Electrodeposition Of Silver Research Articles

Characterization and electrochemical analysis of silver electrodeposition in ChCl–urea deep eutectic solvents

Electrochemical reduction behaviours of silver ions in ChCl–urea deep eutectic solvents (DESs) were investigated by cyclic voltammetry. The results showed that equilibrium potential Eeq of the electrode system in ChCl–urea DESs was −0.112 V. The Tafel curve was used to obtain the exchange current density j0 = 2.92 ± 0.2 cm−2 and the transfer coefficient α = 0.16 ± 0.2. The nucleation and growth mechanism of silver were studied by cyclic current method. The results showed that electrodeposition consisted of two processes, 3D nucleation with diffusion-controlled growth j3D-dc(t) and a small amount of water in the reduction jWR(t). By calculating the percentage of different charge densities of j3D-dc and jWR, the contribution rate of different processes to the total current was analysed. With the increase in potential, the charge in water reduction process decreased, while the charge in silver 3D nucleation process increased. Scanning electron microscope and energy spectrum scanning were used to characterize the surface and section micro-morphologies of silver coating. The results showed that silver grew dendritically at −0.97 V, and the thickness was 22.98 μm. The results of X-ray photoelectron spectroscopy showed that silver coating was composed of Ag2O and Ag.

Electrodeposition of Silver–Graphene Films for Electronic Connectors in Succinimide Solutions

Silver is electroplated on the surface of connectors as a protective barrier layer in order to improve the corrosion resistance and to increase the durability of the connector. In this work, silver-graphene films were electrodeposited on copper–zinc alloy substrates from a succinimide silver-plating system in Hull-cell alkaline solutions by the addition of 0.4 g L–1 graphene oxide. The crystallographic structure and microstructure of the formed films were determined by X-ray diffraction and scanning electron microscopy, respectively. The corrosion resistance of the films was measured by a potentiodynamic polarization test. The results show that a low amount of graphene was incorporated into a silver deposit. The addition of graphene oxide could not influence the deposition rate and the crystallographic structure of the film, but resulted in a decrease in the size of aggregates or particles, compared with those of a pure silver film. The optimal current density was found to be 0.5 ~ 1.0 A dm–2, the surface of the films had a homogeneous close-packed fine-crystalline structure. The films were uniform, dense, and adherent to the substrate, without any evidence of delamination. At the same time, the addition of graphene oxide improved the corrosion resistance of silver films to a certain extent.

A Deep Eutectic Solvent as Leaching Agent and Electrolytic Bath for Silver Recovery from Spent Silver Oxide Batteries

It is shown for the first time that the deep eutectic solvent, DES, formed by acetylcholine chloride and urea can be successfully used for Ag recovery from the cathode powder of spent silver oxide batteries. This DES performs two important functions namely, as selective leaching liquor to extract Ag(I) ions from the remaining Ag2O, leaving intact the metallic Ag in the solid phase, and as electrolytic bath for silver electrodeposition onto a glassy carbon electrode or graphite. Using potentiodynamic and potentiostatic electrochemical measurements, it was possible to quantify both: the Ag(I) leaching rate and the concentration of Ag(I) ions leached after 24 h. From this value, it was possible to estimate that about 7% of the original mass of the cathode powder corresponds to Ag2O and the rest to metallic Ag. Moreover, from potentiostatic current density transients, recorded during Ag electrodeposition, it was shown, for the first time in this DES, that this process occurs via multiple 3D nucleation with diffusion-controlled growth and valuable practical information i.e. the diffusion coefficient of Ag(I) ions in this media was quantified. From scanning electron microscopy images and energy-dispersive X-ray spectroscopy, the morphology and composition of the resulting deposits were characterized.

Reflective‐Emissive Representation by Combining Ru(II)‐Complex‐Based Electrochemiluminescence and Localized‐Surface‐Plasmon‐Resonance‐Based Electrochromism

AbstractThis paper demonstrates a novel display device with four optical states: transparent, mirror, black coloration, and orange light emission. The device is constructed by sandwiching a gel electrolyte containing silver ions and a ruthenium (II) complex between a pair of indium tin oxide electrodes. The electrochemiluminescent orange emission from the ruthenium (II) complex is obtained by applying alternative current (AC) voltage. In contrast, the application of direct current (DC) voltage results in the mirror state due to silver electrodeposition. Moreover, the DC application of a higher voltage results in the device exhibiting the black state owing to the distribution of size and roughness of the silver nanoparticles (NPs) on the indium tin oxide electrode. Both the reflective states reverted to their initial transparent state, owing to the dissolution of silver deposits during the DC application of oxidative voltage of silver NPs.

Electrodeposition of silver onto carbon graphite and their catalysis properties toward thiamethoxam reduction: application in food and beverage samples

The purpose of this paper is the electrodeposition of silver particles on graphite electrode (Ag@GrCE) using chronoamperometry and the use of this electrode for the determination of thiamethoxam. The electrode was prepared by chronoamperometry and characterized by X-Ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), EDX analysis and electrochemical impedance spectroscopy. The obtained electrode exhibits excellent electrocatalytic activity toward thiamethoxam reduction. The voltammetric response was linear as function of TXM concentration with a limit of detection around to 1.92 × 10−6 mol L−1. The proposed electrode was successfully used to analyze thiamethoxam residue in some food samples including orange and tomato juices.

Improvement of Color Purity in Silver Electrodeposition-Based Multicolor Electrochromic Device

Electrochromism (EC) is defined as a reversible color change by electrochemical redox reaction and has several features such as color variation, memory property and so on. Multifunctional electrochromic materials which control multiple colors, various color density, and specular reflection are expected to be potential candidate for energy saving light-modulation device such as smart window and novel reflective display device such as e-paper.We reported silver electrodeposition–based EC device achieving three optical states -transparent, silver-mirror and black- in a single cell.1 Its mechanism was based on the electrodeposition of silver nanoparticles on two facing transparent electrodes, a flat ITO electrode and an ITO particle modified electrode. The EC material, gel electrolyte containing silver ion, was sandwiched by the two electrodes. The device’s default state was transparent, whereas, applying a negative voltage of -2.5 V to one or the other electrode causes the electrodeposition of silver on its surface. When silver was deposited on the flat ITO electrode, the device turns mirror. On the other hand, when silver was deposited on the rough ITO particle modified electrode, the device turns black. The image retention property (memory property) can be improved by inserting ion-exchange membrane2 or by using redox active counter electrode.3 Electrodeposition is an attractive method to create colors because silver nanoparticles exhibit various optical states based on their localized surface plasmon resonance (LSPR). LSPR bands of metal nanoparticles are affected by the size and shape.4 The control of LSPR, therefore, must enable dramatic changes in color for the surface where nanoparticles are deposited. We successfully demonstrate the first LSPR based multicolor EC device enabling reversible control of six optical states such as transparent, silver mirror, cyan, magenta, yellow and black, which is attractive for smart window as well as color e-paper application.5, 6 In this paper, we optimized composition of the EC solution and condition of step voltage application. As a result, we newly enabled silver electrodeposition-based multicolor EC device to achieve the improvement of color purity and green color representation in addition to magenta, cyan and yellow states (Figure 1). In order to discuss the relationship between the morphologies of the electrodeposited silver nanoparticles and the device color, we carried out field emission scanning electron microscopy (FE-SEM) analysis of silver-deposited electrodes and finite-difference time-domain (FDTD) calculation of silver nanoparticles’ models.

Modelling Nucleation during Electrodeposition By Model Method. Parametric Identification Considering Agitation By Rde or Ultrasound

Nowadays, 40% of the world wide used energy is provided by electric power and this share should reach about 60% by 2040. For environmental reasons, it is crucial to ensure low dissipation loss in power electronic devices by optimizing energy conversion. In the field of renewable energies and automotive electronics, possible energy savings are estimated to be between 20 and 35%. For that purpose, innovative power components and modules are required, with a growing interest for fast and simple joining processes in their fabrication management, in the case for example of the assembly of large-size double-side cooled modules. Several options are possible, including free sintering of metallic pastes or electroforming welding. In all cases, this requires a great control of both surfaces to be joined, mostly prepared by electrodeposition (microstructure, porosity, alloy composition). But the final properties of electrodeposited coatings are strongly dependent of the first nucleation steps, which influence the whole layer structure. In this frame, the modelling of a nucleation process followed by diffusion limited three dimensional growth is an area of promising interest. The study of potentiostatic current transients is a relevant methodology, allowing the determination of several parameters such as nucleation rate, nucleus density, and number of active sites. Different competing models are available, such as Scharifker and Hills [1] and Scharifker and Mostany [2]. By using the model method i.e. the identification of the model parameters by error minimization, it is possible to reach an accurate description of the first layer growth in the case of different metals such as silver and copper. Nevertheless, little attention have been paid to changes in hydrodynamic conditions, for example in the study of current response under forced convection [3]. The present work describes the extension of the model method to the modelling of the first steps of nucleation growth in the case of a sample exposed to an ultrasonic irradiation, which was compared to forced convection induced by a rotating disc electrode at the very same agitation level (equivalent velocity [4,5]. Eventually, the case of electrodeposited alloys was examined, as a function of their Brenner classifications (anomalous and normal codeposition [6]). The limitation of the data processing by the numerical approach are also discussed.[1] Scharifker, B. & Hills, G. Theoretical and experimental studies of multiple nucleation. Electrochimica Acta 28, 879–889 (1983).[2] Scharifker, B. R. & Mostany, J. Three-dimensional nucleation with diffusion controlled growth. J. Electroanal. Chem. Interfacial Electrochem. 177, 13–23 (1984).[3] Hyde, M. E. & Compton, R. G. Theoretical and experimental aspects of electrodeposition under hydrodynamic conditions. J. Electroanal. Chem. 581, 224–230 (2005).[4] Pollet B.G., Hihn J.-Y., Doche M.L, Mandroyan A., Lorimer J.P., Mason T.J “Transport limited currents close to an ultrasonic horn: equivalent flow velocity determination”, Journal of Electrochemistry Society, 154(10), E131-E138, (2007)[5] A. Nevers, L. Hallez, F. Touyeras, J.-Y. Hihn, Effect of ultrasound on silver electrodeposition: Crystalline structure modification, Ultrason. Sonochem. 40 (2018)[6] Brenner, A. Electrodeposition of alloys. Principles and practice Volume II, (1963). Figure 1

Chelating agents effects in nanoengineered silver structures over TiO2 nanotubes on Ti wires and their Rhodamine B detection activity

The influence of chelanting agents in nanoengineered silver structures was investigated and, subsequently, the study aimed to access the viability of the electrodeposition process of silver over anodized titanium dioxide nanotubes (TNT) on titanium wires as SERS substrate to detect Rhodamine B (RhB). Firstly, a titania layer composed of nanotubular structures were synthesized from Ti wires, which was annealed to obtain the anatase crystalline phase. These samples were then submitted to a silver electrodeposition, employing diethylenetriaminepentaacetic acid (DTPA) and disodium ethylenediaminetetraacetic acid (Na2EDTA) as chelanting agents. The results confirmed the successful synthesis of silver dendrites by using DTPA enriched electrolytes, while by Na2EDTA the silver structures present a nanoparticulate shape (AgNP). Moreover, in the absence of chelating agents, the samples do not show any evidence of silver structures formation. Overall, for the detection test with Rhodamine B, the sample containing Na2EDTA showed the most remarkable signal. These characteristics may be related to the nanoparticulate structure and the dendrites thickness layer over titanium dioxide nanotubes. The synthesized AgNP/TNT over wires may be considered potential sensors to improve the detection of RhB.

Electrodeposition of Silver in a Ternary Deep Eutectic Solvent and the Electrochemical Sensing Ability of the Ag-Modified Electrode for Nitrofurazone.

The determination of nitrofurazone (NFZ) has received substantial attention because it is a kind of antibiotic drug. Herein, a rapid and low-cost electrochemical sensor for the analysis of NFZ is reported. The method uses Ag-modified electrodes in which different surfactants, hexadecyltrimethylammonium bromide and sodium dodecyl sulfate, in a ternary choline chloride-urea-glycerol deep eutectic solvent were deposited. The physical properties of the solutions with various surfactants are investigated by a conductivity meter, viscometer, and tensiometer. The morphologies and crystallinity of the Ag-modified electrodes were characterized by using scanning electron microscopy, transmission electron microscopy, and powder X-ray diffraction. Electrochemical impedance spectroscopy and CV analyses indicate that the as-prepared Ag-SDS electrode exhibited better performance as a NFZ sensor. The dynamic linear range of NFZ is 0.66-930 μM with a corresponding detection limit of 0.37 μM. The proposed electrochemical sensor was applied to detect NFZ in the aquaculture water sample, and the results showed good recovery in the range from 100.28 to 102.65%.

Simultaneous Electrodeposition of Silver and Tungsten from [EMIm]Cl:AlCl3 Ionic Liquids outside the Glove Box

Ag–W two-phase system was prepared by electrodeposition using anhydrous 1-ethyl-3-methylimidazolium chloride [EMIm]Cl ionic-liquid (IL) solution with AlCl3 in different ratios. The deposition took place outside the glove box with a continuous Ar stream over the electrolyte at 120 °C and a pulsed-like current regime. Resultant layers show areas of Ag and W with an overall W content with a mass fraction of w W = 50% (mole fraction x W = 36.9%). The phase composition of Ag–W layers was observed by X-ray diffraction, and the chemical composition was characterized by scanning electron microscopy and inductively coupled plasma optical emission spectroscopy.

Electrodeposition of silver from the ionic liquid Butylpyridinium dicyanamide

The electrodeposition of silver was performed on a platinum electrode from a non-fluorinated ionic liquid (IL), butylpyridinium dicyanamide (Pyri4-DCA). The as-studied IL is characterized by a high ionic conductivity (11.03 mS.cm−1) and a low dynamic viscosity (24.4 mPa.s), which are appropriate for the electrodeposition process. The cyclic voltammetry (CV) curves recorded in Ag-DCA/Pyri4-DCA solutions showed the presence of reduction and oxidation peaks, respectively associated with the deposition and stripping of silver from the Pt surface. The diffusion coefficient of Ag(I) calculated from CV curves varied from 5.3 10−7 to 1.1 10−7 when Ag+ concentration was changed from 1 to 10 mM. The silver was electrodeposited on the Pt surface at different constant potentials. The nuclei size and population density of silver were monitored by varying the electrolyte concentration, the applied potential and the deposition time. From the analysis of the experimental transient curves, it was shown that the electrochemical deposition process of silver follows a 3D nucleation with diffusion-controlled growth. The nuclei population densities and diffusion coefficients were also determined for various chronoamperometric parameters by using the fitting model of Scharifker and Hills for 3D nucleation and growth.

Silver electrodeposition at room temperature protic ionic liquid 1-H-methylimidazolium hydrogen sulfate

Silver electrodeposition is essential for industry and commerce, such as aesthetical products or electronic devices, and is regularly carried out in strongly corrosive and toxic alkaline cyanide baths. This paper introduces a methodology using the room temperature protic ionic liquid (RTPIL) 1-H-3-methylimidazolium hydrogen sulfate [HMIM+][HSO4−] as the electrolyte for silver electrodeposition on a gold disk electrode. Cyclic voltammograms for the Ag+/Ag pair show one process for Ag reduction (cathodic peak potential, Ecp = −0.06 V vs. Ag wire) and oxidation (anodic peak potential, Eap = 0.06 V vs. Ag wire), being then a quasi-reversible process. The temperature effect over Ag+ ions electrodeposition shows to be limited above 45 °C due to the equilibrium between Ag+ cations and HSO4− anions brought by RTPIL, a hypothesis that can be found in the literature for similar systems. Cottrell plots were obtained in different temperatures to calculate the Ag+ diffusion coefficient in [HMIM+][HSO4−] RTPIL. The diffusion coefficient changes nonlinearly when temperature increased, and the Arrhenius-type plot for this system is convex (i.e., not linear and dependent upon other quantity). This fact leads to a polynomial fit for the Arrhenius-type plot rather than linear, and the activation energy is dependent upon temperature. This dependency is related to the equilibrium hypothesis, which is further confirmed by DFT calculations. The formation constant of the AgHSO4 complex has a negative Gibbs energy, and this thermodynamic calculation shows to be exergonic. The morphology of Ag electrodeposits changes when temperate, and deposition mode (potentiostatic and galvanostatic) change, varying the bulk layer and sub-micrometer Ag morphologies.

A Self‐contained Two‐electrode Nanosensor for Electrochemical Analysis in Aqueous Microenvironments

AbstractWe describe the development, fabrication, and characterization of a novel two‐electrode nanosensor contained within the tip of a needle‐like probe. This sensor consists of two, vertically aligned, carbon structures which function as individual electrodes. One of the carbon structures was modified by silver electrodeposition and chlorination to enable it to function as a pseudo‐reference electrode. Performance of this pseudo‐reference electrode was found to be comparable to that of commercially available Ag/AgCl reference electrodes. The unmodified carbon structure was employed as a working electrode versus the silver‐plated carbon structure to form a two‐electrode sensor capable of characterizing redox‐active analytes. The nanosensor was demonstrated to be capable of electrochemically characterizing the redox behavior of para‐aminophenol (PAP) in both bulk solutions and microenvironments. PAP was also measured in cell lysate to show that the nanosensor can detect small concentrations of analyte in heterogenous environments. As the working and reference electrodes are contained within a single nanoprobe, there was no requirement to position external electrodes within the electrochemical cell enabling analysis within very small domains. Due to the low‐cost manufacturing process, this nanoprobe has the potential to become a unique and widely accessible tool for the electrochemical characterization of microenvironments.

The medium effect on electrodissolution of adsorbed or suspended Ag nanoparticles

Electrochemical behaviour of six types of Ag nanoparticles (three stabilised by citrate and three others stabilised by polymers) was studied on carbon screen-printed electrode and glassy carbon rotating disc electrode. A stationary electrode was used as a support for adsorbed nanoparticles, whereas the rotating disc electrode was applied for experiments in nanoparticles suspension. Peak shaped cyclic voltammograms obtained for immobilised nanoparticles indicate their electro-dissolution and electrodeposition of silver in the backward scan. The given peak shape and its position on potential scale depend both on the type of nanoparticles and the supporting electrolyte. When aggregation of Ag nanoparticles was detected by UV–vis spectroscopy, splitting of an anodic peak corresponding to electrodissolution of silver in neutral phosphate buffer or NaOH solution is seen. Injection of a fraction of microgram of Ag nanoparticles was detected in chronoamperometric experiments on rotating disc electrode. However, in the presence of H2O2, the effect of nanograms of silver was seen on voltammetric curve indicating electrocatalytic amplification.

Modelling Nucleation during Electrodeposition By Model Method. Parametric Indentification Considering Agitation By Rotating Disc Electrode or Ultrasound

Nowadays, 40% of the world wide used energy is provided by electric power and this share should reach about 60% by 2040. For environmental reasons, it is crucial to ensure low dissipation loss in power electronic devices by optimizing energy conversion. In the field of renewable energies and automotive electronics, possible energy savings are estimated to be between 20 and 35%. For that purpose, innovative power components and modules are required, with a growing interest for fast and simple joining processes in their fabrication management, in the case for example of the assembly of large-size double-side cooled modules. Several options are possible, including free sintering of metallic pastes or electroforming welding. In all cases, this requires a great control of both surfaces to be joined, mostly prepared by electrodeposition (microstructure, porosity, alloy composition). But the final properties of electrodeposited coatings are strongly dependent of the first nucleation steps, which influence the whole layer structure. In this frame, the modelling of a nucleation process followed by diffusion limited three dimensional growth is an area of promising interest. The study of potentiostatic current transients is a relevant methodology, allowing the determination of several parameters such as nucleation rate, nucleus density, and number of active sites. Different competing models are available, such as Scharifker and Hills [1] and Scharifker and Mostany [2]. By using the model method i.e. the identification of the model parameters by error minimization, it is possible to reach an accurate description of the first layer growth in the case of different metals such as silver and copper. Nevertheless, little attention have been paid to changes in hydrodynamic conditions, for example in the study of current response under forced convection [3]. The present work describes the extension of the model method to the modelling of the first steps of nucleation growth in the case of a sample exposed to an ultrasonic irradiation, which was compared to forced convection induced by a rotating disc electrode at the very same agitation level (equivalent velocity [4,5]. Eventually, the case of electrodeposited alloys was examined, as a function of their Brenner classifications (anomalous and normal codeposition [6]). The limitation of the data processing by the numerical approach are also discussed.[1] Scharifker, B. & Hills, G. Theoretical and experimental studies of multiple nucleation. Electrochimica Acta 28, 879–889 (1983).[2] Scharifker, B. R. & Mostany, J. Three-dimensional nucleation with diffusion controlled growth. J. Electroanal. Chem. Interfacial Electrochem. 177, 13–23 (1984).[3] Hyde, M. E. & Compton, R. G. Theoretical and experimental aspects of electrodeposition under hydrodynamic conditions. J. Electroanal. Chem. 581, 224–230 (2005).[4] Pollet B.G., Hihn J.-Y., Doche M.L, Mandroyan A., Lorimer J.P., Mason T.J “Transport limited currents close to an ultrasonic horn: equivalent flow velocity determination”, Journal of Electrochemistry Society, 154(10), E131-E138, (2007)[5] A. Nevers, L. Hallez, F. Touyeras, J.-Y. Hihn, Effect of ultrasound on silver electrodeposition: Crystalline structure modification, Ultrason. Sonochem. 40 (2018)[6] Brenner, A. Electrodeposition of alloys. Principles and practice Volume II, (1963). Figure 1

A new method to produce graphite decorated by electrodeposited metal: The case of silver electrodeposition process inside a graphite paste electrode

The results reported in this paper deal with the investigation of the silver electrodeposition process inside a modified graphite paste (MGP). Thus, a new method to produce graphite decorated with electrodeposited metal was proposed that could be used in modified electrodes with renewable surface by polishing. The electrodeposition process was made inside of the MGP (graphite, AgNO3, NaCl and mineral oil) inserted in the tip of a polypropylene syringe with copper wire electrical contact (working electrode, MGPE). Voltammetric study with the MGPE in NaCl aqueous solution indicated that the silver reduction occurred by two different processes at potentials more negative than 0.000 V and −0.150 V and exhibited one anodic peak for silver oxidation. These cathodic processes were dependents of the AgNO3 concentration and NaCl added. It was concluded that the silver reduction occurs mainly in the nearest layer of the MGP/NaCl solution interface, decreasing in direction to the MGP interior. Scanning electron microscopy (SEM) photographs indicated that the silver electrodeposition occurred on some graphite flakes with a homogeneous silver layer, showing also additional morphological features depending on the electrodeposition condition. Transmission electron microscopy (TEM) image showed nanometric electrodeposited silver. X-ray diffraction (XRD) analysis showed diffraction lines for polycrystalline silver.

Indirect (hydrogen-driven) electrodeposition of porous silver onto a palladium membrane

Hydrogen permeation through a pure palladium film (25 μm thickness, optically dense) is employed to trigger electron transfer (hydrogen-driven) reactions at the external palladium | aqueous electrolyte interface of a two-compartment electrochemical cell. Two systems are investigated to demonstrate feasibility for (i) indirect hydrogen-mediated silver electrodeposition with externally applied potential and (ii) indirect hydrogen-mediated silver electrodeposition driven by external formic acid decomposition. In both cases, porous metal deposits form as observed by optical and electron microscopies. Processes are self-limited as metal deposition blocks the palladium surface and thereby slows down further hydrogen permeation. The proposed methods could be employed for a wider range of metals, and they could provide an alternative (non-electrochemical or indirect) procedure for metal removal or metal recovery processes or for indirect metal sensing.Graphical abstract

Shape-controlled electrodeposition of silver using chitosan as structure-directing agent on disposable pencil graphite electrodes: low-cost electrocatalysts for the detection of hydrogen peroxide and hydrazine hydrate

A facile synthetic protocol for the electrodeposition of diverse morphologies of silver on disposable pencil graphite electrodes (Ag/PGE) in the presence of chitosan as structure-directing agent (SDA) is reported. The influence of various electrodeposition parameters on the morphology of Ag deposited has been studied and interpreted using electron microscopic techniques. Several impressive morphologies such as hexahedron, leaf and dendrites have been observed for Ag/PGE with respect to change in experimental conditions. Furthermore, the crucial role of chitosan in determining the morphology of Ag/PGE has been elucidated with the help of three-dimensional Scharifker-Hills nucleation and growth model. The electrocatalytic activities of various Ag/PGEs towards the reduction of hydrogen peroxide (HP) and oxidation of hydrazine hydrate (HH) have been studied in detail with the help of diverse electrochemical techniques. In comparison with PGE, the Ag hexahedron- (Ag-Hex/PGE) and Ag dendrite- (Ag-Dend/PGE) modified PGEs exhibited excellent electrocatalytic activity towards HP and HH, respectively. The Ag-Hex/PGE displayed a wide linear range of 0.1–20,000 μM with a limit of detection (LOD, 3σ/m) of 0.06 μM for HP reduction. On the other hand, a linear range of 25–20,000 μM with LOD of 1.8 μM for HH oxidation has been observed for Ag-Dend/PGE. Furthermore, the modified Ag/PGEs revealed remarkable reproducibility and long-term storage stability. The practical applicability of the Ag-Hex/PGE and Ag-Dend/PGE was demonstrated through the electrocatalytic detection of HP in milk and HH in tap water samples with satisfactory recovery results.

A comparative study of silver electrodeposition from pyrophosphate-cyanide and high concentration cyanide electrolytes in the presence of brighteners.

A study of the electrodeposition of silver from 2 different types of electrolytes; (1) neutral pyrophosphatecyanide electrolyte and (2) alkaline high concentrated cyanide electrolyte in the presence of a variety of additives such as 2-mercaptobenzothiazole, potassium selenocyanate, and potassium antimony tartrate was performed. Influence of additives and cyanide concentration on microstructure and kinetics of the cathodic processes were studied. A brightener couple, 2-mercaptobenzothiazole and potassium antimony tartrate, were combined within this investigation and detected to be highly effective for silver electrodeposition. The rapid increase in current density at the same potential interval related to grain refinement effect of potassium antimony tartrate was shown. The cyclic organic compound, 2-mercaptobenzothiazole, polarizes the reduction to high cathodic potential in pyrophosphate electrolyte. However, the sufficient levelling effect required for the mirror-bright appearance seems to be related to the high polarizing effect of the high concentration cyanide content. In the case of pyrophosphate electrolytes, sufficient levelling cannot be achieved, so semigloss coatings are obtained. The low cathodic potential electrodeposition of silver in pyrophosphate electrolyte, which is found to proceed by 3D instantaneous nucleation, is polarized to high cathodic potentials and grows into 3D progressive nucleation and diffusion-controlled growth in high concentration cyanide electrolyte.

Tunable Fractal Nanostructures for Surface-Enhanced Raman Scattering via Templated Electrodeposition of Silver on Low-Energy Surfaces

Here, we demonstrated a facile method for growing nanofeatured silver (Ag) structures on a planar microelectrode platform. The nanostructures were assembled along the electrically insulating substrate, growing from the microelectrode edge with the electrodes acting as the template. This was done by (a) limiting the nucleation to the edges of the electrodes and (b) chemically functionalizing the insulating substrate to promote an interaction between itself and the growing metallic structures. These structures were able to reach lateral lengths greater than 100 μm. Additionally, we performed an extended investigation into how the nanostructure morphology can be changed from spherical aggregates to fractal dendrites by altering the electrical signal and solution composition. We determined citrate to be a necessary additive and showed that it acts as a supporting electrolyte, capping agent, and oxidizing/complexing agent. Next, using optimal deposition conditions, we assembled Ag surface-enhanced Raman scattering (SERS) substrates with an enhancement factor up to 4.55 × 106. Finally, we demonstrated how these SERS nanostructures can also serve as concentration amplification devices, accelerating analyte deposition onto the detection site by means of electrohydrodynamics.