Electrodeposition Conditions Research Articles

Direct Correlations among the Grain Size, Texture, and Indentation Behavior of Nanocrystalline Nickel Coatings

By using nc-Ni coatings as a model system, systematic experiments were designed to evaluate the interaction between the microstructural and mechanical properties tailored by electrodeposition conditions. A direct correlation between grain size and texture was established for the first time. The grain size of the (111) crystalline plane decreases with the texture coefficient (RTC) regardless of the process conditions, and that of the (220) plane has different trends. Then, a peculiar phenomenon is revealed that the dependence of hardness on grain size is accurately described by the Hall-Petch relationship when changing the temperature or pH, but with different slopes, while it deviates from such a relationship with changing current density, denoting more underlying mechanisms related to texture. Finally, a surprising degree of influence of texture on hardness and elastic modulus is also presented, with the overall trend of hardness increasing with texture; and when the RTC of (111) exceeds 40%, the elastic modulus increases with texture, implying a fundamental relationship between modulus and texture. Texture predominates over the other factors on the elastic modulus, revealing the importance of elastic anisotropy. Significantly, the present work suggests a useful tailoring routine to fabricate high quality nc-Ni coatings with the desired structure and mechanical properties.

An improved strategy for transferring and adhering thin nanoporous alumina membranes onto conducting transparent electrodes for template assisted electrodeposition of high aspect ratio semiconductor nanowires with increased optical absorption

This article presents a new method for transferring and enhancing the adhesion of thin nanoporous alumina (NPA) membranes onto non-atomically flat substrates like fluorine-doped tin oxide (FTO) coated glass. The study reports use of glycerol as an additive to reduce the brittleness of the polystyrene filler that was used to fill the pores of the NPA membrane. Additionally, a new reflux-based method is reported here for the complete removal of the polystryrene filler from the porous channels of alumina. The adhesion between an NPA membrane and an underlying electrode was enhanced by electrodepositing a thin (∼40 nm) intermediate layer of the conducting polymer polyaniline (PANI). The PANI layer acts as an efficient electrostatic adhesive between the NPA and the conducting glass electrode and ensures ultra-strong adhesion of the NPA membrane, which can survive the harsh conditions of CdTe nanowire electrodeposition (60 °C temperature and an acidic electrolyte) without delamination for 30 min. The resulting nanowires clearly templated the structure of NPA and displayed free-standing nanowires over a large area with a diameter of around 60 nm, a length of approximately 2.8 μm (aspect ratio ∼47) and an areal density of 5.9 × 1012 nanowires cm−2. Total optical absorption measurement on the free-standing CdTe nanowires exhibited a 45% enhancement over a wavelength range of 350–1400 nm as compared to a CdTe planar thin film of same thickness.

Improvement of nickel nanocomposite coatings by combining zinc-doped TiO2 nanoparticles

Pure nickel and compound of nickel coatings (Ni-TiO2 and Ni-Zn/TiO2) were coated on the steel material using Watts bath with the electrodeposition conditions. Effect of the nanoparticle type and current density on the coating structure, surface morphology of the coating, hardness of the coating, and the corrosion properties of the coatings are presented. Phase and elemental analysis of the coatings were carried out by XRD and EDS techniques, respectively. SEM was used to investigate the surface morphology of the coatings, and Vickers microhardness values were measured to determine the hardness variation of the coatings. NaCl solution (3.5 wt%) was used to evaluate the corrosion properties of the coatings by the potentiodynamic polarization tests. Corrosion current density of 2.890 μA/cm2 for pure nickel coating was improved to 0.379 μA/cm2 by the coating of Zn-doped TiO2 nanoparticles at the 7A/dm2 current density. Microhardness of the Zn-doped TiO2 coating was improved compared to the pure Ni coating.

Glycerol Effect on the Corrosion Resistance and Electrodeposition Conditions in a Zinc Electroplating Process

Zinc electrodeposition is an economical process of Zn coating compared to conventional galvanic process. The galvanizing process is used in various industrial sectors to protect ferrous alloys during the corrosion process. In buildings, the galvanizing process is widely used to coat mortar protective screens. The electrodeposition of zinc has a relatively low cost compared to other coating materials for the same purpose; however, its corrosion resistance is lower than that of most protective deposits. This study evaluated the effect of adding glycerol to the electrodeposition bath on the corrosion resistance, deposition efficiency, morphology and microstructure of the zinc electrodeposit in concentrations ranging from 0.03 to 0.82 M. The electrodeposition was performed on carbon steel AISI 1020 with a current density of 10 mA.cm-2. The electroplating solution composition was 0.10 M ZnCl2, 2.80 M KCl and 0.32 M H3BO3. Electrodeposition time was 17.56 min, 5 µm thick coating, equivalent to the mass of 7.166E-3 g of zinc on the steel surface. Evaluation of the corrosion resistance was performed by means of the electrochemical tests of Anodic Voltammetry, Potentiodynamic Polarization and Electrochemical Impedance Spectroscopy (EIS) as well as Weight Loss tests in NaCl 0.5 M in 4 (four) different period of immersion. The morphology and microstructures of electrodeposited were analyzed using the techniques of Scanning Electron Microscopy (SEM) and Spectrometry X-Ray Diffraction (XRD). The presence of glycerol in the electrodeposition bath decreased the deposition efficiency; however, it increased corrosion resistance and promoted the formation of more compact and refined electrodeposited coatings. Moreover, the results showed that the corrosion rate does not vary linearly with the addition of glycerol.

Optimization of Electrolysis Conditions for Ti Film Electrodeposition from Water-Soluble KF–KCl Molten Salts

Optimized conditions for Ti film electrodeposition were investigated in water-soluble KF–KCl (45:55 mol%) molten salt at 923 K. K3TiF6 was prepared in the melt via a comproportionation reaction between K2TiF6 and Ti sponges. The K3TiF6 solubility was determined to be 1.48 mol%. Galvanostatic electrolysis was conducted on Ni plate substrates at various K3TiF6 concentrations (0.28, 0.70, and 1.43 mol%) and current densities (25–150 mA cm−2). Surface and cross-sectional scanning electron microscopy observations showed that adherent, compact, and smooth Ti films were obtained at higher K3TiF6 concentrations and lower current densities. A corrosion test was conducted for the Ti-coated Ni plate using linear sweep voltammetry, which showed that the Ti films have no cracks or voids.

Chip-Scale Electrodeposition and Analysis of Poly(3,4-ethylenedioxythiophene) (PEDOT) Films for Enhanced and Sustained Microfluidics Using DC-Redox-Magnetohydrodynamics

Redox-magnetohydrodynamics (R-MHD) microfluidics precisely manipulates fluid flow through strategic placement/activation of electrodes and magnetic fields. This paper evaluates various conditions of potentiodynamic electrodeposition of poly(3,4-ethylenedioxythiophene) (PEDOT) films on chip-based, gold electrodes to attain maximum current and charge density, which correlate directly to R-MHD pumping speed and duration in a single direction, respectively. Electrodeposition of PEDOT was controlled by cyclic voltammetry (CV) (5, 50, and 100 mV/s) in propylene carbonate (PC) solutions of monomer and TBAPF6 or LiClO4 electrolyte. The maximum charge is directly proportional to cycle number and inversely proportional to scan rate (i.e. time spent oxidizing monomer). Thicker and rougher films formed from PC:TBAPF6, compared to PC:LiClO4. CV, chronoamperometry (CA), chronopotentiometry, and impedance spectroscopy assessed the electrochemical performance of films in aqueous electrolytes. The maximum current during CA in a given aqueous electrolyte for PEDOT films was independent of electrodeposition parameters and thickness and increased linearly with ionic strength. A three-stage model describes the oxidative response of thick PEDOT films. R-MHD fluid speeds and pumping durations at 0.37 T in 780-μm-deep phosphate-buffered saline were 50 μm/s and 210 s at 50 μA and 820 μm/s and 9 s at 800 μA, respectively, between parallel-band-electrodes, modified with the thickest films.

Influence of the Conditions for Obtaining Coatings on the Structure and Properties

The paper considers the change in the mechanical and performance properties of galvanic coatings obtained under various electrodeposition and annealing operating conditions. It also shows the influence of the structure on the properties. The graphs of the dependence of the change in corrosion rate on the annealing temperature are given.

Effect of Morphology and Surface Modification of Silica Nanoparticles on the Electrodeposition and Corrosion Behavior of Zinc-Based Nanocomposite Coatings

This study mainly reports on the co-electrodeposition of solid and mesoporous silica (SiO2) particles into zinc-matrix composite coatings. Different morphologies of SiO2 nanoparticles, i.e. solid and mesoporous (MPS), were co-electrodeposited with zinc under different electroplating conditions including nanoparticle concentration and deposition current density and the composite coating micro-hardness, internal microstrain, surface roughness, and corrosion rate were investigated. An optimized electrodeposition condition at a current density of 17.5 A/cm2, and a concentration of silica and/or MPS of 1 g/l was determined. Results reveal that the crystallite size, micro-hardness, internal microstrain, roughness, and corrosion properties depend on the amount of electrodeposited silica and MPS incorporated into the zinc-matrix. It was observed that silica nanoparticles are more difficult to co-deposit than MPS, where they develop rougher surfaces, lower micro-hardness and corrosion resistance. However, composite coatings produced with silica and MPS particles surface-modified by 3-mercaptopropyltrimethoxysilane (MPTMS;-SH) exhibited higher corrosion resistance. It was shown that the corrosion resistance decreases in the order: of Zn-MPS-SH > Zn-SiO2-SH > Zn-MPS > Zn-SiO2.

Electrochemical growth of ZnO photonic crystals

ZnO films have been prepared by cathodic electrodeposition at room temperature using aqueous and non-aqueous zinc acetate electrolytes with a complexing agent for further application in optoelectronic devices. Influence of electrodeposition conditions on homogeneity and continuity of the films is discussed including the role of Trilon B as a complexing agent in grain size decrease and ensure adherence to ITO glass substrates. The annealing temperature has been optimised according to TG-DTA MS and XRD data. All ZnO opals have wurtzite-type structure and morphology of closed-packed round-shaped particles or very thin flakes forming porous sponge-like architecture. ZnO opal films with artificial microporous architecture have been synthesised using a polystyrene opal matrices as templates. Photoluminescence spectra of the ZnO coverages have shown more complex spectra for precipitates sedimented from aqueous baths than from DMSO electrolytes, most likely, because of different characteristic intrinsic defects.

Reduction of impurity contents in aluminum plates electrodeposited from a dimethylsulfone-aluminum chloride bath

High productivity and bath stability of electrodeposition for Al and its alloys from a dimethylsulfone (DMSO2)-aluminum chloride bath are highly desirable characteristics for a wide range of critical applications. However, a long-standing problem for such electrodeposits is S and Cl contamination, which results in limited ductility. In this study, we explored a reduction method for S and Cl in Al electrodeposits from a DMSO2 bath to facilitate plastic elongation of the electrodeposited Al. For 2–5:10 M ratios of aluminum chloride to DMSO2, tailoring the conditions of electrodeposition decreased the S and Cl contents to ∼0.2 at%. The addition of various metal salts revealed that gallium chloride further reduced the S and Cl contents to less than 0.1 at%. This reduction permitted the electrodeposited Al–Ga alloys to exhibit plastic elongation in tensile tests. Based on the results of experiments and first-principles calculations, we discuss the role of Ga in the growth mode of electrodeposits and its effect on grain boundary cohesion. Thus, we elucidate the mechanisms for realizing high strength and ductility in electrodeposited Al alloys.

Electrodeposited cobalt hydroxide in expanded carbon graphite electrode obtained from exhausted batteries applied as energy storage device

This paper describes the preparation and characterization of CG/Co(OH)2 electrode obtained by electrodeposition of cobalt hydroxide on expanded carbon graphite electrode (CG) for potential application as energy storage devices. The CG electrodes used in this work were obtained from exhausted batteries. Firstly, the CG electrode was submitted to an anodic polarization at 2 V in H2SO4 solution, in order to increase the active surface area at different times. Thereafter, the electrodeposition of the Co(OH)2 was carried out by applying different reduction potentials over different times in order to optimize the electrodeposition process. Scanning electron microscopy, X-ray diffraction and Raman spectroscopy results confirmed the expansion of the bare CG and the Co(OH)2 electrodeposition. Cyclic voltammetry, galvanostatic charge/discharge curves and electrochemical impedance spectroscopy were used to evaluate the electrochemical performance of the modified electrode. It was observed that the parameters of the modification process affect the morphology of the electrodeposited cobalt hydroxide. The best performance was found for the CG/Co(OH)2 modified electrode obtained by CG expanded during 750 s, followed by the electrodeposition conditions of −1.25 V during 250 s, presenting a capacitiy of 3.4 C cm−2 in an applied current density of 1.0 mA cm−2. In addition, this modified electrode also presented a retention capacity of 91% after 1400 cycles.

Single-step pulsed electrodeposition of calcium phosphate coatings on titanium for drug delivery

Metallic implants have some limitations related to bioactivity and bacteria colonization leading to infections. In this regard, calcium phosphate coatings can be used as carrier for drug delivery in order to improve the mentioned drawbacks. The present work proposes the introduction of an antibacterial agent in the course of a pulsed and reverse pulsed electrodeposition. Calcium phosphate coatings were prepared in 30 min using different pulse waveforms (unipolar-bipolar), current densities (2–5 mA/cm2) and temperatures (40–60 °C). Mechanical stability of the as-coated surfaces was studied in order to select the optimal electrodeposition conditions. Subsequently, selected coatings were loaded with an antiseptic agent, chlorhexidine digluconate (CHX), via a single-step co-deposition procedure. CHX concentration added to the electrolyte was adjusted to 3 mM based on the antibacterial efficacy of the loaded coatings evaluated in vitro with Staphylococcus aureus and Escherichia coli bacteria strains. Whereas the same chlorhexidine concentration was added to the electrolyte, results showed that the amount of CHX loaded was different for each condition while release kinetics was maintained. The results of this work demonstrate that a pulsed co-deposition strategy has great potential to modulate local delivery of antibacterial agents such as chlorhexidine digluconate, which may prevent early phase infections of metallic implants after insertion.

A Novel Electrochemical Sensor Based on Printex L6 Carbon Black Carrying CuO/Cu2O Nanoparticles for Propylparaben Determination

AbstractThe paper reports the development of a new sensor based on Printex L6 (CPL6) carbon black modified with copper oxides (CuO/Cu2O) nanoparticles and its application towards the determination of Propylparaben (PP). In fact, it is the first report of its kind in the literature. The sensor was produced through the dispersion of CPL6 in dimethylformamide on glassy carbon electrode surface followed by CuO/Cu2O electrodeposition. The conditions of electrodeposition investigated included time and solution concentration of Cu (II). Morphological, structural and electrochemical characterizations of the sensor were performed. Under optimal conditions, wide linear range (1.0 to 35.0 μmol L−1) was obtained in the detection of PP. The detection limit obtained was 0.46 μmol L−1 (S/N=3). The CuO/Cu2O‐CPL6/GCE sensor was found to be as sensitive as the high performance liquid chromatography in the determination of PP in both cosmetic and river water samples, in addition to being reproducible and stable.

The effect of the deposition conditions on the structure, composition and morphology of electrodeposited cobalt materials

The surface morphology, microstructure and thickness of electrodeposited cobalt films on gold was studied using scanning electron microscopy with chemical analysis, cycling voltammetry and extended X-ray absorption fine structure. The results show that all the details of the electrodeposition conditions such as solution (chloride, nitrate and sulfate bath), concentration, time of deposition and temperature substantially influence film growth. Deposition in nitrate solution results in different morphology and atomic structure than in sulfate or chloride solutions. Further studies, using CoCl2, showed that the growth of the cobalt layer follows a potential law with increasing concentrations or time of deposition. In both cases, similar morphologies are obtained. The influence of bath temperature on cobalt deposition was also investigated, showing an exponential increase of cobalt layer thickness with temperature. Furthermore, the opportunity to synthesize nanostructured Co films with tailored lattice parameters are discussed.

Effect of bath composition and pulse electrodeposition condition on characteristics and microhardness of cobalt coatings

Abstract Nanocrystalline cobalt coatings were produced from cobalt sulfate based electrolytes by using pulse current electrodeposition technique. The effects of bath composition and electrodeposition condition on current efficiency, morphology, structure and hardness of the coatings were investigated and the optimum deposition condition was determined. It was found that increment of cobalt sulfate concentration and sodium dodecyl sulfate (SDS) concentration in the bath had a negligible effect on microhardness of the coatings, while they were effective on electrodeposition current efficiency. Adding saccharin to electrodeposition bath decreased crystallite size of hexagonal close-packed (hcp) cobalt films and increased their microhardness without significant effect on current efficiency. Smoother and less defective coatings were also obtained from baths containing SDS and saccharin. The results revealed that both the current efficiency and microhardness were changed by variation of peak current density and duty cycle. Besides change of smooth morphology of the coatings to needle-shaped one, crystallite sizes and preferred orientation also varied with increasing the current density and duty cycle.

Optimization conditions for the electro-deposition of thin ZnTe film and effect of magnetic field

ZnTe is considered to be one of innovative semi-conducting materials because the theoretical energy band gap value is 2.26 eV suitable for solar cell or LED. And the further advantageous point is that the material of ZnTe is inexpensive and harmless. Among various synthesizing techniques, electro-deposition process has been investigated because the process is not expensive and suitable for mass production. In this study, optimum condition for producing the relatively thick film with strong magnetic field. The band gap value of thin ZnTe can be improved up to 2V in optimum conditions of electro-deposition and successive heat treatment. Furthermore, in order to achieve high performance of energy exchange, crystal orientation of ZnTe with cubic structure can be realized by electro-deposition of metal Te layer under strong magnetic field prior to ZnTe deposition.

Characteristics of electrodeposited bismuth telluride thin films with different crystal growth by adjusting electrolyte temperature and concentration

Bismuth telluride (Bi2Te3) thin films were prepared with various electrolyte temperatures (10°C–70 °C) and concentrations [Bi(NO3)3 and TeO2: 1.25–5.0 mM] in this study. The surface morphologies differed significantly between the experiments in which these two electrodeposition conditions were separately adjusted even though the applied current density was in the same range in both cases. At higher electrolyte temperatures, a dendrite crystal structure appeared on the film surface. However, the surface morphology did not change significantly as the electrolyte concentration increased. The dendrite crystal structure formation in the former case may have been caused by the diffusion lengths of the ions increasing with increasing electrolyte temperature. In such a state, the reactive points primarily occur at the tops of spiked areas, leading to dendrite crystal structure formation. In addition, the in-plane thermoelectric properties of Bi2Te3 thin films were measured at approximately 300 K. The power factor decreased drastically as the electrolyte temperature increased because of the decrease in electrical conductivity due to the dendrite crystal structure. However, the power factor did not strongly depend on the electrolyte concentration. The highest power factor [1.08 μW/(cm·K2)] was obtained at 3.75 mM. Therefore, to produce electrodeposited Bi2Te3 films with improved thermoelectric performances and relatively high deposition rates, the electrolyte temperature should be relatively low (30 °C) and the electrolyte concentration should be set at 3.75 mM.

A versatile electrochemical method to synthesize Co-CoO core-shell nanowires anodes for lithium ion batteries with superior stability and rate capability

A novel electrochemical method is proposed to synthesize nanostructured cobalt electrodes for lithium-ion batteries (LIBs). An array of cobalt nanowires (CoNWs) supported by a nanostructured copper current collector was obtained by the sequential electrodeposition of cobalt and copper into the nanopores of alumina templates and selective etching of alumina. The illustrated method can be implemented with one-side open alumina templates generated by one-step aluminium anodization, thus excluding the application alumina membranes and their coating by sputter metal deposition. The cobalt electrodeposition conditions allow to directly form Co-CoO core-shell nanowires, with metallic cobalt nanowires covered by a thin cobalt oxide film. The direct electrochemical growth of copper nanowires connected to CoNWs ensured high electronic conductivity and specific surface area of the resulting electrode, leading to a low interfacial impedance when used in lithium cell. This nanostructure and the enhanced lithium diffusion enabled by the nanowires morphology contributed to achieve a specific capacity of 1500 mAhg−1 after 200 cycles at 2 Ag-1, and complete restore of the capacity at 2 Ag-1 after cycling at the ultra-high current density of 450 Ag-1. The faradaic and capacitive contributions to charge storage were estimated by the analysis of cyclic voltammetry experiments carried out at different scan rates. Based on this latter analysis, pseudo-capacitive effects appear to play a pivotal role in determining the total recorded capacity. The advantages of the proposed method to sustain the large scale application of nanowires electrodes in lithium batteries are thoroughly discussed.

Effects of cathodic electrodeposition conditions on morphology and photoelectrochemical response of α-Fe2O3 photoanode

α-Fe2O3 photoanodes were prepared on Fluorine-doped tin oxide glass by annealing of electrodeposited Fe films. By controlling the synthesis parameters, the α-Fe2O3 film prepared from the Fe film electrodeposited in 0.05 M ferrous sulfate solution (pH = 2.1) for 50 s and then annealed at 600 °C for 3 h has the optimal photocurrent density around 257.08 μA cm−2 at 1.23 V vs. RHE (Reversible Hydrogen Electrode). In this paper, the effects of different synthesis parameters on α-Fe2O3 photoanodes were studied systematically. The morphology and properties of the sample were characterized with scanning electron microscopy, UV–vis spectra, X-ray diffractometry and photoelectrical measurements.

Additive Manufacturing through Galvanoforming of 3D Nickel Microarchitectures: Simulation‐Assisted Synthesis

AbstractElectrodeposition in combination with templates created by two‐photon lithography is used to fabricate dense metallic 3D microcomponents. Nanocrystalline nickel microcomponents deposited from nickel sulfamate electrolyte in 3D templates are presented. Using 3D electrodeposition simulation, different template designs for a bridge‐like microcomponent are investigated. The influence of the template design on current density is described. Electrodeposition conditions and pulse parameters are optimized with the simulation to achieve a high filling ratio within the template. Unlike previous work done in the field, the templates are made from negative tone photoresist, which is removed subsequent to the electrodeposition with plasma etching process. This allows for free‐form galvanoforming of freestanding nanocrystalline nickel microcomponents. Focused ion beam cross sections are made to investigate the microstructure within the specimen. The grains within the specimen show elongation along growth direction. Furthermore, the grain size distribution within the specimen shows correlation to the local current density values supplied by the simulation.