Applied Deposition Potential Research Articles

Electrodeposition of Ni–Mo alloy coatings from choline chloride and propylene glycol deep eutectic solvent plating bath

Ni–Mo alloy coatings were deposited on a copper base material from a non-aqueous plating bath based on a deep eutectic solvent (DES) of choline chloride and propylene glycol in a 1:2 molar ratio containing 0.2 mol dm−3 NiCl2 · 6H2O and 0.01 mol dm−3 (NH4)6Mo7O24·4H2O. Uniform and adherent Ni–Mo deposits with a nodular morphology were obtained at all the deposition potentials investigated (from − 0.5 to − 0.9 V vs. Ag). By shifting the potential from − 0.5 to − 0.9 V, the deposition current density increased from − 0.4 to − 1.5 mA cm−2 and the overall surface roughness increased. It was also accompanied by an increase in the Mo content from ~ 7 to ~ 13 wt% in the potential range from − 0.5 to − 0.7 V. A further change in the potential from − 0.8 to − 0.9 V caused a decrease in the Mo content to ~ 10 wt% and a deterioration in the quality of the coating. For the most uniform coating, deposited at − 0.6 V and having a thickness of ca. 660 nm, the crystallite size did not exceed 10 nm. With the content of Ni (89 at.%) and Mo (11 at.%), the selected area electron diffraction (SAED) analysis allowed us to identify the cubic phase Ni3.64Mo0.36. The corrosion resistance of Ni–Mo coatings in 0.05 mol dm−3 NaCl solution generally increased during exposure of 18 h, as evidenced by ever higher polarization resistance. Finally, regardless of the applied deposition potential, low corrosion currents (in the range of 0.1–0.3 μA cm−2) have been measured for the coatings. EIS revealed that charge transfer resistances were the highest (57–67 kΩ cm2) for coatings deposited at − 0.5 V, − 0.6 V and − 0.7 V. Further increase in the deposition potential in the negative direction was unfavorable.

Evaluation of structural, magnetic and concentration dependent texture variations of electrodeposited cobalt nanowires

Anodized aluminum oxide (AAO) templates have been used to synthesize Cobalt (Co) nanowires (NWs) by employing the electrodeposition technique as a function of cobalt ions concentration. Cobalt NWs show a strong dependence on cobalt ions concentration, applied during synthesis, in with reference to their structural and magnetic properties. The Co hexagonal (HCP) phase dominates X-ray diffraction, with the (002) plane oriented perpendicular to the NW long axis with lower applied deposition potential and parallel to the NW long axis at higher Co ions concentration. The reorientation of (002) HCP plane and evolution of face-cantered cubic phase (FCC) at higher concentrations of Cobalt ions results in easy axis of magnetization is switched to the long axis of NW from parallel. Co-NWs crystalline structure and magnetic characteristics might be adjusted based on Co ion concentration during synthesis.

An analytical study on nucleation and growth mechanism of nanostructured Ni-Se coating by the chronoamperometry and pulse potential techniques

The current paper aimed to investigate the mechanism of Ni-Se electrodeposition and contribute a comprehensive understanding of Ni-Se deposition by pulse potential technique. Firstly, electrochemical mechanisms including the reactions and nucleation mechanism of Ni-Se on glassy carbon electrode were studied using cyclic voltammetry (CV) and chronoamperometry (CA) techniques, respectively. Moreover, to investigate the nucleation and growth mode influenced by different concentrations and applied deposition potential, experimental results were fitted into Bewick 2D nucleation and Scharifker-Hills 3D nucleation models. Current transient curves showed the electrodeposition of Ni-Se phase follows both the 2D nucleation and 3D progressive nucleation and diffusion-controlled growth. This work reports how the deposition of Ni-Se nuclei by pulse potential method on different substrates and the dependence of pulse parameters on the nucleation, growth, morphology, and stoichiometry of the nanostructured Ni-Se coating.

Rapid electrochemical-biosensor microchip platform for determination of microalbuminuria in CKD patients

An electrochemical-biosensor (EC-biosensor) microchip consisting of screen-printed electrodes and a double-layer reagent paper detection zone impregnated with amaranth is proposed for the rapid determination of microalbuminuria (MAU) in human urine samples. Under the action of an applied deposition potential, the amaranth is adsorbed on the electrode surface and the subsequent reaction between the modified surface and the MAU content in the urine sample prompts the formation of an inert layer on the electrode surface. The inert layer impedes the transfer of electrons and hence produces a drop in the response peak current, from which the MAU concentration can then be determined. The measurement results obtained for seven artificial urine samples with known MAU concentrations in the range of 0.1–40 mg/dL show that the measured response peak current is related to the MAU concentration with a determination coefficient of R2 = 0.991 in the low concentration range of 0.1–10 mg/dL and R2 = 0.996 in the high concentration range of 10–40 mg/dL. Furthermore, the detection results obtained for 82 actual chronic kidney disease (CKD) patients show an excellent agreement (R2 = 0.988) with the hospital analysis results. Overall, the results confirm that the proposed detection platform provides a convenient and reliable approach for performing sensitive point-of-care testing (POCT) of the MAU content in human urine samples.

Nucleation, Pattern Development, and Fidelity in the Photoelectrodeposition of Se-Te Nanostructures

The electrochemical growth of Se-Te under polarized illumination results in anisotropic, highly-ordered lamellar nanostructures, tunable by input wavelength. This spontaneous growth occurs at room temperature, in an isotropic solution, with no templating or chemically-directing agents, and with mW-cm-2 illumination intensity with no requirement for coherency. The deposition process is compatible with a wide variety of conductive substrates and can be performed over large areas of unpatterned substrates. However, pattern fidelities in these films are generally low. Improving the potentially broad applicability of this patterning method requires an understanding of pattern development and of factors contributing to the long-range order of films deposited through this phenomenon.Methods of quantifying pattern fidelity have been developed using Fourier-transform (FT) analysis of large-area images of photoelectrodeposited Se-Te films. Nominally identical illumination conditions during the deposition of Se-Te on crystalline (111)-oriented Si substrates doped degenerately with either p- or n-type dopants produced a variation in the morphology of Se-Te films. Films deposited on p+-Si generally displayed much less defective patterns, with a higher degree of anisotropy and a more well-defined pattern period versus films deposited on n+-Si. These results are attributed to the energetics at the dynamic junction formed by growing Se-Te and the Si substrate.Analysis of film morphologies at early levels of mass addition to growth substrates elucidate the mechanism by which junction energetics affect resulting film morphologies. Higher nucleation densities are generally observed under conditions that produced Se-Te films with relatively higher pattern fidelities. Control of pattern fidelity by control of nucleation density, through substrate choice and tuning of applied deposition potential, is demonstrated.

Electrochemically grown vertical CdTe nanowire arrays on a flexible/transparent substrate

Vertical cadmium telluride (CdTe) nanowires were grown on flexible/transparent substrates by sputtering ITO and aluminum thin films on Parylene substrates, anodizing aluminum to form porous alumina, followed by electrodeposition of CdTe nanowires from ITO seed layer. The pore size of anodized alumina was controlled by oxalic acid concentration and applied voltage. The composition of CdTe nanowires were tuned by adjusting applied deposition potential and solution composition. I-V characteristics of a single 50 nm in diameter CdTe nanowire was examined using a conductive atomic force microscope (CAFM) at room temperature which indicates that the electrical resistivity of electrodeposited CdTe nanowires are similar to thin-film counterpart.

A Comparative Study on Microstructures, Magnetic Features and Morphologies of Ternary Fe–Co–Ni Alloy Thin Films Electrochemically Fabricated at Different Deposition Potentials

Electrochemically fabricated ternary Fe–Co–Ni alloy thin films with different chemical compositions were obtained at different deposition potentials. An increase in the deposition potential increased the Ni content while it decreased the Co and Fe contents in the film structure. An anomalous co-deposition behaviour was also studied and the anomalous order of co-deposition was found to be Fe–Ni > Co–Ni > Fe–Co irrespective of deposition potential. Structural characterizations confirmed the presence of single face-centred cubic (fcc) phase structure with [111] preferred crystallographic orientation for all films. The size of the crystallites and the texture degree increased with increasing applied deposition potential. Smaller globular particles occurred on the surface structure of the film fabricated at higher deposition potentials compared to those grown at lower deposition potentials. A decrement detected in the coercive field with increasing applied deposition potential was related to the variations occurred in the chemical composition and the particle size.

Electrodeposition of Cu–Ga precursor layer for CuGaS2 solar energy thin film from alcohol solution

CuGaS2 thin film is fabricated with electrochemical deposition of Cu–Ga alloys from alcohol solution to eliminate the interference of hydrogen evolution reaction (HER). The process involves electrodeposition of Cu–Ga precursor on molybdenum substrate and subsequential annealing in sulfur vapor. The formation of CuGa2 alloy in precursor is observed and pure ternary chalcopyrite CuGaS2 phase in good polycrystalline structure without secondary phase is obtained after thermal treatment. The influence of the applied deposition potential on the crystalline phase, morphology, compositions, and carrier concentration of the films were investigated. The results show that an optimum choice of electrodeposition potential is necessary to obtain a pure crystallized CuGaS2 thin film. A lower absolute deposition potential results in a higher Cu/Ga ratio and the emergence of CuS secondary phase after annealing in sulfur atmosphere. The crystal size of the formed CuGaS2 phase with thermal annealing process increases with the positive shift of deposition potential. Impedance spectroscopy test demonstrates the semiconductor property of the synthesized CuGaS2 polycrystalline thin films are all p-type. The carrier density of the obtained CuGaS2 thin films increases with the negative shift of deposited potential.

Analysis of electrodeposition parameters influence on cobalt deposit roughness

Over the last years an increased interest has been seen in the electrodeposition of cobalt and cobalt alloys. An essential challenge in the electrodeposition of cobalt is to control the structure and morphology which, in turn, depends on the preparation conditions. The work presents an assessment of the influence of parameters of cobalt deposition in potentiostatic conditions on the structure and morphology of the obtained deposits surface. The level of development of electrocatalytically deposited cobalt layers was examined through microscope methods with the use of the atomic force microscope. Additionally, the samples structure was analysed using X-radiation.The conducted tests allow drawing the following conclusions. The level of surface development does not depend on the applied potential at which deposition of cobalt is carried out. Deposition at low potentials result in creating, on the surface the mixture of metallic cobalt and hydroxides with high level of surface development. High concentration of cobalt ions in the solution result in obtaining close values of the surface development level irrespective of the applied deposition potential.

AGNES at vibrated gold microwire electrode for the direct quantification of free copper concentrations

The free metal ion concentration and the dynamic features of the metal species are recognized as key to predict metal bioavailability and toxicity to aquatic organisms. Quantification of the former is, however, still challenging. In this paper, it is shown for the first time that the concentration of free copper (Cu2+) can be quantified by applying AGNES (Absence of Gradients and Nernstian equilibrium stripping) at a solid gold electrode. It was found that: i) the amount of deposited Cu follows a Nernstian relationship with the applied deposition potential, and ii) the stripping signal is linearly related with the free metal ion concentration. The performance of AGNES at the vibrating gold microwire electrode (VGME) was assessed for two labile systems: Cu-malonic acid and Cu-iminodiacetic acid at ionic strength 0.01 M and a range of pH values from 4.0 to 6.0. The free Cu concentrations and conditional stability constants obtained by AGNES were in good agreement with stripping scanned voltammetry and thermodynamic theoretical predictions obtained by Visual MinteQ. This work highlights the suitability of gold electrodes for the quantification of free metal ion concentrations by AGNES. It also strongly suggests that other solid electrodes may be well appropriate for such task. This new application of AGNES is a first step towards a range of applications for a number of metals in speciation, toxicological and environmental studies for the direct determination of the key parameter that is the free metal ion concentration.

Electrodeposition of ZnO thin films on conducting flexible substrates

In this work, we studied the DC electrochemical deposition of zinc oxide (ZnO) thin films on a conducting and flexible substrate, for their application in energy harvesting piezoelectric nanodevices. The deposition process was performed by varying the zinc nitrate concentration (c) in the electrolyte, its temperature (T), and the applied deposition potential (V), and subsequently tracing the influence of such parameters on the morphology (analyzed by scanning electron microscopy), crystallography (X-ray diffraction), and thickness (using the deposition current transient curves) of the ZnO thin films. The variation of the electrodeposition parameters led to the formation of different micro- and nano-structures, such as flat layers, microflowers, nanospheres, webs, and microramifications. Furthermore, the analysis of the deposited charge (by integrating the deposition current transients) illustrated an increase in the deposition rate with the increase of T and c, and a decrease of V. Finally, the maximum ZnO film thickness (~5 \(\upmu {\mathrm{m}}\)) was obtained for T = 80 °C, c = 0.1 M, and V = −1.5 V. This study provides us important tools to tune the electrochemical growth of ZnO thin films.

Influence of the electrodeposition potential on the crystallographic structure and effective magnetic easy axis of cobalt nanowires

Cobalt nanowires (NWs) have been synthesized by electrodeposition inside the pores of anodized aluminium oxide templates, at different values of applied deposition potential.

Optimization of electrochemical step deposition for bioceramic hydroxyapatite coatings on CoCrMo implants

Abstract CoCrMo metallic implants were coated with a bioceramic hydroxyapatite layer using a modified step electro-deposition at room temperature. Response Surface Methodology (RSM) and Central Composite Design (CCD) were used to model and optimize the step deposition parameters, such as initial potential, scan rate and peak potential. Interactions between step deposition parameters and in vitro corrosion performance of the coatings were modeled by response surface plots. Predicted and experimental values were fitted with high accuracy. The effects of the step deposition parameters were evaluated within the limits of lowest applied potential (− 0.03 to − 1.17 V), scan rate (3.43–116.57 mV/s) and highest applied deposition potential (− 1.08 to − 1.92 V). A 5-level-3-factor experiment plan was used to optimize step deposition parameters. Optimum conditions for the modified step deposition parameters were determined as initial potential of − 0.76 V, peak potential of − 1.67 V and scan rate of 59.33 mV/s.

Morphologically controlled electrodeposition of fern shaped Bi2Te3 thin films for photoelectrochemical performance

Abstract Bismuth telluride (Bi2Te3) thin films have been proved to be important materials for thermoelectric application. Rapid development of photovoltaic materials has raised new hopes due to directly converting sun light to electricity. We report here a simple electrochemical synthesis route for the preparation of well-defined Bi2Te3 nanostructures for photoelectrochemical solar cell application. Classification of crystal structure, surface morphology and elemental composition of resulting deposits were methodically characterized by X-ray diffraction (XRD) pattern, Raman spectroscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and its photoelectrochemical performance (PEC). The potential range and electrochemical reactions relevant to the growth of Bi2Te3 thin films were studied by cyclic voltammetry (CV). Furthermore, the influence of deposition variables such as applied deposition potential and effect of different surfactants (cationic, anionic and non-ionic) on morphology, crystal orientation associated with the film growth and photoelectrochemical performance were investigated systematically. The photoelectrochemical conversion efficiency recorded for Bi2Te3 is 0.083%.

Electroassisted codeposition of sol-gel derived silica nanocomposite directs the fabrication of coral-like nanostructured porous gold.

Herein, we report on a one-step coelectrodeposition method to form gold-silica nanocomposite materials from which high surface area nanostructured gold electrodes can be produced. The as-prepared Au-SiO2 films possess an interconnected three-dimensional porous framework with different silica-gold ratios depending on the deposition solutions and parameters. Chemical etching of the nanocomposite films using hydrofluoric acid resulted in the formation of nanostructured porous gold films with coral-like structures and pores in the nanometer range. The cross-linkage of the gold coral branches resulted in the generation of a porous framework. X-ray photoelectron spectroscopy confirms the complete removal of silica. Well-controlled surface area enhancement, film thickness, and morphology were achieved by manipulating the deposition parameters, such as potential, time, and gold ion and sol-gel monomer concentrations in the deposition solution. An enhancement in the surface area of the electrode up to 57 times relative to the geometric area has been achieved. The thickness of the as-prepared Au-SiO2 nanocomposite films is relatively high and varied from 8 to 15 μm by varying the applied deposition potential while the thickness of the coral-like nanostructured porous gold films ranged from 0.22 to 2.25 μm. A critical sol-gel monomer concentration (CSGC) was determined at which the deposited silica around the gold coral was able to stabilize the coral-like gold nanostructures, while below the CSGC, the coral-like gold nanostructures were unstable and the surface area of the nanostructured porous gold electrodes decreased.

Influence of the Electrodeposition Cathodic Potential on the Composition and Magnetic Properties of CoNi Nanowires

Ordered hexagonal arrays of Co (x)Ni (1-x) nanowires (NWs) with different content of cobalt (0.35 < x < 0.75), were successfully fabricated by a potentiostatic electrodeposition technique inside anodic aluminum oxide (AAO) templates. The CoNi NWs were electrodeposited using only one electrolyte bath and tuning the Co% by the applied deposition potential. The systematic study of the morphology, chemical composition and magnetic properties of the CoNi NW arrays was performed. The obtained results unambiguously demonstrated the influence of the Co content on the magnetic properties of CoNi NWs. The Co% was found to decrease when increasing the applied cathodic potential and the coercivity of the CoNi NWs linearly increased with the Co%. The magnetic texture of the fabricated NW arrays was found lower for smaller Co concentrations, which was in good agreement with the squareness results.

Electrodeposition of Cu-Ga Precursor Layer from Deep Eutectic Solvent for CuGaS2 Solar Energy Thin Film

CuGaS2 solar energy thin film is fabricated with electrochemical deposition of precursor from deep eutectic solvent (DES) based on choline chloride and urea (commercially known as Reline) to eliminate the interference of hydrogen evolution reaction (HER). The process involves electrodeposition of Cu-Ga precursor on molybdenum substrate from Reline and subsequential annealing in sulfur vapor. The formation of CuGa2 alloy in precursor is observed and pure ternary chalcopyrite CuGaS2 phase in good polycrystalline structure without secondary phase is obtained after thermal treatment. The influence of applied deposition potential on the crystalline phase, morphology, compositions and carrier concentration of the films were investigated. The Cu/Ga ratio decreases with decreasing the deposition potential benefiting the formation of a pure crystallized CuGaS2 thin film. A relative positive deposition potential results in a larger crystalline size benefitting the photoelectrical conversion. Impedance spectroscopy test demonstrates the semiconductor property of the synthesized CuGaS2 polycrystalline thin film is p-type and the carrier concentration increases with negative shift of deposition potential.

Preparation of CdTe thin film by electrodeposition in butyl methyl imidazolium bath at 80 °C

CdTe thin films have been prepared on FTO substrates by eletrochemical deposition in a butyl methyl imidazolium chloride bath at 80°C potentiostatically at three different applied potentials. The electrodeposition process ensures the underpotential deposition of Cd on Te coated FTO substrate. CdTe thin film was grown at a relatively higher growth rate which resulted a typical thickness of 2.7μm for a deposition time of 1h at an applied deposition potential of −1.45V. The XRD pattern indicates the formation of cubic CdTe phase with zincblende structure. The Cd to Te ratio of the film can be nicely tuned in the range of 0.8–2.27 by the selection of deposition potential. The film deposited at a potential of perfect stoichiometry (−1.45V) shows interconnected clusters with an average size in the range of 40–100nm. The formation of CdTe cubic phase is also ascertained by the microdomain Raman analysis. Hot probe analysis indicates the P-type behavior of the CdTe film. The band gap energy of the CdTe film is found as 1.44eV from the UV–Vis measurements. A photoelectrochemical cell with the configuration: CdTe (0.5cm2) thin film |0.1M K2Sx(pH-9.2) |Pt (2cm2) has been constructed with the electrochemically deposited CdTe thin film. The photocurrent measurement under chopped light illumination shows an onset potential of 1V (w.r.t. satd. Calomel) for cathodic photocurrent. The onset potential for the cathodic photo current generation has been complemented by the flat band potential of 0.93V (w.r.t. satd. Calomel) from the Mott Schottky measurement in the same electrolyte.

Evolution of surface roughness parameters and microstructure in two-phase nanocrystalline Co–Cu films electrodeposited onto ITO coated glass substrates at different deposition potentials

In the present research, we have studied the effect of deposition potential on the film composition, structural, and morphological properties of the electrodeposited Co–Cu thin films grown onto indium tin oxide coated glass substrates. For this purpose, the properties of the films were analyzed by means of X-ray diffraction, energy dispersive X-ray spectroscopy (EDX), and atomic force microscopy (AFM) characterization techniques. Structural characterizations showed that all of the Co–Cu films consist of hexagonal close-packed (hcp) Co and face-centered cubic (fcc) Cu phases. The hcp Co (002)/fcc Cu (111) peak intensity ratio was found to increase as the deposition potential decreased towards more negative values. An increase in the Co content in the Co–Cu films was observed as the applied deposition potential was made more negative according to EDX analysis. The decrease of the applied deposition potential towards more negative values also induced a decrease in the average crystallite sizes of both Co and Cu particles. AFM study indicated that a granular structure of the electrodeposited Co–Cu films regardless of deposition potential. As the applied deposition potential was made more negative, the surface roughness and particle size decreased considerably. Besides, two additional roughness parameters, surface kurtosis and the surface skewness were also obtained and discussed by means of the obtained results under the study.

Fabrication and magnetic properties of La-X (X = Co, Ni, and Fe) nanotube arrays prepared by electrodeposition methods

Well-ordered La-X (X = Co, Ni and Fe) nanotubes, with the average diameter of ∼200 nm, wall thicknesses of ∼40 nm, have been fabricated into anodized aluminum oxide template by potentiostatic electrodeposition method. Various composition of La-X nanotubes were obtained by tuning the applied deposition potential. Magnetization measurements reveal that doped La could enhance the coercivity (Hc) of La-X nanotubes and their easy axis is perpendicular to the nanotube axis. There is a transition from the curling to transverse mode with increase of angle. Temperature dependent magnetization indicates the existence of superparamagnetic nanoparticles and that the surface effect results in the increase of saturation magnetization (Ms) at low temperature. Abnormal behavior of temperature dependent Hc may result from thermal excitation, magnetoelastic anisotropy, as well as oxide layer of nanotube inner surface induced coupling. These one-dimensional rare-earth transition metal nanostructures could have potential applications in novel spintronics device, ultra-small magnetic media, drug delivery, or other nanodevice.