Cathodic Electrodeposition Process Research Articles

Electrodeposited coral-like bimetallic NiCo-MOFs on Ni foam as binder-free electrodes for high performance all solid-state asymmetric supercapacitors

The rational design of electrode materials is greatly significant for improving the performance of the supercapacitor. In this work, high mass loading coral-like bimetallic nickel/cobalt-based metal-organic frameworks are in-situ constructed on cobalt-modified nickel foam (NiCo-MOFs/NF) via a facile cathodic electrodeposition process as binder-free electrodes for supercapacitors. Such electrodes with optimized Ni/Co molar ratios, high specific surface area and unique hierarchical structure with open channels provide abundant reaction active sites and fast ion transfer kinetics, and the three-dimensional porous Ni foam (NF) offers successive pathways for fast electron transportation. As a result, an ultrahigh areal specific capacitance of over 9300 mF cm−2 with a high-capacity retention of over 87% is achieved at 10 mA cm−2. And the NiCo-MOFs/NF with Ni/Co molar ratio of 1:3 presents a favorable stability of retaining its 73% original specific capacitance after a long-term cycling of 10,000 cycles. Moreover, the assembled all solid-state asymmetric supercapacitors (ASSCs) device performs an energy density of 617.2 mWh cm−2 at a power density of 7506.9 mW cm−2.

Fe2O3/NiO photocathode for photocatalytic methanol fuel cell: An insight on solar energy conversion

A promising photocathode material based on Fe2O3/NiO heterostructure was developed for efficient photoelectric conversion in a methanol fuel cell. The Fe2O3/NiO heterogeneous film was prepared via in-situ hydrothermal synthesis and then cathodic electrodeposition process. Surface photovoltage results showed that after electrodeposition of NiO on the Fe2O3 film, the separation direction of photogenerated electrons and holes was reversed. The photogenerated electrons accumulated on the surface of Fe2O3/NiO photocathode can induce the oxygen reduce reaction due to the relatively high conduction band level of the entire semiconductor composite. In addition, the Fe2O3/NiO based photocatalytic methanol fuel cell showed significant improvements under illumination of simulated sunlight, and the short-circuit current and open-circuit voltage reach 183 μA/cm2 and 0.48 V respectively. The work provided a new vision for solar - chemical energy conversion in the fuel cell.

Investigating the large potential window of NiCo2O4 supercapacitors in neutral aqueous electrolyte

The enhancement of potential window can be identified as one of the effective pathways to boost the energy density of supercapacitors to break the limitation of practical applications. NiCo2O4 nanosheet networks grown on carbon cloth are prepared via a facile cathodic electrodeposition process with a post-annealing procedure. A neutral electrolyte of mixing 2 M LiSO4 and 0.1 M CoSO4 is employed to enlarge the potential window of the as-prepared NiCo2O4/CC electrode to 0–1.2 V (vs SCE), while the corresponding potential window in alkaline electrolyte is merely 0–0.5 V. Moreover, the NiCo2O4/CC electrode shows an excellent cycling stability of maintaining 129.7% after 10,000 cycles in neutral electrolyte. The quantitative CV kinetic analysis is carried out to explore the charge storage mechanism, manifesting that capacitive contribution is estimated as high as 64.7–81.8% at the sweep rate of 3–10 mV s−1. Results demonstrate that this neutral electrolyte can greatly boost the electrochemical characteristics of the NiCo2O4 electrode and also provide the possibility of achieving better characteristics in the field of energy storage when applied in other battery-type materials.

A new green, energy-saving, and pressing refining process for the recovery of ultrahigh-purity lead in alkaline solution from spent lead plate grids

This paper reports a novel green and energy-saving method to prepare ultrahigh-purity lead from spent lead plate grids via a pressing-electrorefining process. The lead plate grids from spent lead-acid batteries were firstly pressed into high-density crude lead plates, then the crude lead plates were electro-refined in a NaOH–NaHPbO2 solution plus additive of JZ04 to recover an ultrahigh-purity lead. This paper systematically studied the effects of electrolyte temperature, the concentration of NaOH and Pb2+, additives, and current density on the anodic stripping process, cathodic electrodeposition process, and electrorefining process via constant current electrolysis, AC impedance, and LSV methods. The lead plate grids, anodic stripping product, and cathodic electrodeposited lead were examined by field emission scanning electron microscope, EDS, XPS, and ICP analytical methods. Results show that under the optimum conditions, the energy consumption of electrodeposition is only 18 kW·h·(t Pb)−1 with the recovery efficiency of 99.7%; the purity of obtained lead reaches 99.9991%, much higher than the criteria of the European (EN 12659-1999, 99.99%) and the Chinese standard (GB/T 469-2013, 99.994%).

Mechanism of Initial Film Formation during Cathodic Electrodeposition of Coatings

Electrodeposition of coatings is an effective way to form a protective layer on metal surfaces of complex shape. The uniformity of the deposit is a function of the current distribution, and depends on the induction time (time prior to “initiation” of deposition), the local deposition rate and the resistivity of the film that is formed. In cathodic electrodeposition, hydrogen gas evolves on the deposition surface, leading to an increase in the local pH. The change in pH reduces the solubility of the positively charged resin-containing micelles and causes a coating to form on the surface. The induction time, which is a key factor in the prediction of film thickness, has been attributed to the time that is required to increase the local pH to about 12 [1, 2]. The deposition rate, which is initially low, changes significantly during the induction period and eventually increases to a steady value that is proportional to the charge passed. An increased fundamental understanding is needed to improve our ability to accurately model E-coat systems in order to optimize performance. The purpose of this study is to develop a detailed understanding of the initial stages of deposit growth. Of particular interest are the changes that take place during the induction time. Experiments designed to elucidate the role of pH change clearly show that the local change in pH alone is not responsible for the induction time. This observation was further supported by additional experiments where the induction time at a specified current was observed to vary with the type of substrate used for deposition. Consequently, scanning electron microscopy was used to study the morphology of the initial deposit on different substrate surfaces including bare steel, galvanized steel, and phosphated steel. It was found that the initial film tends to form preferentially on defects and scratches in the metals. This observation was validated by experiments with intentionally scratched surfaces. The initial film also appeared to form around gas bubbles that were present on the substrate surface. The mechanism for preferred deposition at defects and bubbles is currently under investigation. As part of this effort, deposition on “defect free” surfaces has been performed. Microscopic images are used to track deposit formation as a function of time during the initial stages of deposition before formation of a highly resistive film. The rate of deposition increases with time, which may be connected to an increase in the local current density in the deposit free areas. The additional insight provided by this study will provide the basis for an improved model of the early stages of E-coat deposition. This model will then be incorporated into a large-scale simulation tool to enable improved process prediction and optimization. Acknowledgment The authors gratefully acknowledge funding from the Ford Motor Company under their University Research Program (URP). References Miskovic-Stankovic, V.B. and M.D. Maksimovic, The effect of concentration on the cathodic electrodeposition process. Process in Organic Coating, 1988. 16: p. 255-263.Pierce, P.E., The physical chemistry of the cathodic electrodeposition process. Journal of Coatings Technology and Research, 1981. 53: p. 52.

Mg(OH)2/Graphene Nanocomposites Prepared by Cathodic Electrodeposition for the Adsorption of Congo Red

A facile cathodic electrodeposition process was developed to prepare Mg(OH)2/Graphene nanocomposites (MGN), which was used to remove Congo Red (CR), an anionic dye from aqueous solution. The morphology and phase structure were analyzed by transmission electron microscopy (TEM), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), Raman and X-ray photoelectron spectroscopy (XPS). The effects of experimental parameters, such as graphene content, adsorption time, initial concentrations of CR and pH values, on the adsorption capacity of CR were studied. The obtained MGN shows the good performance in CR, with an adsorption capacity of 1986.43[Formula: see text]mg[Formula: see text]g[Formula: see text]. The equilibrium adsorption and kinetics data fit with Langmuir isotherm and the pseudo-second-order model, respectively. Thermodynamic data suggest that CR adsorption onto MGN is spontaneous ([Formula: see text]: –9.62[Formula: see text]kJ[Formula: see text]mol[Formula: see text] at 313[Formula: see text]K, endothermic ([Formula: see text]: 36.261[Formula: see text]kJ[Formula: see text]mol[Formula: see text] and the degree of disorder increased ([Formula: see text]: 146.848[Formula: see text]J[Formula: see text]moL[Formula: see text][Formula: see text]K[Formula: see text] at the solid-solution interface. Moreover, the adsorption activation energy ([Formula: see text]: 38.929[Formula: see text]kJ[Formula: see text]mol[Formula: see text] of CR evaluated from the Arrhenius equation illustrates that it is a physical process. This adsorbent exhibits efficient adsorption properties and high recycling efficiency, making it a promising adsorbent for removing anionic dyes.

Surface area control of nanocomposites Mg(OH)2/graphene using a cathodic electrodeposition process: high adsorption capability of methyl orange

The nanocomposites Mg(OH)2/graphene (nano-MG) were controllably prepared by a facile cathodic electrodeposition.

Effect of electrodeposition modes on surface characteristics and corrosion properties of fluorine-doped hydroxyapatite coatings on Mg–Zn–Ca alloy

The microstructure, morphology and composition highly determine the corrosion resistance and bioactivity of coating. In traditional cathodic electrodeposition process, because of the unfavorable effects of the polarization of concentration difference and H 2 evolution, fluorine-doped hydroxyapatite coating was loose and porous. This coating could not ensure the long-term stability of the Mg alloy implants. In order to improve the corrosion resistance and bioactivity of coating, pulse electrodeposition and H 2O 2 were introduced into the electrodeposition to deposit fluorine-doped hydroxyapatite coating. As a comparative study, microstructure, corrosion resistance properties and bioactivity of traditional cathodic electrodeposition coating and pulse electrodeposition coating were investigated, respectively. The results revealed that nano fluorine-doped hydroxyapatite coating could be prepared by pulse electrodeposition, and the coating was dense and uniform. The potentiodynamic polarization experiment indicated that the dense and uniform coating could effectively protect Mg alloy substrate from corrosion. Immersion testing was performed in simulated body fluid. It was found that pulse electrodeposition coating could more effectively induce the precipitation of Mg 2+, Ca 2+ and PO 4 3− in comparison with traditional cathodic electrodeposition coating, because the nano phase had comparatively high specific surface area. Thus magnesium alloy coated with fluorine-doped nano-hydroxyapatite coating may be a promising candidate as biodegradable bone implants, and was worthwhile to further investigate the in vivo degradation behavior.

ZnO microsheet modified TiO2 nanoparticle composite films for dye-sensitized solar cells

Randomly oriented ZnO microsheets were successfully self-assembled on TiO2 nanoparticle (TN) film to act as the scattering layer via a cathodic electrodeposition process. The light scattering properties of ZnO microsheets were studied by UV-Vis spectrometer in the 400–800 nm wavelength range. It was found that ZnO microsheets exhibited excellent ability to scatter the incident light for ZnO microsheet-TiO2 nanoparticle (ZT) composite films. The results showed that dye-sensitized solar cells (DSSCs) fabricated with ZT composite films showed higher short-circuit density (Jsc) and conversion efficiency than TN-based DSSCs, due to the light scattering properties of ZnO microsheets.

Preparation of Bi 2S 3 thin films with a nanoleaf structure by electrodeposition method

Nanoleaf-like Bi 2S 3 thin films were deposited on indium tin oxide (ITO) glass using Bi(NO 3) 3 and Na 2S 2O 3 as precursors by a cathodic electrodeposition process. The as-deposited thin films were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and photoluminescence spectrum (PL). The influence of precursor solution mole concentration ratios [Bi(NO 3) 3]/[Na 2S 2O 3] on the phase compositions, morphologies and photoluminescence properties of the obtained thin films were investigated. Results show that a uniform Bi 2S 3 thin film with nanoleaf structure can be obtained with the precursor solution concentration ratio [Bi(NO 3) 3]/[Na 2S 2O 3] = 1:7. The as-prepared thin films exhibit blue-green photoluminescence properties under ultraviolet light excitation. With the increase of concentration ratios [Bi(NO 3) 3]/[Na 2S 2O 3] in the deposition solution, the crystallizations and PL properties of Bi 2S 3 thin films are obviously improved.

STUDY OF THE STOICHIOMETRIC RATIO OF ONE-STEP ELECTRODEPOSITED CuInSe2 FILMS ON ITO/SODA-LIME GLASS

Copper indium diselenide ( CuInSe 2) thin films were grown on indium–tin oxide (ITO)/soda-lime glass using a one-step cathodic electrodeposition process at potentials lower than -0.6 V vs SCE, and in the presence of a large excess of In 3+. The source solution contained CuCl 2, InCl 3, and H 2 SeO 3 complexed by citric acid. The concentration of InCl 3 in the electrochemical bath affected the structure, composition, stoichiometric ratio, and morphological properties of electrodeposited films. CuInSe 2 films with a chalcopyrite structure and quite good stoichiometry were directly electrodeposited from a solution of 20 mM InCl 3, 5 mM CuCl 2, and 8 mM H 2 SeO 3. Annealing of these CuInSe 2 films in the temperature range from 300°C to 500°C improves their crystallinity and increases their grain size. Good chalcopyrite CuInSe 2 films with a (112) preferential orientation suitable for the production of efficient solar cells are obtained after annealing at 500°C. The formation mechanism of the ternary CuInSe 2 compound during the electrodeposition process was discussed.

Highly textural lamellar mesostructured magnesium hydroxide via a cathodic electrodeposition process

Highly textural lamellar mesostructured Mg(OH) 2 thin films were obtained through one-step cathodic reduction of magnesium nitrate bath without any surfactant template at room temperature. Its microstructure, stability and morphology were investigated using XRD, TEM, FT-IR, thermal analysis and SEM technique respectively. The results indicate that the porous hydroxide/oxide materials have highly textural lamellar structures with layer spacing around 3.4 nm. The possible formation mechanism has been discussed.

Characteristics and deposition behavior of epoxy–amine adducts in cathodic electrodeposition as a function of the degree of neutralization

The characteristics and behavior of adducts prepared by the reaction of an epoxy resin with a di-functional amine in a cathodic electrodeposition process as a function of the degree of neutralization (DN) has been studied. The study revealed that the DN has a pronounced effect on the film formation behavior of the above-mentioned adduct. The observed behavior has been explained in terms of the effect of DN on the characteristic time of the electrocoagulation phenomena as well as the characteristic time of the hydrogen gas evolution in the vicinity of the cathode.

An Electrochemical Method for CuO Thin Film Deposition from Aqueous Solution

An electrochemical procedure is described for the anodic deposition of CuO thin films from solution precursors at 25-30°C in an alkaline medium (pH > 13). The deposition bath was similar to Fehling's solution using tartrate ions as a complexing agent for Cu(II). Cupric oxide deposited onto a platinum substrate at an anodic current density of 5 mA cm - 2 has a preferred orientation of [010]. Rietveld refinement of the powder diffraction pattern reveals pure Cu(II) oxide with no trace of other copper oxides. The suggested mechanism involves the irreversible electrochemical oxidation of the tartrate ligand of the Cu(II) complex leading to the CuO precipitation. The same bath can also be used to deposit Cu 2 O films using a cathodic electrodeposition process. In this case, cuprous oxide deposited onto a platinum electrode has a [111] preferred orientation.

The mechanism of cathodic electrodeposition of epoxy coatings and the corrosion behaviour of the electrodeposited coatings

The model of organic film growth on a cathode during electrodeposition process proposes the current density-time and film thickness-time relationships and enables the evaluation of the rate contents for the electrochemical reaction of OH? ion evolution and for the chemical reaction of organic film deposition. The dependencies of film thickness and rate constants on the applied voltage, bath temperature and resin concentration in the electrodeposition bath have also been obtained. The deposition parameters have a great effect on the cathodic electrodeposition process and on the protective properties of the obtained electrodeposited coatings. From the time dependencies of the pore resistance, coating capacitance and relative permittivity, obtained from impedance measurements, the effect of applied voltage, bath temperature and resin concentration on the protective properties of electrodeposited coatings has been shown. Using electrochemical impedance spectroscopy, thermogravimetric analysis gravimetric liquid sorption experiments, differential scanning calorimetry and optical miscroscopy, the corrosion stability of epoxy coatings was investigated. A mechanism for the penetration of electrolyte through an organic coating has been suggested and the shape and dimensions of the conducting macropores have been determined. It was shown that conduction through a coating depends only on the conduction through the macropores although the quantity of electrolyte in the micropores of the polymer net is about one order of magnitude greater than that inside the conducting macropores.

The electrolytic preparation and physical characterization of ZrTiO 4 films

An electrolytic method for the preparation of ceramic films is reported. ZTiO 4 films were deposited on a graphite substrate by cathodic electrodeposition process with the aid of a peroxoprecursor. The properties of the deposition solution were investigated using colorimetrical method and an NMR technique. Structural investigations of the films were carried out using programmed thermodesorption method in association with interferometric scanning microscopy and an X-ray diffraction technique. These studies provided an explanation for some of the characteristics of thin films. Heat treatment of the films was used to develop crystalline characteristics in the films.

The effect of concentration on the cathodic electrodeposition process

The effect of resin concentration on the final film thickness and on the rate constant during the cathodic electrodeposition of a polymer has been investigated using a constant voltage method. It was found that the film thickness and the rate constant increased linearly with resin concentration, supporting the assumption that the chemical reaction occurring during organic film deposition is pseudo-first order.

The effect of applied voltage on the cathodic electrodeposition process

The effect of applied voltage on the final film thickness and the rate constant during the cathodic electrodeposition process has been investigated by a constant voltage method. It was shown that the film thickness increases linearly with applied voltage and this was explained analytically. The rate constant increases exponentially with applied voltage.

The kinetics of organic film growth during the cathodic electrodeposition process

The kinetics and the mechanism of organic film growth during the cathodic electrodeposition process are investigated by galvanostatic and constant voltage methods. Constant voltage experiments carried out at lower voltages enabled the more accurate observation of current density changes and enabled the proposal of a mathematical model which gives a consistent picture of film growth kinetics. It was shown that the film thickness increases with time but a limiting value was not achieved.