DC Electrodeposition Research Articles

Photoluminescence Characterization of Cadmium Sulphide (CdS) Nanowires for Polarization Studies

In this paper, the polarizing properties for CdS nanowire arrays were explored for their potential use in the design of nanowire based polarizers and optical switches. These free standing cadmium sulphide (CdS) nanowires were grown in anodized aluminum oxide (AAO) template via dc electrodeposition. Raman and photoluminescence (PL) measurements were investigated for parallel and perpendicular polarization with two orientations of the sample having light propagating parallel to the nanowire axis in one orientation and light propagating perpendicular to the nanowire axis in other orientation. Polarization-sensitive measurements show strong polarization anisotropy in the photoluminescence (PL) intensity measurements observed in parallel and perpendicular orientation to the long axis of a nanowire. The measured PL ratio, ρ, for parallel to perpendicular orientation was around 0.80- 0.85 which shows strong polarization anisotropy for the grown CdS nanowires. Strong peaks of A1 (TO) at 235 cm-1, E2 mode at 255 cm-1 along with 1 LO (longitudinal optical) at 303 cm-1, 2 LO peak at 604 cm-1 of the CdS nanowires were seen with different polarizations for Raman spectral studies. These polarization studies show that these dc electrodeposited grown CdS nanowire arrays are well suited for uses in polarization-based nanoscale devices such as in optical switches, and high performance photodetectors.

Electrodeposition and Characterization of Ni–W–Cr2O3 Nanocomposite Coating

In this paper, compact Ni–W and Ni–W–Cr2O3 nanocomposite coatings were deposited on mild steel substrates by DC electrodeposition method. The surface morphology, elemental composition, and structure of the obtained coatings were investigated by scanning electron microscopy, energy dispersive spectrometer, and x-ray diffraction. The corrosion resistance was evaluated by potentiodynamic polarization (Tafel) and electrochemical impedance spectroscopy. It is shown that incorporation of Cr2O3 nanoparticles into amorphous Ni–W coating would transform its structure into crystalline and influence its properties. The microhardness of Ni–W–Cr2O3 nanocomposite coatings (717–764 HV0.1) is significantly bigger than that of Ni–W coating (687 HV0.1). In addition, with increase of Cr2O3 addition in the electroplating bath, a tendency of improvement in hardness and corrosion resistance performance is observed. Finally, an excellent Ni–W–Cr2O3 nanocomposite coating with a slightly lower resistance and much higher hardness compared with Ni–W coating is electrodeposited in the bath containing 20 g/L Cr2O3 nanoparticles.

The effects of duty cycles on pulsed current electrodeposition of Zn[sbnd]Ni[sbnd]Al2O3 composite on steel substrate: Microstructures, hardness and corrosion resistance

In this study, we examine the effect of duty cycles (33%, 50% and 67%) under square-wave galvanostatic pulses on the electrodeposition of zinc-nickel-alumina (ZnNiAl2O3) composites from a sulfate bath. XRD results showed that the dominant phases of the ZnNiAl2O3 electrodeposits were mixtures of Zn21Ni5 and Zn22Ni3 phases together with as Al2O3. The Ni content measured in the electrodeposits using EDS varied from 9.73 to 13.47 wt%. SEM results showed that finer and smoother surface electrodeposits were obtained by pulsed current electrodeposition at a low (33%) duty cycle. In addition, the corrosion properties of the electrodeposits were characterized by Tafel plots and electrochemical impedance spectroscopy (EIS), while the microhardness of the electrodeposits was measured by a Vickers hardness tester. In summary, this study revealed that pulsed current electrodeposition at a 33% duty cycle led to a finer and smoother surface morphology, an enhanced strength, a greater corrosion resistance, and a higher Ni content in the ZnNiAl2O3 composite coatings compared to plating at higher duty cycles or plating through DC electrodeposition.

Microstructural stability and phase transformations in electrodeposited cobalt-phosphorus coatings

Electrodeposited Co-P coatings are a potential replacement for electrolytic hard chrome coatings in critical engineering applications. The superior performance of the Co-P coatings is derived from as-deposited microstructures consisting of metastable crystalline and amorphous phases. These microstructures depend upon the deposition conditions and, in particular, on the P content. In this study, Co-P coatings with P contents of 6.4–28.4 at.% were produced by DC electrodeposition onto low alloy steel coupons. The coatings were characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The initial deposit microstructures are either crystalline (<10.0 at.% P), hybrid crystalline/amorphous (10.0–12.1 at.% P) or amorphous (>12.1 at.% P). The thermal signatures within each microstructural class were determined by DSC to identify the temperatures at which transformations occur in these metastable microstructures. The transformation products were then identified by XRD and TEM on samples of the deposits annealed isothermally in the DSC. These data show that: the crystalline deposits transform to an equilibrium mixture of HCP-Co and Co2P by precipitation of the phosphide from the initially supersaturated HCP-Co; the amorphous deposits crystallize to form a mixture of metastable FCC-Co and Co2P; and the hybrid deposits transform to a mixture of the products observed for the crystalline and amorphous deposits. The activation energies of the processes involved were obtained by Kissinger analysis on the scan-rate dependence of the peak temperatures in the DSC curves. The transformation mechanisms were then deduced by comparing these values with published values for such systems in the literature.

Investigation of easy axis transition and magnetodynamics in Ni76Fe24 nanowires and Ni77Fe23 nanotubes synthesized by DC electrodeposition

Well rounded, smooth and elegantly elongated Ni76Fe24 nanowires and Ni77Fe23 nanotubes were successfully fabricated inside the home made anodized aluminum oxide (AAO) templates at room temperature by cost effective DC electrodeposition. In order to explore surface information and atomic percentage, samples were characterized by scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) respectively. It is observed that highly homogeneous and uniform nanowires with Length = 10 μm and diameter = 50 nm and nanotubes with Length = 8 μm and diameter = 50 nm are formed. Different magnetic parameters i.e. M-H curves, coercivity (Hc), saturation magnetization (Ms) and magnetization reversal mode were also investigated by vibrating sample magnetometer (VSM). It is observed from angular dependence of coercivity that magnetization reversal mechanism occurs by nucleation mode in Ni76Fe24 nanowires and combination of curling and nucleation in Ni77Fe23 nanotubes. Different magnetic interactions were ruled out with the help of delta M curves. It is found that dipole-dipole interactions dominate over shape anisotropy due to which the easy axis entirely re-oriented towards the perpendicular from the wire and tube axis. Furthermore this fact of easy axis transition was also confirmed by Ferromagnetic resonance (FMR) performed at frequency f = 9.8 GHz by sweeping magnetic field from parallel to perpendicular of nanocylinder axis. The ferromagnetic relaxation mechanism is explained on the basis spin–orbit interaction and s–d interaction mechanism using LLG equation. The MH loops of Ni77Fe23 nanotubes at low temperature confirms that thermal energy decreases at low temperature causing an increase in saturation magnetization. This study will be useful for the application of nanocylinders in various Spintronics devices.

RETRACTED: The Study of Composition and Morphology of Pd-Ag Alloy Powders by Electrodeposition

Pd-Ag alloy powders were prepared on the stainless steel by DC electrodeposition. Cyclic voltammetry found the reduction potential of Pd, Ag and Pd-Ag. The composition and morphology of Pd-Ag were investigated by means of SEM, EDS.

Fabrication and magnetic investigations of highly uniform CoNiGa alloy nanowires

CoNiGa ternary alloy nanowire arrays were successfully fabricated by simple DC electrodeposition into the anodized aluminum oxide (AAO) templates. A systematic study of the potential and components of the electrolyte were conducted to obtain different components of CoNiGa nanowires. The largest Ga content in the prepared alloy nanowires was about 17%, while for Co and Ni contents which can be controlled in a wide range by adjusting the composition and pH value of the electrolyte appropriately. X-ray diffraction analysis confirmed that the as-grown CoNiGa nanowire arrays were polycrystal with fcc phase of Co where Co atoms partially substituted by Ni and Ga. Magnetization curves of samples with different composition were measured at room temperature as well as low temperature. The results showed that the components of the alloy nanowires have a great impact on its magnetic properties. For Co55Ni28Ga17 nanowires, the magnetization reversal mode changes from curling mode to coherent rotation as the angle increases, and the temperature dependence of coercivity can be well described by the thermal activation effect.

Pulse DC electrodeposition of Zn–Ni–Co coatings

Anomalous co-deposition of Zn–Ni–Co ternary alloy on carbon steel and copper substrates was attempted using pulse direct current electrodeposition technique. The obtained coatings were characterised for their crystal structure, chemical composition and surface morphology by X-ray diffractometry, energy dispersive X-ray spectroscopy and scanning electron microscopy, respectively. X-ray diffraction measurement showed peaks for Zn, Ni and Co. The concentration of Ni and Co in the ternary alloy increased with decrease in pulse frequency as confirmed by energy dispersive X-ray measurement. Scanning electron microscopy revealed uniform morphology of the coating surface with an average grain size of 1 µm. Potentiodynamic polarisation and electrochemical impedance spectroscopy tests conducted in 3% NaCl solution confirmed improved corrosion behaviour of the coatings deposited at lower current pulse frequencies.

Template-Assisted Electrochemical Synthesis of p-Type InSb Nanowires

We report on the growth of Sb-rich indium antimonide (InSb) nanowires fabricated by dc electrodeposition in the pores of a gold-coated nanoporous anodic alumina oxide (AAO) template. An explanation of the various mechanisms of mass transport during successive stages of the growth process is also presented with experimental results confirming these growth stages. The 100 nm thick InSb nanowires that were grown using an electrolyte of pH 1.7 were found to be rich in antimony (Sb). The electrical properties of a single InSb nanowire was investigated by connecting the nanowire in a field-effect-transistor type configuration. The nanowires showed p-type conduction with a hole concentration of ∼ 1.9 × 1016 cm− 3 and field effect hole mobility of ∼ 507 cm2V− 1s− 1. The device had a high on-off current ratio of the order of 103. Temperature-dependent transport measurements showed thermally activated Arrhenius conduction in the temperature range from 200–325 K, yielding an activation energy of 0.1 eV. The ability to obtain high density of p-type InSb nanowires without addition of any dopants opens up new opportunities for using these nanowires in fabrication of electronic devices.

Corrosion and Properties of Developed Ni-CeO2 Co-deposited on Mild Steel at Varying Current Densities

Rare earth Nickel composite film was attempted on mild steel surface by DC electrodeposition for improvement of corrosion resistance and morphological structure. A conventional Watts bath was utilised for film fabrication and rare earth cerium oxide particle reinforcement were made at 5g/l CeO2 addition to the plating bath. The effect of varying current density (1.0-2.0 A/dm2) on coating morphology was studied by a Scanning Electron Microscope (SEM) and Linear polarization technique for corrosion resistance studied in 3.65% simulated saline environment (Cl− nature). Coatings exhibited improved corrosion resistance compared to pure Nickel coatings. Increase in current density was observed to result in improved resistance to corrosion. SEM/EDX results revealed presence of Ce metal in coating owing to the inclusion of CeO2 particles in plating bath and evidence of particle agglomeration.

Fabrication, morphological, structural and magnetic properties of electrodeposited Fe3Pt nanowires and nanotubes

Highly ordered Fe3Pt nanowires (NWs) and nanotubes (NTs) embedded in anodic aluminum oxide (AAO) template have been fabricated by dc electrodeposition method. Response of heat treatment on structural and magnetic properties of the samples has been studied with and without the presence of magnetic field (1T). X-Ray Diffraction analysis shows chemically ordered L12 face centered cubic (FCC) as the dominant phase for Fe3Pt NWs and heat treatment improves crystallinity with retained its phase. Whereas, Fe3Pt NTs show amorphous behavior with and without magnetic field annealing. Furthermore, magnetic properties of the samples have been investigated by vibrating sample magnetometer (VSM). Magnetic parameters of Fe3Pt including magnetic coercivity, saturation magnetization, squareness and shape of MH-loops have been investigated as a result of simple and MF annealing.

Magnetization Reversal and Surface Spins in Electrodeposited Co90Mn10 Alloy Nanowires

In this work, Co1−XMnX(X= 10) nanowires have been prepared by DC electrodeposition into anodized aluminum oxide (AAO) templates. A systematic study has been done about the effects of nanowires composition on the shapes of MH curves and magnetic properties. It is observed from XRD pattern that Co90Mn10 nanowires have polycrystalline structure with dominant FCC Cobalt phase. The M-H curves at two angles between magnetic field and nanowires axis define a clear and sharp anisotropic behavior. The magnetization reversal mechanism is found to be curling mode for certain angle between applied magnetic field and nanowires axis and then by nucleation mode. In order to elucidate the transition temperature, temperature dependent magnetization properties for Co90Mn10 nanowires at different applied fields have also been measured. The transition temperature or freezing temperature is found to be 350 K. The bifurcation of FC and ZFC curves is explained by the freezing of the surface spins, depinning of the domain walls and superparamagnetic nanoparticles on the surface of the nanowires.

Polymeric-Metal Oxide Nanostructures As Future Materials for Energy Applications

One of the most important directions of global research centers are studies on issues related to the acquisition, conversion and energy storage. Currently, more and more work is devoted to research on nanostructured materials as building blocks of batteries and electrochemical capacitors. Electrochemical capacitors (ECs) are energy storage devices which can find applications ranging from portable electronics to hybrid vehicles and large scale power generations. The ECs offer a number of desirable properties, such as fast charging (within seconds), reliability, long-term cycling (more than 500.000 cycles), and the ability to deliver 10 times more power than batteries. Moreover ECs can be used to recovery energy from repetitive processes (descending elevators, braking cars), due to their fast charging rate. Electrochemical capacitors may be divided into two main categories based on their energy storage mechanism: electric double-layer capacitors (EDLCs) and supercapacitors. EDLCs store electrical charge in a double layer at the interface between the electrode and electrolyte. On the other hand, supercapacitors are devices that yield two different capacitive behaviors: electric double-layer capacitance and super-capacitance related to a redox reaction at the interface between an electrolytic solution and electrode surface [1]. As super-capacitive materials metal oxides and conducting polymer have been extensively studied in the past decades [2]. Conducting polymers, such as polypyrrole (PPy), polyaniline (PANI) and poly(3,4-ethylenedioxythiophene) (PEDOT), combine advantages of organic polymers with electronic properties of semiconductors, and hence are attractive materials for the use in data storage media and photovoltaic cells. They also can be used as electrochromic devices, chemical sensors and biosensors, logic or switching elements and supercapacitors [3]. Furthermore, NiO-based nanostructures and thin films have been extensively used as electrode materials for lithium-ion batteries and fuel cells, electrochromic films, gas sensors, and electrochemical supercapacitors. Since NiO is cheaper than RuO2, environmentally benign, and easy to process using a variety of methods, it deserves considerable research activities toward high-performance electrochemical supercapacitor applications [3]. An important parameter characterizing supercapacitors is their active surface – a reaction that is a source of electric current and accumulation of the charge in a form of the electric double layer occurs at the electrolyte/electrode phase boundary. Excellent materials, suitable for fabrication of supercapacitors, seem to be polymeric and metal transition oxide nanowire arrays. It is reasonable to believe that one-dimensional nanostructures can reduce diffusion resistance of electrolytes in rapid charge/discharge processes. Furthermore, nanowires have high conductivity. In the search for new materials, composites play an important role. As a multicomponent system, composites combine the properties of their constituents, which make it possible to overcome the drawbacks of individual components. Therefore, the aim of this research was to synthesize and examine a material exhibiting a high capacitance. The first step of this work included the synthesis of nanostructured anodic aluminum oxide (AAO) by anodization aluminum foil in an oxalic acid solution. The second stage was devoted to the electrochemical reduction of the barrier layer at the bottom of pores. Then, DC electrodeposition of polymeric (e.g., PPy, PEDOT, PANI) nanowires directly in the pores of the AAO template was done. After the AAO template removal, the nanowire array was modified by NiO nanoparticles. The structural features of the hybrid polymeric-metal oxide nanowires were investigated by means of Field Emission Scanning Electron Microscopy (FE-SEM). The chemical composition of hybrid polymeric-NiO nanowires was evaluated by Energy-Dispersive X-ray Spectroscopy (EDAX). The surface states of the hybrid polymeric-NiO nanowire array was investigated by X-ray photoelectron spectroscopy (XPS). The hybrid polymeric-NiO nanowire arrays were examined by cyclic voltammetry, galvanostatic charge–discharge tests and electrochemical impedance spectroscopy in order to determine their capacitance values, optimal working potential range and charge propagation. The discussion will also include the cyclability tests and the capacitance retention during an accelerated ageing procedure.

Magnetic investigations of post-annealed metallic Fe nanowires via electrodeposition method

Smooth and long Fe nanowire (NW) arrays were successfully fabricated inside nano-channels of anodic aluminum oxide (AAO) template with DC electrodeposition method at room temperature. As-synthesized Fe NWs were investigated by scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) methods and X-Ray diffraction (XRD) for morphology, elemental analysis and structural information, respectively. It has been observed that embedded Fe NWs have bcc crystal structure and polycrystalline nature. Shape anisotropy played the dominant role to orient the magnetic moments along the nanowires long axes. Low squarness (Mr/Ms) values for in-plane magnetization loops demonstrate the presence of dipole interaction field between the nanowires due to high pore density or small inter-pore distance (~125nm). Annealing treatment improved the magnetic properties of Fe nanowires. The possible magnetic discussions in nano-geometry have been presented in detail.

Self-assembly of aligned CuO nanorod arrays using nanoporous anodic alumina template by electrodeposition on Si substrate for IR photodetectors

Hexagonally highly-ordered thin nanoporous anodic alumina (AAO) template of pre-deposited Al thin film onto Si substrate was fabricated under controllable conditions through a two-step anodization for the growth of nanostructured materials. The obtained AAO template has approximately 60nm of pore diameter and 1200nm length with 110nm interpore distances within an area of 0.75cm2. A bottom barrier layer of the AAO template was removed by wet etching using phosphoric acid (5wt%) for several minutes at room temperature. As an application, Cu nanorod-arrays embedded in AAO template was prepared by dc electrodeposition. The electrodeposited Cu nanorod-arrays onto Si based AAO template were oxidized at optimized conditions inside a conventional furnace to produce high-quality CuO nanorod arrays. The free-standing CuO nanorod arrays were formed after subsequent removal of AAO template. Fast with high-performance CuO nanorod-arrays IR photodetector based on MSM were fabricated with Al contact electrodes and its optoelectronic properties were examined. The electrical performance and photoelectric response performance were studied and the results showed that IR photodetector exhibited a high sensitivity to 808nm IR laser light. Both the response and recovery time were found to be fast; 0.19 and 0.17s, respectively, which are much shortest time compared to other IR photodetectors reported in the literature.

Magnetic response of hybrid ferromagnetic and antiferromagnetic core-shell nanostructures.

The synthesis of FeTiO3-Ni(Ni80Fe20) core-shell nanostructures by a two-step method (sol-gel and DC electrodeposition) has been demonstrated. XRD analysis confirms the rhombohedral crystal structure of FeTiO3(FTO) with space group R3[combining macron]. Transmission electron microscopy clearly depicts better morphology of nanostructures with shell thicknesses of ∼25 nm. Room temperature magnetic measurements showed significant enhancement of magnetic anisotropy for the permalloy (Ni80Fe20)-FTO over Ni-FTO core-shell nanostructures. Low temperature magnetic measurements of permalloy-FeTiO3 core-shell structure indicated a strong exchange bias mechanism with magnetic coercivity below the antiferromagnetic Neel temperature (TN = 59 K). The exchange bias is attributed to the alignment of magnetic moments in the antiferromagnetic material at low temperature. Our scheme opens a path towards optimum automotive systems and wireless communications wherein broader bandwidths and smaller sizes are required.

Morphological and Optical Characterization of High Density Au/PAA Nanoarrays

Hexagonal nanoarrays of Au nanorods and nanopillar were deposited on nanoporous anodic alumina (PAA) membranes utilizing dc electrodeposition. The surface morphologies and optical properties were characterized by using field emission-scanning electron microscopy (FE-SEM) and UV-Vis spectrophotometer, respectively. The optical reflectance spectra of the as-prepared, pore widened, and 2D-Au nanorods-coated PAA membranes were studied in detail. The effects of the angle of incident, pore widening time, and electrodeposition time on the characteristic peaks positions and intensities of the fabricated nanoarrays were addressed. As the angle of incident increased, the interference peaks and transverse surface resonance are shifted to longer wavelengths, but the longitudinal surface plasmon resonance is shifted to shorter wavelengths. Also, the reflected intensities are decreased linearly for the as-prepared sample and decreased exponentially for Au/PAA samples. Using the modified Kubelka-Munk radiative transfer model, the energy gap is increased from 2.83 to 3.06 eV and the refractive index is decreased from 1.84 to 1.36 for the as-prepared and 70 min pore widened PAA membranes, respectively. Based on the advantages of the fabrication approach and the enhanced and controlled properties, this generation of Au/PAA arrays can be used as efficient building blocks for nanoelectronics and nanophotonic devices.

High Responsivity IR Photodetector Based on CuO Nanorod Arrays/AAO Assembly

Fast with high-performance CuO nanorod arrays IR photodetector was fabricated using CuO nanorod arrays/AAO assembly. The IR photodetector based on MSM with Al contact electrodes and its optoelectronic properties were examined. The CuO nanorod arrays used in the experiment were synthesized by DC electrodeposition method into Si-based/AAO template. The electrical performance and photoelectric response performance were studied, and the results showed that IR photodetector exhibited a high sensitivity to 808nm infrared diode laser source. Both the response and recovery time were found to be fast; 0.19 and 0.15 s, respectively, which are shorter time compared to other IR photodetectors reported in the literature.

Preparation of Zn-ZrO&lt;sub&gt;2&lt;/sub&gt; Nanocomposite Coating by DC and Pulsed Current Electrodeposition Technique with Low Current Density

In the present work, Zn-ZrO2nanocomposite coatings were deposited on the copper substrate through DC and pulse electrodeposition technique with low current density (10 mA/cm2). The effect addition of ZrO2nanoparticles and pulse current were studied. The surface morphology, microhardness and erosion resistance of Zn-ZrO2nanocomposite coating were evaluated. The result shows that, with the addition of ZrO2particles, the surface morphology of Zn-ZrO2nanocomposite coating was smoother. Phase identification by XRD confirm that Zn layer had been sucessfully deposited. The presence of ZrO2nanoparticles was not detected. Compared to DC, pulsed current electrodeposition technique showed higher cathodic efficiency, better microhardness and good erosion resistance.

Ni–W/ZrO2 nanocomposites obtained by ultrasonic DC electrodeposition

Abstract Composite coatings consisting of a nanocrystalline Ni–W alloy matrix reinforced with ZrO 2 particles (average size of 50 nm) were synthesized by electrochemical deposition assisted by an external ultrasonic field. The Ni–W/ZrO 2 coatings were deposited from aqueous sulphate–citrate electrolytes containing zirconia nanopowder in suspension on steel substrates in a system with a rotating disk electrode (RDE). The influence of relevant processing parameters (i.e., concentration of zirconia powder in plating bath, current density, hydrodynamic conditions, ultrasonic field frequency) on the composite characteristics was discussed. Based on micromechanical (microhardness, Young’s modulus) and microstructural (morphology, phase composition, crystallite size) properties of the coatings, the conditions for electrodeposition of crack-free, homogeneous Ni–W/ZrO 2 nanocomposites with enhanced functional properties have been developed.