Electrodeposition Potentials Research Articles

Optimizing preparation conditions and characterizing for CoxPt1-x alloy cylindrical nanowires fabricated by electrodeposition on nanoporous polycarbonate membranes

This study investigated the influence of the preparation conditions on the Co composition, crystal structure, and magnetic and electric conduction properties of cylindrical CoxPt1-x alloy nanowires having 0.08 ≤ x ≤ 0.90, which were electrodeposited on nanoporous templates. When prepared with an optimal concentration ratio of Co and Pt aqueous solutions and electrodeposition potentials, highly oriented crystal structures of fcc Co-Pt (111) was obtained in CoxPt1-x nanowires (0.58 ≤ x ≤ 0.80). Nanowires with (111)-oriented fcc Co-Pt crystals exhibited average lengths and diameters of 5.8–10.8 μm and 130 nm, respectively, and showed an easy axis of magnetocrystalline anisotropy in the longitudinal direction of the nanowire. These results indicate a direct correlation between the crystal structure and magnetic properties. The concentration ratio of Co and Pt in the electrolytes and the electrodeposition potentials for fabricating CoxPt1-x alloy nanowires using the diluted Co composition (0.08 ≤ x ≤ 0.25) were determined. These nanowires were polycrystalline and had a small saturation magnetization. Furthermore, the anisotropic magnetoresistance (AMR) for a single CoxPt1-x nanowire was measured to estimate the domain wall (DW) width in the single CoxPt1-x nanowire. The value of the magnetoresistance (MR) ratio for the single nanowire (0.58 ≤ x ≤ 0.80) with highly (111)-oriented fcc Co-Pt crystal was 0.082–0.23 %, and the estimated value of DW width was 17–25 nm. These findings provide valuable information for constructing three-dimensional magnetic memory devices.

Electrodeposition Behavior of Al-Au Alloys in AlCl3-NaCl-KCl-Aucl Molten Salt

Quartz Crystal Microbalance (QCM) has been used as a highly sensitive mass sensor. This study aims to form porous gold thin films on QCM elements and apply them to highly sensitive gas sensors by attaching selective media. Physical vapor deposition and chemical etching are known methods for forming porous Au thin films. In this study, the electrochemical formation of porous gold films in AlCl3-NaCl-KCl molten salts containing AuCl was investigated. There are few reports about electrodeposition and dissolution potentials of Au in the molten salt electrolyte. As a first step in this study, voltammogram measurements and constant potential electrolysis were performed in the electrolyte, and electrodeposition potentials of Au and Al-Au alloys were discussed.An electrolyte in this study is a mixture of 61 mol% AlCl3- 26 mol% NaCl- 13 mol% KCl molten salt. The mixture salt was melted at 443 K and AuCl was added to the molten salt. A glassy carbon plate (GC) and a pure Al wire were used as the working electrode and reference electrode, respectively. The GC plate and Au mesh were used as the counter electrode for voltammogram measurement and constant potential electrolysis, respectively. Voltammogram measurements were carried out at potential range from -0.1 to 2.4 V vs. Al/Al(Ⅲ). Constant potential electrolysis was performed in the range from -0.2 to 0.3 V with an electric charge density of 40 C cm-2. The electrodeposits were observed by scanning electron microscopy (SEM) and determined the composition of Al and Au by energy dispersive X-ray spectroscopy (EDS).Au ions concentration in the electrolyte was 2.5 mmol dm-3. In voltammogram measurements, a small cathodic current was observed at about 0.8 V, then gradually increased from 0.2 V. In the potential lower than 0 V, a drastical increase of cathodic current was observed, which was attributed to Al electrodeposition. When the potential was reversed, large anodic current flowed from 0 V and a small current peak was also observed at 0.2 V. These were considered to correspond to the dissolution of Al and Al-Au alloys, respectively. Furthermore, a relatively large anodic current peak was observed at about 2 V, which was expected to be due to the dissolution of Au. From the results of constant potential electrolysis, the Au concentration in the electrodeposits at -0.1 V and -0.2 V was less than 1 at%. At 0 V, the Au concentration in the electrodeposit increased sharply to 84 at%, and at 0.3 V it increased moderately to 89 at%. From SEM observation, the morphology of the electrodeposits at -0.1 V and -0.2 V was dense, while that at potentials more than 0 V was sponge-like.AcknowledgementsThis work was supported by JST SICORP and JPMJSC2108.

Evaluating the Effects of Surfactant Templates on the Electrocatalytic Activity and Durability of Multifaceted Platinum Nanostructures

High-surface-area multifaceted platinum (Pt) nanoparticles (NPs) exhibit promising electrocatalytic properties for various electrochemical reactions. Effective structural and morphological control is a key factor in attaining improved electrocatalytic activities. Herein, we use low concentrations of surfactants (≲ critical micelle concentration) as templates during Pt electrodeposition to produce multifaceted Pt NPs and evaluate their electrochemical active surface area (Aecsa) and activity for the oxygen reduction reaction (ORR). The electrodeposition potentials for the nucleation and growth stages were optimized through an evaluation of the surface coverage and uniformity of the size of the electrodeposited particles. The electrodeposition was performed in the presence of a cationic (i.e., cetyltrimethylammonium bromide, CTAB), anionic (i.e., sodium dodecyl sulfate, SDS), or non-ionic [i.e., polyoxyethylene (20) stearyl ether, Brij 78] surfactant. The deposited Pt NPs have the mean diameter of 49 ± 11 nm for Brij 78, 54 ± 9 nm for CTAB, and 57 ± 14 nm for SDS, with faceted crystallites exposed on their surfaces as observed using high-resolution transmission electron microscopy. The Aecsa of these Pt nanostructures increased when using surfactants as templates during electrodeposition; the Aecsa increased in the order of non-templated Pt (12.4 m2 g–1) < Pt-CTAB (16.2 m2 g–1) < Pt-SDS (17.1 m2 g–1) < Pt-Brij 78 (20.4 m2 g–1). The mass activities of Pt-CTAB, Pt-SDS, and Pt-Brij 78 toward the ORR were also calculated to be, respectively, ∼1.5, 1.6, and 2.0 times higher than that of non-templated Pt at 0.8 V (vs RHE). The Pt NPs electrodeposited in the presence of surfactants exhibited structural durability when subjected to a test of 5000 cycles of the applied potential in a square wave form between 0.6 and 0.95 V (vs RHE). This comparative study offers several insights into the design of surfactant-assisted electrodeposition techniques for creating multifaceted Pt with enhanced surface area and activity toward the ORR and electrocatalytic stability.

Evaluation of Pd-Co Bimetallic Electrocatalysts in the Formic Acid Oxidation Reaction

The main focus of this research is the synthesis and evaluation of Pd-Co bimetallic catalysts, in the formic acid electrochemical oxidation reaction (FAOR). The catalysts used were synthesized by electrodeposition using a choline chloride and urea Deep Eutectic Solvent (DES) termed reline, as electrolytic medium. Electrodeposition potentials were previously selected after analysis by Cyclic Voltammetry (CV) and used in Chronoamperometry (CA). The electrode modified with bimetallic nanoparticles (NPs) was used for FAOR, which is a key reaction in direct formic acid fuel cells (DFAFCs). Electrodeposits were characterized by Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX) to determine diameters, morphology and analysis of elements that make up the bimetallic NPs.

Controlling Micro-Architecture in Dendritic Cu-Ni Heterostructures for Energy Storage and Conversion Applications

A simple and innovative technique was developed in this work creating a stable, fully established porous three dimensional (3D) dendritic structure, which can be adopted as electrode for redox supercapacitors and catalytic energy conversion reactions 1,2. By controlling the surfactant and etching chemistry a series of different micro-architectured morphologies was created for Cu-Ni heterostructures (Fig. 1a) during their dendritic growth at suitable electrodeposition potentials. This work examines in detail the effect of the deposition conditions on the mass and chemical composition (Fig. 1b), and morphology (Fig. 1c-d), mass and chemical composition (Fig. 1e) of the deposited Ni/Cu electrodes and the resulting 3D architectures of the dendritic growth. The porosity, architecture, geometric confinement, and the exposed crystallographic facets were found to play crucial roles in the energy storage and catalytic outcomes yielding insightful structure-activity correlations3. Cyclic Voltammetry (CV) studies reveal clear pseudocapacitive nature of the electrodes with the 10 minutes deposited Ni/Cu redox electrode exhibiting very high specific capacitance of 643 F.g−1 at 1 A.g−1 (Fig. 1e-f). The fabricated electrode delivers the capacitance retention of 84% after 5000 consecutive charge discharge cycles (Fig. 1g). These results spotlight the mechanism involved in the electrodeposition and the influence of the observed mass and deposition duration that modifies the electrode content and morphology, as well as its electrochemical activity. Furthermore, the microtraps present in the architectural matrix and the relative composition of Cu to Ni was fine tuned to efficiently direct the reaction pathway towards C2 products during CO2 electroreduction (eCO2R)4. The local confinement of the suitable intermediates and production of CO and H* in proximal sites leads to controlled product tunability towards higher carbon containing hydrogenated products with high faradaic efficiency5. The structure-activity correlations developed here through operando and postmortem analyses corroborated by computational studies, will help guide future material design strategies for enhanced energy storage and catalytic applications. Keywords: electrodeposition, CuNi structures, microtraps, pseudocapacitor, CO2 reductionFig. 1. a) XRD pattern and b) XPS spectrum of Cu-Ni heterostructure, c) and d) SEM micrographs of the micro-architectured morphologies obtained by controlling the surfactant and etching chemistry, e) and f) CV studies of 10 min deposited Ni/Cu redox electrode, and g) Charge-discharge cycles of the fabricated electrode. References Zou, R. et al. Dendritic Heterojunction Nanowire Arrays for High-Performance Supercapacitors. Sci. Reports 2015 51 5, 1–7 (2015).Zang, D., Huang, Y., Li, Q., Tang, Y. & Wei, Y. Cu dendrites induced by the Anderson-type polyoxometalate NiMo6O24 as a promising electrocatalyst for enhanced hydrogen evolution. Appl. Catal. B Environ. 249, 163–171 (2019).Sebastiá n-Pascual, P., Jordã Pereira, I. & Escudero-Escribano, M. Tailored electrocatalysts by controlled electrochemical deposition and surface nanostructuring. Chem. Commun 56, 13261 (2020).Zhuang, T. T. et al. Copper nanocavities confine intermediates for efficient electrosynthesis of C3 alcohol fuels from carbon monoxide. Nat. Catal. 1, (2018).Sebastián‐Pascual, P., Mezzavilla, S., Stephens, I. E. L. & Escudero‐Escribano, M. Structure‐Sensitivity and Electrolyte Effects in CO 2 Electroreduction: From Model Studies to Applications. ChemCatChem 11, 3626–3645 (2019). Figure 1

Electrodeposition of Ni–Fe alloy from solutions based on deep eutectic solvent ethaline

The kinetics of сodeposition of nickel and iron in an electrolyte based on a deep eutectic solvent (ethaline) was studied by voltammetry method. It was established that the partial voltammograms of iron ions reduction during alloy electrodeposition correspond to the region of electrode potentials, which is more than 100 mV positive in comparison with the electrodeposition potentials of pure iron. It was shown that the acceleration of iron ion electroreduction is associated with the gain in energy due to the alloy formation and a decrease in the overvoltage of iron electrodeposition during alloying. The change in the kinetics of iron electrodeposition can be explained by both a change in the mechanism of its electrodeposition in conjunction with nickel and a change in the state of the electrode surface in the potential region of the alloy formation. Comparison between the ratio of the content of the alloy components in the metal and the corresponding ions in the electrolyte showed that nickel and iron electrodeposit into the alloy in quantities that are proportional to their content in the electrolyte. Thus, electrodeposition of nickel-iron alloy from ethaline with a water content of up to 3% occurs by the so-called normal mechanism.

Composition and structure of Ti–Al alloy powders formed by electrochemical co-deposition in KCl–LiCl–MgCl2–TiCl3–AlCl3 molten salt

Direct electrochemical deposition from titanium and aluminum chlorides is a green and short process for preparing Ti–Al alloy powders, thereby relevant for replacing the conventional smelting process characterized by intermittent and high production costs. However, the morphologies and compositions of resulting Ti–Al alloy powders have not yet been systematically studied. Here, Ti–Al alloy powders with different compositions and morphologies were successfully prepared from a molten KCl–LiCl–MgCl2 salt containing AlCl3 and TiCl3 under different electrodeposition parameters. The electrochemical behaviors of Ti and Al ions were examined on Mo and Al working electrodes by cyclic voltammetry at different temperatures. The results revealed variable numbers of redox peaks with temperature and working electrode material. The influences of the cathodic parameters on compositions and morphologies of Ti–Al alloy products studied through potentiostatic and galvanostatic electrolysis revealed that factors like cathodic potentials, initial current densities, and mole ratios of TiCl3/AlCl3 greatly influenced the chemical compositions of Ti–Al alloy products except for temperatures. Also, phase compositions of Ti–Al alloy products were mainly controlled by the electrodeposition potentials and mole ratios of TiCl3/AlCl3. Meanwhile, the morphologies and particle sizes of Ti–Al alloy powders varied with temperature, current density, and electrolyte composition. In sum, these findings look promising for future formation of Ti–Al alloy powders for various uses.

Potential dependent Ag nanoparticle electrodeposition on Vulcan XC-72R carbon support for alkaline oxygen reduction reaction

Abstract Carbon-supported Ag nanocatalysts, synthesized at five different electrodeposition potentials ranging from 0.0 to 0.4 V vs. RHE, were successfully prepared by using the rotating disk slurry electrode (RoDSE) technique. This was done to determine the ideal electrodeposition parameters that facilitate optimal metal loading and particle dispersion for an efficient oxygen reduction reaction (ORR) through the 4-e- pathway. In this study, the potentials were chosen based on different regions of Ag electrodeposition on a clean glassy carbon electrode. Each Ag/Vulcan catalyst was characterized using different techniques including TEM, XRD, ICP-OES, XPS, and Raman spectroscopy. These techniques confirmed the presence of Ag on the carbon support and determined that the applied potential affected the Ag oxidation state and catalytic ORR activity. Herein, we show that as the electrodeposition potential increases, we observe a lower electrodeposition current. This suggests gentle Ag deposition on the carbon support, resulting in reduced agglomeration. We confirm that the deposition potential of the Ag has a direct effect on the electrocatalytic behavior of the Ag/C catalyst. Ag crystallinity was determined using XRD, which showed a particle size in the range of 1 to 35 nm for each potential. ORR studies were conducted in O2 saturated 0.1 M KOH solution using the rotating disk electrode (RDE) technique and cyclic voltammetry. The oxygen species at the Ag NPs surface suggest a synergistic effect in the ORR mechanism. Finally, among the five studied electrodeposition potentials of Ag, 0.1 V vs. RHE provided the optimal conditions to generate Ag catalysts with low agglomeration, small particle size, high ORR mass activity, and electron transfer equal to 3.5 in 0.1 M KOH electrolyte.

Recovery of Silver and Gold From Electronic Waste by Electrodeposition in Ethaline Ionic Liquid

The recycling of metals from electronic equipment waste (e-waste) is of great concern today. The work described in the article focuses on the application of ionic liquids (ILs) to selectively recover of precious metals (Ag and Au) from the anodic slime obtained at the anodic dissolution of cast e-waste. The ingots obtained from molten and cast anodic slime were selectively dissolved in ILs. Silver and gold compositions of the ingots: 39.7 wt.% and respectively 18.9 wt.%. The IL used was an eutectic mixture of choline chloride with ethylene glycol in a 1:2 molar ratio. As catalytic/oxidizing agent, there was used pure iodine in a concentration of 0.1-0.2 moldm-3 at 298-303 K. Cyclic voltammetry was employed for the determination of the electrochemical windows of ILs as well as of the dissolution and electrodeposition potentials of principal metals present in the ingot (anode). For Ag and Au, the deposition potentials determined were 0.074 V and respectively 0.696 V. The XRD and SEM-EDX analyses revealed that the content of precious metals in the cathodic deposits was 99 wt.% for Ag and respectively ]70 wt.% for Au. We demonstrated that ILs electrolytes could be a solution to selective recovery of precious metals from e-waste.

Light-Irradiated Electrochemical Direct Construction of Cu2O/CuO Bilayers by Switching Cathodic/Anodic Polarization in Copper(II)-Tartrate Complex Aqueous Solution.

p-CuO with a band gap energy of 1.5 eV, p-Cu2O with a band gap energy of 2.05 eV, and their bilayers were prepared by controlling the potential of anodic and cathodic polarization in a copper(II)–tartrate complex aqueous solution containing copper(II) sulfate hydrate and tartaric acid in the dark and under light irradiation. Electrochemical characteristics of the electrodeposition and the resultant CuO and Cu2O layers were investigated with cyclic voltammetry, chronoamperometry, and Mott–Schottky plots, and the structural and optical characterizations were performed with X-ray diffraction, scanning electron microscopy, and optical absorption spectra measurements. The CuO layer prepared at 0.4–0.7 V was composed of aggregates of granular grains with the monoclinic lattice, and the Cu2O layer composed of coarse grains with the cubic lattice was deposited at −0.4 to 0.6 V. The flat-band potentials were estimated to be 0.145 and −0.1 V (vs Ag/AgCl) for the CuO and Cu2O layers, respectively. The 0.4 μm CuO/1.1 μm Cu2O bilayers could be prepared by switching the electrodeposition potentials of 0.4 and −0.4 V, irrespective of the presence of light irradiation. The photoelectrodeposition under light irradiation enabled the preparation of continuous and dense 1.1 μm Cu2O/0.4 μm CuO bilayer by controlling the potential, while electrodeposition in the dark led to sparse, isolated, and coarse Cu2O grains being deposited. The mechanism for the photoelectrodeposition of the bilayers was discussed based on the energy band alignment at the heterointerface to the Cu–tartrate complex solution.

Effect of Photoelectrochemical Electrolyte Additives on the Photoconversion Efficiency of Tungsten Trioxide Loaded Titania Nanotubes Prepared Via Electrodeposition

This study aims to investigate the effect of additives (sulfuric acid and ethanol) in sodium sulfate as photoelectrochemical (PEC) electrolyte on the photoconversion efficiency of tungsten trioxide loaded titania nanotubes (WTNT). Titania nanotubes (TNT) were first fabricated via anodization while the deposition of tungsten trioxide onto the titania nanotubes (WTNT) were successfully carried out via electrodeposition at various potentials. Assessing the PEC performance of WTNT fabricated at pH 1.5 in solely sodium sulfate was not adequate to enhance the PEC performance of WTNT compared to blank TNT. A similar result was obtained when sulfuric acid was added or when fabricating WTNT at pH 0.8. Adding ethanol into sodium sulfate electrolyte has successfully improved the PEC performance of WTNT with observable inclining photoconversion efficiency trend upon increasing electrodeposition potentials of WTNT from −0.45 V to −0.75 V.

Preparation and characterization of electrodeposited Ni-Ru alloys: morphological and catalytic study

Nickel-ruthenium alloys with various compositions have been deposited by electrodeposition for the first time. Cyclic voltammetry and linear stripping voltammetry measurements show that codeposition of nickel with ruthenium is possible below the potential value of nickel reduction. High-quality alloys containing nickel and ruthenium can be plated at cathodic potentials ranging from − 0.5 to − 1.0 V vs SCE. Deposited coatings were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The diffractograms obtained show that an increase of nickel concentration in alloy will lead to a change in the phase composition and formation of NiRu (100) and (101) phases which is observed to be 78 mas.% Ni. SEM studies confirm the surface homogeneity and presence of small, regular grains. AFM observation allows the estimation of the real surface area of obtained alloys which increase with more negative electrodeposition potentials. Ni-Ru alloys were found to be highly electroactive in the water splitting process, which can be connected with the presence of the NiRu phase and a well-developed electroactive area.Graphical Electrochemical deposition of Ni-Ru alloys with various composition and their catalytic activity in water splitting process

Microbial Corrosion Resistance and Antibacterial Property of Electrodeposited Zn-Ni-Chitosan Coatings.

Microbial corrosion is a universal phenomenon in salt water media such as seawater and wastewater environments. As a kind of efficient protective metal coating for steel, the damage of the Zn–Ni alloy coating was found to be accelerated under microbial corrosive conditions. To solve this problem, chitosan, which is considered a natural product with high antibacterial efficiency, was added to Zn–Ni electrolytes as a functional ingredient of electrodeposited Zn–Ni–chitosan coatings. It was found that the addition of chitosan significantly and negatively shifted the electrodeposition potentials and influenced the Ni contents, the phase composition, and the surface morphologies. By exposing the coatings in a sulfate-reducing bacteria medium, the microbial corrosion resistance was investigated. The results showed that compared to the Zn–Ni alloy coating, Zn–Ni–chitosan coatings showed obvious inhibiting effects on sulfate-reducing bacteria (SRB) and the corrosion rates of these coatings were mitigated to some degree. Further research on the coatings immersed in an Escherichia coli-suspended phosphate buffer saline medium showed that the bacteria attachment on the coating surface was effectively reduced, which indicated enhanced antibacterial properties. As a result, the Zn–Ni–chitosan coatings showed remarkably enhanced anticorrosive and antibacterial properties.

Electrochemical behaviors and electrodeposition of single-phase Cu-Sn alloy coating in [BMIM]Cl

In this work, copper-tin (Cu-Sn) alloy coating was prepared in 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) using electrodeposition method. The electrochemical behaviors of different electrolytes and the electrodeposition reversibility of Cu-Sn alloy were studied using cyclic voltammetry (CV). The electro-crystallization mechanism was investigated using chronoamperometry at different step potentials on glassy carbon (GC) electrode. The micromorphology and phase composition of Cu-Sn alloy coatings were characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results showed a new reduction peak located at −0.50 ∼ −1.00 V, which belonged to Cu-Sn co-deposition. The reduction of Cu-Sn alloy in this system was an irreversible process. The electro-crystallization of Cu-Sn alloy followed the three-dimensional instantaneous nucleation. The results for micro-morphologies showed that, when the potential is changed, different microstructures can be formed, whereas the morphology changed from snow-like to cypress leaf-like shape. The results for phase composition showed that Cu-Sn alloy coating at different electrodeposition potentials consisted of pure cubic system Cu13.7Sn phase. Additionally, the Cu-Sn alloy deposition from [BMIM]Cl system showed a preferred orientation on (220) crystallographic plane, which is different from the standard card.

Horseradish Peroxidase Immobilized on Polyaniline onto Monocrystalline Silicon for Glyphosate Herbicide Detection

In this work a special electrode configuration with potential application in enzymatic biosensors for the detection of glyphosate was studied. The enzyme used was Horseradish Peroxidase (HRP), which was immobilized on a polyaniline film (PAni), electrodeposited on the surface of the n-type monocrystalline silicon electrode. PAni has the ability to bind to biomolecules and thereby potentiate their biocatalytic properties by favoring the transfer of electrons between enzyme and substrate. Monocrystalline silicon is one of the most used materials in electronic technology due to its semiconductor character. In this work, different parameters were investigated in the electrode preparation, including concentration of polyaniline in the electrodeposition solutions, as well as the electrodeposition times and potentials. The response of the electrode as biosensor was evaluated by the electric current density characteristic of hydroquinone oxidation in the presence of standardized glyphosate solutions. The peroxidase enzyme catalyzes the oxidation of hydroquinone to the o-quinone form in the presence of hydrogen peroxide. In turn, glyphosate inhibits the activity of HRP and causes a reduction of the electric current density in the biosensor electrode. The results obtained with glyphosate using the proposed method are in agreement with the literature and show that the n-Si/PAni/HRP biosensor maintains the catalytic activity and is of considerable interest due to the simple procedure in practical applications and a promising platform for the lack of environmental monitoring for these contaminants.

SELECTIVE AND EFFECTIVE RECOVERY OF COPPER FROM PRINTED CIRCUIT BOARD SCRAPS

Copper was recovered from printed circuit boards (PCB) scraps by the combined mechanical and electrochemical method using 7M nitric acid as leaching agent followed by metal electrodeposition electrolyzing leachate. The metal recovery selectivity and effectivity were investigated through determination of electrodeposition potentials based on anodic stripping voltammetry (ASV). Linear sweep voltammetry (LSV) and cyclic voltammetry (CV) techniques were also used to reveal the optimized electrolysis parameters. The influence of various process parameters such as current density, pH, and temperature on electrodeposition efficiency was examined. The high recovery efficiency, more than 90 %, was reached for copper electrodeposition from PCB leachate at cathodic current density of 20 mA/cm2, pH=1 and temperature is 40 oC of the electrolyzer solution.

Fabrication of Mesoporous Cu Films on Cu Foils and Their Applications to Dopamine Sensing.

We previously succeeded to prepare stable mesoporous Cu films on Au-coated conductive working electrodes by using polystyrene-b-poly(oxyethylene) (PS63 000 -b-PEO26 000 ) micelles as template and sulfuric acid to increase ionic conductivity. In the present study, we report the preparation of mesoporous Cu films on Cu foil. By changing the Cu salts and electrodeposition potentials, we discuss how these parameters influence the final product. Without having to filtrate interefering species, such as uric acid, ascorbic acid and glucose, the dopamine concentration can be precisely determined by applying a suitable potential. Therefore, non-invasive electrochemical sensing based on mesoporous films will be useful for daily diagnosis of mental disorder.

Towards Higher Energy Density Redox‐Flow Batteries: Imidazolium Ionic Liquid for Zn Electrochemistry in Flow Environment

AbstractWe present the first demonstration of an ionic liquid electrolyte under a realistic flow environment for applications in redox‐flow batteries based on the Zn2+/Zn0 redox couple. An electrolyte mixture containing Zn(dca)2 and 3 wt % H2O in 1‐ethyl‐3‐methylimidazolium dicyanamide, [Emim][dca], ionic liquid was used to study the effects of Zn2+ concentration and flow rate on the Zn2+/Zn0 electrochemical performance as well as its impact on the morphology of the Zn deposit. An optimized Zn2+ concentration and flow rate were determined by using an in‐house‐designed 3D‐printed flow‐cell prototype. Surface characterization through SEM revealed that both the concentration and flow rate directly impact Zn morphology under flow conditions. The electrolyte mixture with a higher Zn(dca)2 concentration (18 mol %) showed favourable results; voltammetry showed higher peak current densities (100 mA/cm2 discharge current density) and more positive Zn electrodeposition potentials (−1.33 V vs Ag/AgOTf) coupled with higher cycling efficiency (45±3%) compared to those obtained with the lower Zn concentration system (9 mol %, −1.44 V vs Ag/AgOTf, 48 mA/cm2 discharge current density and 33±3% cycling efficiency).

Physical and electrochemical properties of ZnO films fabricated from highly cathodic electrodeposition potentials

The physical and electrochemical properties of zinc oxide (ZnO) film electrode that were prepared electrochemically were studied. ZnO was electrodeposited on ITO glass substrate by applying three different highly cathodic potentials (−1.3 V, −1.5 V, −1.7 V) in a solution containing 70 mM of Zn(NO3)2.xH2O and 0.1 M KCl with bath temperatures of 70 °C and 80 °C. The presence of ZnO was asserted from XRD analysis where the corresponding peaks in the spectra were assigned. SEM images revealed the plate-like hexagonal morphology of ZnO which is in agreement with the XRD analysis. The areal capacitance of the ZnO was observed to increase when the applied electrodeposition potential is increased from −1.3 V to −1.5 V. However, the areal capacitance is found to decrease when the applied electrodeposition potential is further increased to −1.7 V. The resistance of charge transfer (Rct) of the ZnO decreased when the applied electrodeposition potential varies from −1.3 V to −1.7 V due to the decreased particle size of ZnO when more cathodic electrodeposition potential is applied.

Studies on electrochemical deposition of novel Zn–Mn–Ni ternary alloys from an ionic liquid based on choline chloride

Ternary Zn–Mn–Ni alloy coatings were electrodeposited for the first time from a choline chloride based ionic liquid with the aim of collecting properties of binary Zn–Mn and Zn–Ni alloys into one alloy system. The effect of electrodeposition potential on the composition and corrosion performance of the obtained ternary Zn–Mn–Ni deposits was investigated and contrasted with the characteristics of Zn–Mn and Zn–Ni deposits. Cyclic voltammetry revealed that the deposition of ternary Zn–Mn–Ni alloys behaved differently from the deposition of binary Zn–Mn and Zn–Sn alloys and that Mn deposition takes place at positive potentials in the Zn–Mn–Ni electrolyte than in the Zn–Mn electrolyte due to the presence of Ni2+ ions in the electrolyte. X-ray diffraction studies showed that the Zn–Mn–Ni ternary alloys consist of a lattice of Zn (with Mn and Ni imbedded inside) at low electrodeposition potentials and MnZn(with Ni imbedded inside) phase at high electrodeposition potentials. Chemical composition analysis show that the Mn content in the ternary Zn–Mn–Ni alloy increased with increase in electrodeposition potential, whereas Zn and Ni contents are suppressed. The corrosion tests results indicate that through addition of Ni into the Zn–Mn binary alloy, the Zn–Mn–Ni alloy tailored are more corrosion resistant than the Zn–Mn binary alloy whilst the passivation behavior is still preserved.