Effect Of Deposition Potential Research Articles

Electrochemical synthesis of three-dimensional porous networks of nickel with different micro-nano structures for the fabrication of Ni/MnOx nanocomposites with enhanced supercapacitive performance

We have electrochemically synthesized 3D-porous Ni/MnOx nanocomposites for supercapacitor applications. 3D porous micro-nanostructured networks of nickel were prepared using hydrogen bubbles as a dynamic template at different deposition potentials and times. The prepared nickel films were used then as 3D-porous substrates for anodic deposition of manganese oxide nanostructures. The effects of deposition potential and time on the structure of the prepared nickel scaffolds and especially on the capacitive behavior of the subsequently fabricated 3D-porous Ni/MnOx nanocomposites were investigated. The results show that the areal capacitance and especially the rate capability of prepared Ni/MnOx nanocomposites have improved with increasing the deposition potential or optimizing the deposition time of nickel films in the nanocomposites. The prepared 3D-porous Ni/MnOx nanocomposite, in which the nickel scaffold has been deposited at the potential of −6V and duration of 90s, show almost the highest capacitive performance among all other prepared nanocomposites. This prepared nanocomposite, with the loading mass of 1.65mgcm−2, showed the high areal capacitance of 654mFcm−2 (396.4Fg−1) at the current density of 0.5mAcm−2 (0.3Ag−1) in 0.5M Na2SO4 solution. This nanocomposite also revealed the highest rate capability; the capacitance retention is about 63% (412mFcm−2) with increasing the discharge rate from 0.5 to 20mAcm−2, which is almost twice the observed amount of retention when the deposition potential of Ni films was −2V (31%) or their deposition time was 45s (34%). In addition, the prepared nanocomposite exhibited an outstanding cycling stability. The capacitance retention was about 98.91% after performing 2000 charge-discharge cycles.

A glassy carbon electrode modified with graphene oxide decorated silver phosphate nanodentrites for amperometric determination of dissolved hydrazine

The authors describe an electrochemical approach for the preparation of a glassy carbon electrode (GCE) modified with graphene oxide and silver nanodentrites (AgNDs). The coating was obtained by using an aqueous solution containing silver nitrate, phosphate and ammonia. The phosphate anions act as a scaffold for the improved deposition of AgNDs. The effects of deposition potential and time and concentration of electrolyte on the formation of the AgNDs were optimized. The modified GCE displays good electrocatalytic activity towards the oxidation of dissolved hydrazine. The electron transfer coefficient and diffusion coefficient are 0.60 and 4.64 × 10−5 cm2 s−1 respectively. The electrode exhibits a linear response over the 100 nM to 670 μM hydrazine concentration range and a detection limit (LOD) of 33 nM. The sensitivity of the modified electrode is 2077 μA mM−1 cm−2 at a typical working voltage of 0.1 V (vs Ag/AgCl). This LOD is much lower than that of the allowable concentration of hydrazine in drinking water as defined by the US EPA and the WHO.

Effect of Deposition Potential on the Structure, Electrocatalytic Activity and Stability of Pt Films for Methanol Oxidation

Effect of Deposition Potential on the Structure, Electrocatalytic Activity and Stability of Pt Films for Methanol Oxidation

Synthesis of Ni-Fe thin films by electrochemical deposition technique and characterization of their microstructures and surface morphologies

Microstructural features and surface morphologies of Ni-Fe thin films fabricated by the electrochemical deposition technique have been experimentally studied. Ni-Fe thin films have been deposited under different deposition potentials and FeSO$_{4}$ concentrations. Energy dispersive X-ray measurements demonstrate that the Fe content decreases (increases) as the deposition potential (FeSO$_{4}$ concentration) is enhanced. All of the produced films exhibit an anomalous codeposition behavior. The effects of deposition potential and FeSO$_{4}$ concentrations on the degree of anomalous codeposition have been also characterized. X-ray diffraction studies reveal that the films have face-centered cubic crystallographic structures with [111] preferred crystallographic orientation regardless of the applied deposition conditions. However, the crystallization and the crystallite size of the films are affected by changing of the FeSO$_{4}$ concentration and the deposition potential. The results of scanning electron microscopy analyses verify that the surface structure of the film electroplated from the electrolyte with higher FeSO$_{4}$ concentration under higher deposition potential exhibits a more homogeneous and dense structure with smaller grain sizes.

Appropriate deposition parameters for formation of fcc Co–Ni alloy nanowires during electrochemical deposition process

The effect of deposition potential on the crystal structure and composition of Co–Ni alloy nanowires is studied by XRD, FE-SEM and EDX. The alloy nanowires deposited at −3.2 V are metastable fcc phase Co–Ni. The alloy nanowires deposited at −1.8 V are hcp phase Co–Ni. The formation of the metastable fcc alloy nanowires can be attributed to smaller critical clusters formed at the high potential as the smaller critical clusters favor fcc structure because of the significant surface energy effect. The content of Co inside nanowires increases with increasing potential. This can be understood by the polarization curves of depositing Co and Ni nanowires, which show that the current density ratio of Ni to Co at low potential has larger value than that at high potential.

Electrodeposition of flake-like Cu2O on vertically aligned two-dimensional TiO2 nanosheet array films for enhanced photoelectrochemical properties

A novel Cu2O/TNS composite structure of single crystal TiO2 nanosheet (TNS) arrays decorated with flake-like Cu2O were synthesized by a facile hydrothermal reaction followed by the electrodeposition process. The effects of deposition potential on the microstructure, morphology, and optical property of the thin films were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV–vis spectrophotometer. When the deposition potential is higher than −0.4V, peaks corresponding to Cu appear, meanwhile, flake-like Cu2O become agglomerating, and transform into dense Cu2O particles. Additionally, photoelectrochemical experiments indicate that the films deposited at −0.4V show the lowest resistivity and highest exciton separation efficiency. This enhanced photoelectrochemical properties can be explained by synergistic effect of p-type flake-like Cu2O and n-type TiO2 heterojunctions combined with two-dimensional TiO2 nanosheet with exposed highly reactive {001} facets.

Evaluation of Bismuth Modified Carbon Thread Electrode for Simultaneous and Highly Sensitive Cd (II) and Pb (II) Determination

AbstractBismuth film modified and chemically activated carbon micro‐thread electrodes were investigated for the simultaneous determination of Cd(II) and Pb(II) using square wave anodic stripping voltammetry. The carbon thread electrode was characterised using both surface and electrochemical techniques. Electrochemical impedance spectroscopy (EIS) studies demonstrated that the H2SO4/IPA‐treated carbon thread electrode showed a much improved resistance response (Rct=23 Ω) compared to the IPA‐untreated carbon thread (Rct=8317 Ω). Furthermore, parameters such as the effect of deposition potential, deposition time and Bi(III) concentration were explored using square wave voltammetry. Detection limits (S/N=3) for Cd(II) and Pb(II) were found to be 1.08 µg L−1 and 0.87 µg L−1, respectively and response was found to be linear over the range 5–110 µg L−1. The proposed Bi/IPA‐treated carbon thread electrode exhibited a high selectivity towards Cd(II) and Pb(II) even in the presence of a range of heavy metals and is capable of repetitive and reproducible measurements, being attributed to the high surface area, geometry and electrode treatment characteristics. The proposed metal ion sensor was employed to determine cadmium and lead in river water samples and % RSD was found to be 5.46 % and 5.93 % for Cd(II) and Pb(II) respectively (n=3). Such facile sensing components favour the development of cost effective portable devices for environmental sample analysis and electrochemical applications.

Deposition Potential Influence on the Electrodeposition of Zn–Ni–Mn Alloy

The effect of deposition potential on the electrodeposition, composition, surface characteristics and corrosion resistance properties of Zn–Ni–Mn alloy coatings were investigated. During the deposition potential range from −0.500 to −1.000 V, normal codeposition of the alloy components occurred, meanwhile at deposition potentials more cathodic than −1.000 V, the anomalous codeposition took place. Shifting the deposition potentials toward the negative direction led to an increase in the thickness of the deposit, incremented the adhesion and compactness and improved the corrosion resistance properties. X-ray diffraction studies of the deposit showed the presence of hexagonal pure Zn phase, hexagonal Mn0.27Zn0.73 phase and cubic γ-Ni5Zn21 and/or tetragonal δ-Ni3Zn22 phases.

A glassy carbon electrode modified with bismuth oxide nanoparticles and chitosan as a sensor for Pb(II) and Cd(II)

A glassy carbon electrode (GCE) modified with bismuth oxide nanoparticles (BiONPs) and the chitosan (CS) was fabricated, and used to simultaneously determine lead and cadmium by differential pulse anodic stripping voltammetry. This modified electrode can be self-designed and prepared at low-costs. Scanning electron microscopy image shows that the mean diameter of BiONPs is about 235 nm. The sensitivity of the BiONPs-CS-GCE is much better than that of the bare GCE and the CS-GCE. The effects of deposition potential, pH of the solution, and deposition time were optimized. Under the optimized conditions (pHABS = 5.0, Edep = −1.7 V, tdep = 180 s), the composite film electrode was then applied to the analysis of lead (II) and cadmium (II). The linear range of the electrode was 0.4–2.8 μM for Pb (II) and 0.8–5.6 μM for Cd (II), with a limit of detection of 0.15 μM for Pb (II) and 0.05 μM for Cd (II), respectively. The determination of Pb (II) and Cd (II) in spiked tap water was performed and gave recoveries ranging from 99 to 122 % for Pb (II), and from 96 to 120 % for Cd (II).

Effects of Deposition Potentials on the Morphology and Structure of Iron-Based Films on Carbon Steel Substrate in an Alkaline Solution

The purpose of this work is to investigate the effect of electrochemical deposition potential on the morphology and structure of iron-based films on the carbon steel in an alkaline Fe(III)-triethanolamine solution. The deposition potentials were controlled in the range from −1.05 to −1.23 VSCEfor 1800 s at 80°C. Total amount of electric charge for electrodeposition process was increased with increasing deposition potential in negative direction. Pure magnetite films with a columnar and defect-free structure were deposited in the potential range from −1.05 VSCEto −1.11 VSCE. However, petal-like magnetite film containing ferrihydrite and iron was formed at −1.17 VSCE. At more negative potential of −1.23 VSCE, two distinct layers were observed: a porous outer layer containing ferrihydrite and goethite and a compact inner layer consisting of columnar metallic iron. In the potential range from −1.05 to −1.11 VSCE, the pure magnetite films gradually increased the thickness and decreased the surface roughness with an increase of the overpotential. The magnetite film deposited at −1.11 VSCEshowed the most thick layer and smooth surface state.

Low Cost Hydrogen Peroxide Sensor from Manganese Oxides Modified Pencil Graphite Electrode

Electrodeposition of manganese oxides film onto the cheap pencil graphite electrode using potassium permanganate precursor provides the good alternative method of fabrication the low cost hydrogen peroxide sensor. Effect of deposition potential, deposition time and concentration of potassium permanganate were investigated. The modified electrode displayed electrocatalytic activity towards the oxidation of hydrogen peroxide in alkaline medium. Amperometric detection of hydrogen peroxide in ammonium buffer pH 9.0 is possible at the operation potential of +0.50V vs Ag/AgCl instead of over +0.80V vs Ag/AgCl with unmodified electrode. Linear concentration range between 0.50-138ppm of hydrogen peroxide was obtained with a detection limit of 0.28ppm.

Surface modification, strengthening effect and electrochemical comparative study of Zn-Al2O3-CeO3 and Zn-TiO2-CeO3 coating on mild steel

Surface enhancement of engineering materials is necessary for preventing service failure and corrosion attacks industrially. The surface modification, strengthening effect and electrochemical comparative study of Zn-Al2O3-CeO3 and Zn-TiO2-CeO3 coating on mild steel was investigated. Deposition was performed to obtain a better surface adherent coating using the electrodeposition technique. Co-deposition of mild steel resulted into surface modification attributes to the complex alloys that were developed. Films of mild steel were electrodeposited on zinc electrodes using the chloride bath solutions. The effect of deposition potentials was systematically studied using a focus ion beam scanning electron microscope (FIB-SEM) and an atomic force microscope (AFM) to observe the surface morphology, topography and the surface adherent properties of the coatings. The elemental composition and the phases evolved in composite coatings were measured by means of the energy dispersed spectrometer (EDS). The microhardness measurements and corrosion behaviours of the deposits were investigated. Weight loss measurement was conducted on the plated samples to observe the rate of corrosion and it was observed that there was severe corrosion on the controlled sample in comparison to the plated samples and that Zn-TiO2-CeO3 resisted more corrosion attacks.

Potentiostatically synthesized flexible polypyrrole/multi-wall carbon nanotube/cotton fabric electrodes for supercapacitors

A polypyrrole (PPy)/multi-walled carbon nanotube (MWCNT)/cotton flexible electrode for high-performance supercapacitors was fabricated by a facile two-step method, including MWCNT-coated cotton prepared by a facile “dip and dry” method and then subjected to the electro-deposition of PPy by a potentiostatic deposition technique. The effects of deposition potential, time, and molar ratio of p-toluenesulfonic acid to pyrrole (Py) on the properties of textile electrodes were studied. The sheet resistances and surface morphologies of the as-prepared composite fabrics obtained under different conditions were investigated by means of a four-point probe method and field-emission scanning electron microscope and the electrochemical performances of the PPy/MWCNT/cotton electrodes were evaluated by cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance spectroscopy measurements. These composite fabrics exhibited outstanding flexibility, high conductivity, with sheet resistance of 6.0 ± 0.4 Ω sq−1, a cauliflower structure with small holes on the surface favoring the contact between the electrode active material, a specific capacitance of 535 F g−1 (maintaining 97.8 % after 100 cycles), and a fitting value of charge-transfer resistance of 13.9 Ω cm−2, which offers great promise in wearable energy storage device applications because of their low-cost and high-performance features.

Microstructure, morphology and sunlight response of cuprous oxide thin films

Cuprous oxide thin films were successfully synthesized on FTO substrates via the electrochemical method by changing the deposition potential. The effects of deposition potential on the microstructure, morphology, optical band gap and photoresponse of the thin films were investigated. The results revealed that intensity of (111) diffraction peak and preferential orientation along (111) plane increase with increasing the absolute value of deposition potential. The thin film with the more negative deposition potential has an increased average particle size and compact degree. The optical band gap of the sample deposited at −0.5 eV presents the largest value of 1.82 eV. Upon sunlight illumination, the photocurrent of thin film rises quickly at first and then gets slower. The slow photoresponse may be attributed to the capture of carriers by deep level traps in our case.

Preparation of Co2FeSn Heusler alloys by electrodeposition method

We propose a new method for preparing Heusler alloys on the basis of the electrodeposition. The alloy composition is controllable by the deposition potential. The composition ratio of (Co, Fe) and Sn is inversely proportional to the deposition potential. The effect of deposition potential on alloy composition, surface morphology, crystal structure, and magnetic properties of the samples was investigated. The (Co, Fe) vs. Sn alloy composition displayed an inverse dependence on the deposition potential. According to the magnetic measurement, the obtained Co2FeSn composition alloy showed ferromagnetic properties. The coercivity shows the minimum value in the stoichiometric samples.

Electrodeposition of ZnSe thin film and its photocatalytic properties

ZnSe is an important and excellent II–VI semiconductor material, which has the direct transition band structure. In this paper, ZnSe thin films were prepared by electrochemical deposition method, and the effects of deposition potential and deposition time on the photocatalytic properties of the ZnSe thin films were studied systematically. The results showed that more positive potential and longer deposition time lead to the decrease of degradation efficiency. The deposition time has a significant effect on the degradation efficiency. The film which was prepared at the potential of −1V (versus Pt) for 1h showed the highest degradation efficiency, and methyl orange could be completely degraded within 5h. The mechanisms for the photocatalytic activities were also discussed.

Nucleation and growth mechanism of Co–Pt alloy nanowires electrodeposited within alumina template

Co–Pt alloy nanowires were electrodeposited by direct current electrodeposition within nanoporous alumina templates with varying deposition potentials. The effect of deposition potential on nucleation and growth mechanisms during electrodeposition of Co–Pt alloy nanowires was investigated. The less negative deposition potential (−0.9 V) favours the instantaneous nucleation mechanism. The positive deviation from theoretical instantaneous and progressive nucleation mechanisms occurs at higher negative deposition potentials. The hysteresis behaviour and magnetic properties of electrodeposited Co–Pt alloy nanowires altered with varying deposition potential. The easy magnetization direction was in direction perpendicular to the wire axis. The deposition potential dependent change in hysteresis behaviour with increased coercivity and scattered remanence ratio was observed. This is attributed to better crystallinity with reduced defect density and hydrogen evolution causing structural changes at more negative deposition potentials.

Protective properties of cataphoretic epoxy coating on aluminium alloy AA6060 modified with electrodeposited Ce-based coatings: Effect of post-treatment

Abstract Ce-based conversion coatings (CeCCs) are a promising alternative to toxic chromate coatings on the metal substrates. In this work the CeCCs were electrodeposited on aluminium alloy AA6060 from aqueous solution of Ce(NO3)3 at different potentials (−0.95 V, −1.2 V and −1.4 V). Effect of deposition potential and post-treatment in the phosphate solution on morphology and protective properties of CeCCs with top cataphoretic epoxy coating was studied. To assess the differences between the protective systems, originating from the different CeCCs pre-treatments, electrochemical impedance spectroscopy (EIS), polarization measurements, AFM and SEM/EDS analysis were used. The EIS study was undertaken to follow the evolution of corrosion behaviour of epoxy coating/CeCCs protective systems over prolonged time of exposure to the chloride environment (3 wt.% NaCl). Results suggest significantly improved corrosion stability of epoxy coating on AA6060 with as-deposited CeCCs sub-layers with respect to the same epoxy coatings with phosphate post-treated CeCCs. The far best protective properties, i.e., the greatest value of pore resistance and the lowest value of corrosion current density were provided by the epoxy coating/CeCC protective system with CeCC deposited at −1.2 V and without post-treatment.

Effect of deposition potential on the properties of Cu2ZnSnS4 films for solar cell applications

Cu2ZnSnS4 (CZTS) films have been successfully deposited on Mo-coated glass substrates by the rapid thermal processing sulfurization of co-electroplated CZTS precursors. Effects of single-deposition potential and double-deposition potential on the properties of CZTS films and CZTS solar cells were investigated. The CZTS films deposited by double-deposition potential show a relatively flat surface and sufficient sulfurization, reduce considerably the thickness of MoS2 interfacial layer and thereby improve the device efficiency greatly by the boost of Jsc and Voc compared with those deposited by single-deposition potential. The solar cell fabricated with the CZTS absorber deposited by double-deposition potential achieves a conversion efficiency of >3.06%.

Corrosion study of ceria coatings on AA6060 aluminum alloy obtained by cathodic electrodeposition: Effect of deposition potential

Among potential replacements for chromates, cerium-based conversion coatings (CeCCs) have been identified as leading candidates, showing a good promise as environmentally compliant corrosion inhibitors on Al alloys. In this work, CeCCs were synthesized on AA6060 by electrolytic deposition (ELD), a well-suited method for the fabrication of films with controllable properties, at low processing temperature and cost. The CeCCs were deposited at room temperature from Ce(NO3)3 solution, applying different cathodic potentials (−1.1, −1.4 and −1.6V vs. SCE) for different deposition times between 5 and 20min. Structural, morphological and compositional properties of the films were characterized by X-ray diffraction, Raman spectroscopy and scanning electron microscopy coupled with energy dispersive spectroscopy. Ceria films were nanostructured, exhibiting a cubic fluorite structure. From corrosion perspective, the quality of CeCCs was evaluated in 0.5M NaCl solution via electrochemical impedance spectroscopy and linear sweep voltammetry. As shown, the coating corrosion quality is the interplay between deposition potential and deposition time. The highest potential led to highly cracked films of poor adherence, even at the shortest deposition time, which disqualified them from any corrosion protection application. The lowest potential (−1.1V) produced crack-free coatings, but longer times (≥10min) were needed to provide the protective layer formation. The best corrosion protection offered CeCCs prepared at −1.4V. The highest Rp (58.2kΩcm2) and the smallest CPE (12.6·10−6snΩ−1cm) were obtained at 20min deposition time. However, from economical point of view, 10min deposition is a promising choice. These CeCCs also improved pitting corrosion resistance owing to homogeneous microstructure and sufficient thickness.