Galvanostatic Electrochemical Deposition Research Articles

Crystallographic and electrochemical corrosion resistance analyses of cataphoretically co-deposited spinel Co>0.5Mn0.1-0.3O0.1-0.4@rGO composites over α-Fe(110) as current collector for supercapatteries

Binder free spinel Co>0.5Mn0.1-0.3O0.1-0.4@rGO composite electrode films were fabricated via galvanostatic electrochemical deposition technique over α-Fe(110) as current collector for hybrid supercapattery. Self-designed, n-MOSFET embedded ATMega328P microcontroller assisted modules were deployed to record the chronopotentiometric as well as galvanostatic charging-discharging analysis for specific capacitance (Cs) measurements. Partial, exchange as well as limiting current densities(iL) and cathodic current efficiency were estimated. Electrochemical signature was analyzed from cyclic voltammetry data. Morphology and chemical nature of the composites were scrutinized with scanning electron microscopy, X-ray photoelectron, FT-IR and Raman spectra. Indigenously designed computer simulation programs coded in Python were used to optimize the deposition parameters and to analyze the crystalline structure from XRD data. The unit cell length for the FCC crystal with an octahedral geometry was ∼ 4.28 Å. An in-depth analysis of potentiodynamic polarization as well as electrochemical impedance spectral data were carried out to scrutinize the corrosion resistance and capacitance characteristics of the composites in KOH. From the Tafel constants, Ecorr, Icorr, Ru, RCT and ZW data, it was accentuated that rGO incorporated composite films offer enhanced corrosion protection for Fe(110) substrates than their individual counterparts along with augmented specific capacitance. Estimated Cs was about 1166 F.g−1 at a scan-rate of 10 mV.s−1. Impact of time-constant (τ) and current density over Cs was analyzed via GCD technique and was about 1458.73 F.g−1 at 2 τ and at 0.5 A.g−1. And the corresponding specific energy and power density were about 183.23 W.h.kg−1 and 237.75 W.kg−1 respectively. These composite electrode films impregnated with rGO not only improved the specific capacitance but also imparts the sacrificial corrosion resistance over the α-Fe(110) as current collector in presence of OH−as electrolyte and can serve as a sustainable electrode material for supercapatteries.

Cobalt recovery from spent lithium-ion batteries by leaching in H2SO4-N2 and H2SO4-O2 systems followed by electrochemical deposition

This paper is focused on cobalt valorization from the cathode material of spent lithium-ion batteries (LIBs) by using leaching and electrochemical deposition methods. During the leaching experiments, the degrees of cathode material dissolution in H2SO4-N2 and H2SO4-O2 systems were compared. Maximal degrees of cobalt extraction were 40 % in the former and 47 % in the latter system under following experimental conditions: H2SO4 concentration of 2 mol dm-3, nitrogen/oxygen volumetric flow of 2 L min-1, solid phase concentration of 33 g L-1, and temperature of 85?C. The rate of cobalt extraction from the cathode material in both investigated systems was the most favorable in the first 15 min, after which there was a sudden decrease in the reaction rate. Cobalt from the leaching solution was deposited on a copper substrate by galvanostatic electrochemical deposition with a current efficiency of 84%. The energy consumption was 5.8 kWh kg-1 of deposited Co. The cyclic voltammetry (CV) method was used to determine the potential of cobalt deposition, as well as side reactions taking place in the system. Scanning electron microscopy with energy dispersive spectrometry has shown that during the process of electrochemical deposition agglomeration of cobalt particles occurred (in the shape of cauliflower), while the metal was deposited in its elemental state, which was also confirmed by the results of X-ray diffraction analysis.

Electrochemically fabrication of a composite electrode based on tungsten oxide and cobalt on 3D Ni foam for high and stable electrochemical energy storage

The present work reports new findings on the electrical energy storage capabilities of WO3/Ni and Co@WO3/Ni electrodes produced via galvanostatic electrochemical deposition. The paper also describes a novel process for cleaning Ni foam, which has significant effect on the electrode's charge accumulation properties. Electrochemical measurements in an aqueous solution are performed to compare the supercapacitive behavior of the WO3/Ni foam and Co@WO3/Ni foam. The specific capacitance of the former electrode increases from 492.8 to 977.4 F g−1 because of Co adding into tungsten oxide. Furthermore, the former has 42.5% capacitance retention after 7000 charge-discharge cycles, while the latter has 83.7% owing to the Co loading. The specific energies are respectively calculated to be 64.27 Wh kg−1 and 64.44 Wh kg−1 for the pure WO3/Ni and Co@WO3/Ni electrodes. The specific powers are 3761.49 W kg−1 and 3303.90 W kg−1 for the former and latter electrodes. According to the findings, adding Co to the pure WO3/Ni electrode increases its electrochemical and supercapacitor capabilities, allowing it to be used in energy storage devices.

Effect of Doping Element and Electrolyte’s pH on the Properties of Hydroxyapatite Coatings Obtained by Pulsed Galvanostatic Technique

Hydroxyapatite (HAp) is the most widely used calcium phosphate as a coating on metal implants due to its biocompatibility and bioactivity. The aim of this research is to evaluate the effect of the pH’s electrolyte and doping element on the morphology, roughness, chemical, and phasic composition of hydroxyapatite-based coatings obtained by pulsed galvanostatic electrochemical deposition. As doping elements, both Sr and Ag were selected due to their good osseoinductive character and antibacterial effect, respectively. The electrolytes were prepared at pH 4 and 5, in which specific concentrations of Sr, Ag, and Sr + Ag were added. In terms of morphology, all coatings consist in ribbon-like crystals, which at pH 5 appear to be a little larger. Addition of Sr did not affect the morphology of HAp, while Ag addition has led to the formation of flower-like crystals agglomeration. When both doping elements were added, the flowers like agglomerations caused by the Ag have diminished, indicating the competition between Sr and Ag. X-Ray Diffraction analysis has highlighted that Sr and/or Ag have successfully substituted the Ca in the HAp structure. Moreover, at higher pH, the crystallinity of all HAp coatings was enhanced. Thus, it can be said that the electrolyte’s pH enhances to some extent the properties of HAp-based coatings, while the addition of Sr and/or Ag does not negatively impact the obtained features of HAp, indicating that by using pulsed galvanostatic electrochemical deposition, materials with tunable features dictated by the function of the coated medical device can be designed.

Superior galvanostatic electrochemical deposition of platinum nanograss provides high performance planar microelectrodes for in vitro neural recording

Objective. Platinum nanograss (Ptng) has been demonstrated as an excellent coating to increase the electrode roughness and reduce the impedance of microelectrodes for neural recording. However, the optimisation of the original potentiostatic electrochemical deposition (PSED) method has been performed by the original group only and no in vitro validation of functionality was reported. Approach. This study firstly reinvestigates the use of the PSED method for Ptng coating at different charge densities which highlights non-uniformities in the edges of the microelectrodes for increasing deposition charge densities, leading to a decreased impedance which is in fact an artefact. We then introduce a novel Ptng fabrication method of galvanostatic electrochemical deposition (GSED). Main results. We demonstrate that the GSED deposition method also significantly reduces the electrode impedance, raises the charge storage capacity and provides a significantly more planar electrode surface in comparison to the PSED method with negligible edge effects. In addition, we demonstrate how high-quality neural recordings were performed, for the first time, using the Ptng GSED deposition microelectrodes from human hNT neurons and how spiking and bursting were observed. Significance. Thus, the GSED Ptng deposition method presented here provides an alternative method of microelectrode fabrication for neural applications with excellent impedance and planarity of surface.

Galvanostatic electrochemical deposition of Cu-doped Mg(OH)2 thin films and fabrication of p-n homojunction

Conduction type control of transparent conducting materials is challenging. In this study, novel conductive p-type and n-type Cu-doped Mg(OH)2 thin films are obtained. The thin films are fabricated by both potentiostatic and galvanostatic electrochemical deposition with solutions containing 20 mM Mg(NO3)2 and different amounts (1–20 mM) of Cu(NO3)2. All specimens show high transmittance values more than 90 % in the visible range. The galvanostatically deposited films are n-type with 1 mM Cu in the solution while they are p-type with Cu amount of 3 mM or more. X-ray photoelectron spectroscopy results ascertain the presence of Cu+ and less amount of Cu2+ in the films. A p-n homojunction is fabricated by potentiostatic and galvanostatic deposition, and its current-voltage characteristic shows rectification properties.

Magnesium Doped Hydroxyapatite-Based Coatings Obtained by Pulsed Galvanostatic Electrochemical Deposition with Adjustable Electrochemical Behavior

The aim of this study was to adapt the electrochemical behavior in synthetic body fluid (SBF) of hydroxyapatite-based coatings obtained by pulsed galvanostatic electrochemical deposition through addition of Mg in different concentrations. The coatings were obtained by electrochemical deposition in a typical three electrodes electrochemical cell in galvanic pulsed mode. The electrolyte was obtained by subsequently dissolving Ca(NO3)2·4H2O, NH4H2PO4, and Mg(NO3)2·6H2O in ultra-pure water and the pH value was set to 5. The morphology consists of elongated and thin ribbon-like crystals for hydroxyapatite (HAp), which after the addition of Mg became a little wider. The elemental and phase composition evidenced that HAp was successfully doped with Mg through pulsed galvanostatic electrochemical deposition. The characteristics and properties of hydroxyapatite obtained electrochemically can be controlled by adding Mg in different concentrations, thus being able to obtain materials with different properties and characteristics. In addition, the addition of Mg can lead to the control of hydroxyapatite bioactive ceramics in terms of dissolution rate.

Fabrication of Long-Range Ordered Aluminum Oxide and Fe/Au Multilayered Nanowires for 3-D Magnetic Memory

Large-scale long-range ordered anodic aluminum oxide and multilayered nanowires (NWs) are attractive to 3-D nanostructured material applications, such as high-density 3-D magnetic memory. This article demonstrates long-range ordered aluminum oxide made by simple and inexpensive double imprinting with line-patterned stamp and uniform iron-gold multilayered NWs fabricated by galvanostatic electrochemical deposition with a single electrolyte bath. These two structural features show potential for future high-density recording systems that require long-range ordered devices separated from each other by insulation to eliminate crosstalk.

Fabrication of photovoltaic FeSxOy/ZnO heterostructures by electrochemical deposition

FeSxOy/ZnO heterostructures are fabricated by the electrochemical deposition (ECD) method. ZnO is first deposited by galvanostatic ECD on indium-tin-oxide (ITO) substrate and then FeSxOy is deposited on ZnO. In ECD of FeSxOy, three-step pulse bias is adopted in addition to DC bias. The addition of a complexing agent (tartaric acid) and stirring of the solution is also examined. With tartaric acid in the solution, FeSxOy deposition on ZnO failed. Without tartaric acid, FeSxOy/ZnO heterojunctions showing rectifying electrical properties are fabricated. Weak photovoltaic effects are confirmed only when FeSxOy is deposited by three-step pulse with stirring.

Morphological variation of electrodeposited nanostructured Ni-Co alloy electrodes and their property for hydrogen evolution reaction

Nanostructured nickel-cobalt alloys of the content of Co varying from 0% to 75% for hydrogen evolution reaction were fabricated by galvanostatic electrochemical deposition processes. With the incorporation of Co into Ni matrix, the morphologies of Ni-Co alloys are changed from nanocones to lamellar structure and finally evolved to a mixed shape of nanocone structure and lamellar structure. Among these Ni-Co alloys, the optimal Ni-60%Co alloy exhibits outstanding electrocatalytic activity with a small hydrogen overpotential of −180 mV and follows Volmer-Tafel mechanism. Better performance of Ni-60%Co can be attributed to the synergetic combination of Ni and Co and unique complex mesh structure which provides the enlarged exposure of catalytically active sites. In addition, Ni-60%Co alloy also displays good electrochemical stability under 10 h galvanostatic test. With prominent electrochemical properties, Ni-60%Co alloy has a certain advantage in the catalytic hydrogen evolution material.

Subjective somatic symptoms among victims of offensive behaviors at the workplace

Nanostructured nickel-cobalt alloys of the content of Co varying from 0% to 75% for hydrogen evolution reaction were fabricated by galvanostatic electrochemical deposition processes. With the incorporation of Co into Ni matrix, the morphologies of Ni-Co alloys are changed from nanocones to lamellar structure and finally evolved to a mixed shape of nanocone structure and lamellar structure. Among these Ni-Co alloys, the optimal Ni-60%Co alloy exhibits outstanding electrocatalytic activity with a small hydrogen overpotential of −180 mV and follows Volmer-Tafel mechanism. Better performance of Ni-60%Co can be attributed to the synergetic combination of Ni and Co and unique complex mesh structure which provides the enlarged exposure of catalytically active sites. In addition, Ni-60%Co alloy also displays good electrochemical stability under 10 h galvanostatic test. With prominent electrochemical properties, Ni-60%Co alloy has a certain advantage in the catalytic hydrogen evolution material.

Fast electrochemical deposition of Ni(OH)2 precursor involving water electrolysis for fabrication of NiO thin films

Ni(OH)2 precursor films were deposited by galvanostatic electrochemical deposition (ECD), and NiO thin films were fabricated by annealing in air. The effects of the deposition current densities were studied in a range that included current densities high enough to electrolyze water and generate hydrogen bubbles. The films fabricated by ECD involving water electrolysis had higher transparency and smoother surface morphology than those deposited with lower current densities. In addition, the annealed NiO films clearly had preferred (111) orientation when the deposition was accompanied by water electrolysis. p-type conduction was confirmed for the annealed films.

CuNi Alloy Electrodeposition for Microbumps Using Benzotriazole

A pressing issue in flip-chip and stacked integrated circuit (SIC) technology is the breakdown of microbumps over time. These microbumps are the physical and electrical connections between the chips. They consist out of Cu stages on both chips which are typically soldered together by Sn. Due to diffusion and electromigration, Cu and Sn form two intermetallic phases of which Cu3Sn induces microvoids at the Cu3Sn/Cu interface causing in turn breakdown of the microbump. Chemical modelling shows that a CuNi alloy, with an approximate 9:1 Cu:Ni ratio, together with Sn doesn’t form the Cu3Sn intermetallic compound thus tremendously improving the stability of the microbumps, and therefore the chip. By far the most feasible method to manufacture microbumps is galvanostatic electrochemical deposition. However, electrochemical CuNi co-deposition from a single deposition bath requires current densities higher than the limiting current density of copper causing rough, uncontrolled dendritical growth of Cu. Existing CuNi baths are citrate based but citrates can corrupt other features of the chip manufacturing process. In this work the possibility of smooth, solid solution electrodeposition of CuNi in a 9:1 ratio using benzotriazole (BTA) is investigated. Benzotriazole is a well-known corrosion inhibitor for copper. Here we show that BTA has a tremendous potential for suppressing Cu2+ reduction and limiting the uncontrolled mass-transfer limited Cu growth. First we demonstrate with a RDE voltammetric investigation, together with viscosimetry, the effects of the combination of an existing CuSO4 and a NiSO4 bath on Cu2+ reduction. Then, we introduce BTA and show the large difference between the working of BTA in the combined bath and in a CuSO4 only bath. Later, we improve the working of BTA by increasing the pH thus defining a parameter window for which we’re able to deposit CuNi with a maximum suppressing effect of BTA. CuNi deposits on metal pellets with a Cu substrate layer are investigated by SEM and EDX to evaluate the morphology and elemental composition of the deposit. We were able to demonstrate the change in CuNi morphology upon increasing the BTA concentration from 0 to 1000 ppm. No distinction could be made in Cu or Ni rich areas over different deposit areas indicating that we’re able to deposit CuNi as a solid solution. Figure 1

Pd and polyaniline nanocomposite on carbon fiber paper as an efficient direct formic acid fuel cell anode

Direct formic acid fuel cells are advantageous as portable power generating devices. In the present work, an anode catalyst for direct formic acid fuel cell (DFAFC) is presented which has good catalytic activity for formic acid oxidation. The catalyst is composed of Pd and conducting polymer polyaniline (Pd-PANI) nanocomposite. The catalyst was prepared by using a single step galvanostatic electrochemical deposition method. The Pd-PANI catalyst was electrodeposited at different time durations and a comparison of the catalytic activity at each deposition time was carried out and optimized.

Effects of complexing agents on electrochemical deposition of FeSxOy in ZnO/FeSxOy heterostructures

Heterostructures which consist of ZnO and FeSxOy were deposited via electrochemical deposition (ECD) for application to solar cells. Galvanostatic ECD was used in FeSxOy deposition with a solution containing 100 mM Na2S2O3 and 30 mM FeSO4. To alter the film properties, L(+)-tartaric acid (C4H6O6) and lactic acid [CH3CH(OH)COOH] were introduced as the complexing agents into the FeSxOy deposition solution. Larger film thickness and smaller oxygen content were obtained for the films deposited with the complexing agents. ZnO was deposited on FeSxOy by two-step pulse ECD from a solution containing Zn(NO3)2. For the ZnO/FeSxOy heterostructures fabricated with/without complexing agents, rectifying properties were confirmed in the current density–voltage (J–V) characteristics. However, photovoltaic properties were not improved with addition of both complexing agents.

Effects of complexing agents on electrochemical deposition of FeSxOy thin films

FeSxOy thin films were deposited on indium–tin-oxide (ITO)-coated glass substrates at 15 °C via galvanostatic electrochemical deposition from an aqueous solution containing 100 mM Na2S2O3 and 30 mM FeSO4. The effects of l(+)-tartaric acid (C4H4O6) and lactic acid [CH3CH(OH)COOH] at different concentrations were investigated. All the deposited films were amorphous. With the complexing agents, the thickness was increased, and the oxygen content was reduced significantly compared with the sample deposited without the complexing agents. In the photoelectrochemical measurement, p-type conductivity was confirmed. The photoresponsivity was not influenced significantly by the complexing agent, suggesting that the oxygen content does not drastically affect the properties of the deposited films probably because the local bonding configuration around Fe atoms in FeSxOy is similar to that in FeS2.

Electrodeposited nanostructured cobalt film and its dual modulation of both superhydrophobic property and adhesiveness

We report a novel shell-like cobalt nanostructure prepared by galvanostatic electrochemical deposition which exhibit prominent superhydrophobic property. By adjusting the electroplating conditions, cobalt nanocrystals with different morphologies like nanocones and fluffy shells can be obtained while the hydrophobic and adhesive behavior of each after surface modification is observed. After a brief discussion on the growth mechanism of those shapes, we explained the lotus effect presented on such structures which would probably provide a strong evidence to the existing models of superhydrophobic surfaces. Based on the above, we propose a novel approach to modulate both adhesiveness and wettability of Co film by tuning of deposition parameters along with a simple heat treatment and dipping. With cobalt's anisotropic magnetic properties, such facile surface coating would be used in a wide range of applications such as commercial fabrication of tunable anti-corrosive magnetic devices.

Synthesis of hierarchical mushroom-like cobalt nanostructures based on one-step galvanostatic electrochemical deposition

Hierarchical mushroom-like cobalt materials were synthesized by galvanostatic electroplating. The morphology of the product, which can evolve from cone-like to mushroom-like nanostructures, is controllable by changing the deposition parameters. The nanostructure is a single hexagonal close-packed crystal with a preferential growth direction. The proposed growth mechanism is based on the metal ion deficient layer (MIDL) theory which explains both the time-dependent morphology evolution and the effects of the crystalline modifier C2H4(NH2)2. Depositions using several organic crystalline modifiers were compared; only C2H4(NH2)2 yielded the mushroom-like structure.

Electrochemical Deposition of Platinum Interconnects on Flexible Biocompatible Substrates

ABSTRACTWe explored the use of galvanostatic electrochemical deposition of Pt for cost-effective fabrication of interconnects in flexible implantable bio-medical devices. Initial studies were done on coupons diced from 200 mm Si wafers coated with PVD TiN. Based on the physical and chemical properties of the electrodeposited Pt films, optimal conditions were chosen for through-mask plating of centimeters long Pt lines on flexible, medical grade, releasable polyimide layers. Possibility for further up-scaling was considered with special emphasis on high throughput manufacturing of Pt interconnects with good adhesion to TiN/flexible substrates, low impurity content and resistivity, and acceptable roughness and uniformity.

Effects of electrolyte on ZnO nanostructures synthesized by galvanostatic electrochemical deposition and their UV sensing properties

In this study, ZnO nanorods (NRs) and nanocombs (NCs) are synthesized by simple galvanostatic electrochemical deposition technique, without prepared any ZnO seed-layer or catalyst. The effect of the different morphologies on the UV sensing characteristics has been studied under ambient conditions. The photoluminescence (PL) spectra and time-dependent photoresponse of the ZnO nanostructures exhibited good optical properties. At room temperature, NCs showed superior response with 9% change of its resistance, few seconds response time and fully recovery. Inversely, in high temperature ZnO NRs indicated better response than NCs with the variation of 25% of its resistance. The dependence photoresponse on temperature demonstrated clearly how surface-defects affect on UV response of ZnO nanostructures. Our approach is to provide a simple and cost-effective way to fabricate UV detectors.