well described by 3D or 2D nucleation models. The EC-AFM data show that at potentials near the OPD/UPD threshold, Cu crystallites exhibit pronounced growth anisotropy, with lateral dimensions greatly exceeding vertical dimensions. AFM data also show that deposition at more cathodic potentials result in smaller crystallites.