Electrodeposition Solution Research Articles

Hydrogen evolution assisted electrodeposition of bimetallic 3D nano/micro-porous PtPd films and their electrocatalytic performance

Self-supporting PtPd bimetallic catalysts with three-dimensional (3D) porous structures and a greatly enhanced surface area are firstly fabricated at a glassy carbon electrode (GCE) by a one-step strategy of potentiostatic co-electrodeposition utilizing hydrogen bubble dynamic templates. The atomic ratio of Pt/Pd in the bimetallic catalysts is varied by changing the composition of the electrodeposition solution. The 3D porous PtPd films are characterized by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) and examined as electrocatalysts for the electro-oxidation of methanol using cyclic voltammetry (CV), chronoamperometry and electrochemical impedance spectroscopy (EIS). Experimental results demonstrate that a small amount of Pd plays the predominant role in the formation of 3D porous structure for PtPd bimetallic catalysts and is an excellent catalytically enhancing agent for the Pt catalyst towards methanol electro-oxidation. The study on electrocatalytic performance of mono and bimetallic catalysts towards formic acid electro-oxidation also reveals the better activity of 3D porous Pd film for this reaction.

A study on electrodeposition of Ni-noncovalnetly treated carbon nanotubes nanocomposite coatings with desirable mechanical and anti-corrosion properties

In this study, we report on the successful incorporation of non-covalently functionalized multi-wall carbon nanotubes (MWCNTs) in electrodeposition bath using a multi-step dissolution to enhance dispersing and untangling. We observed that a saturation concentration exists for CNT dispersion in the electrodeposition solution and consequently an optimum condition for electrodeposition of Ni-MWCNT was obtained at a current density of 4A/dm2, and CNT concentration of 2g/l. X-ray diffraction spectrum revealed a remarkable effect of CNTs on the texture, crystallite size, and internal micro-strain of the coatings. On the basis of nanoindentation and micro-hardness tests, increased hardness and elastic modulus of the coatings were observed which directly depend upon CNT content of the composite coating. Corrosion study results in 3.5% sodium chloride solution showed that corrosion rate decreases with increase in CNT content, though the corrosion rate is directly influenced by nickel crystallite size.

Single-step electrodeposition of CIS thin films with the complexing agent triethanolamine

Some difficulties have long been encountered by single-step electrodeposition such as the optimization of electrolyte composition, deposition potentials, deposition time, and pH values. The approach of introducing ternary components into single-step electrodeposition is rather challenging especially due to the different values of the equilibrium potential for each constituent. Complexing agents play an important role in single-step electrodeposition of CuInSe2 (CIS), since the equilibrium potential of every constituent can be brought closer to each other when complexing agents are employed. In this work, single-step electrodeposition of CIS was enhanced by adding triethanolamine (TEA) into deposition bath, the CIS thin films were improved consequently in the form of polycrystalline cauliflower structures through the examination of SEM images and XRD patterns. The optimum composition of the solution for single-step electrodeposition of CIS is found to be 5mM CuCl2, 22mM InCl3, and 22mM SeO2 at pH 1.5 with 0.1M TEA. The structures, compositions, and morphologies of as-deposited and of annealed films were investigated.

Fabrication of bowl-like porous WO3 film by colloidal crystal template-assisted electrodeposition method

Large scale of bowl-like porous WO3 film was successfully fabricated by electrodeposition into two-dimensional (2D) polystyrene (PS) colloidal crystal template. The technological process involved the following steps: colloidal crystal template preparation, potentiostatic electrodeposition of WO3 into the template, and template removal. 1.5 μm PS spheres were used to prepare the 2D colloidal crystal template by means of spinning on indium-tin-oxide (ITO) glass. A two-electrode cell was used for electrodeposition, in which the anode was graphite and the cathode was PS-coated ITO glass. The electrodeposition solution consisted of 25 mM Na2WO4 and 30 % H2O2 acidified at pH 1.2. Via electrodeposition, the interstitial space of the densely packed PS colloidal crystal template was filled with WO3. Bowl-like porous WO3 film was obtained after the removal of the PS colloidal crystal template by a thermal treatment at 475 °C. Scanning electron microscopic, X-ray diffraction spectra and transmission electron microscopy were performed to analyze and compare bowl-like porous WO3 film with dense WO3 film. The homogeneous area of the obtained film was 25 × 15 mm2. The template-assisted electrodeposition method was simple and low-cost that can be completed within 30 min.

Dendritic copper-cobalt nanostructures/reduced graphene oxide-chitosan modified glassy carbon electrode for glucose sensing

A novel nonenzymatic glucose sensor was developed by electrodepositing dendritic copper-cobalt nanostructures (Cu-Co NSs) on glassy carbon electrode (GCE) which was modified by reduced grapheme oxide-chitosan (RGO-CHIT) nanocomposites. The electrochemical behaviors and electrocatalytic performances of the sensor towards oxidation of glucose were evaluated by cyclic voltammograms, chronoamperometry and amperometric method. Compared to sensors based on monometal Cu or Co NSs, the sensor based on bimetal Cu-Co NSs exhibits good electrocatalytic activity towards oxidation of glucose. The effects of electrodeposition time and the ratio of Cu2+ and Co2+ in an electrodeposition solution on the electrocatalytic performance of the Cu-Co NSs sensor were explored in detail. The best catalytic activity towards oxidation of glucose can be achieved under an optimized condition: electrodepositing time of 2600 s and the Cu2+/Co2+ molar ratio of 2:1. The catalytic current density is linear to the glucose concentration in the range of 0.015–6.95mM (r=0.9947) with a sensitivity of 1921μAcm−2mM−1, and a detection limit of 10μM. The good catalytic activity, high sensitivity and good stability indicate that the newly developed sensor based on the dendritic Cu-Co NSs/RGO-CHIT/GCE is a promising sensor for application in real samples.

Preparation and characterization of PbO2 electrodes from electro-deposition solutions with different copper concentration

The present work focused on studying the effect of Cu2+ concentration on the electrochemical properties of lead dioxide electrodes prepared by electrochemical deposition method. The surface morphology and the structure of the electrodes were characterized by scanning electronic microscopy (SEM) and X-ray diffraction (XRD), respectively. The stability and electrochemical activity of the lead dioxide electrodes were investigated by accelerated life test, linear sweep voltammetry and bulk electrolysis. The results showed that Cu2+ significantly decreased the grain size of lead dioxide and formed a compact and fine surface coating. The service lifetime of the copper modified lead dioxide electrode was longer than that of the unmodified electrode. The electrode prepared from the solution containing 0.2 mol L−1 copper nitrate (marked as PbO2-0.2 M electrode) showed the longest service life (49 h). During the linear sweep test, the PbO2-0.2 M electrode showed the highest electrochemical activity that can be attributed to its highest voltammetric charge quantity. Consequently, the PbO2-0.2 M electrode showed the best performance on degradation of Acid Red G in simulated wastewater by bulk electrolysis. Its pseudo first-order kinetics coefficient was 0.02552 min−1.

Large Platinum Structures as Promising Catalysts for the Oxygen‐Reduction Reaction

AbstractHerein, Pt and Pd catalysts (in the absence and presence of Fe, concomitantly or not with rutin or quercetin), PtPd and PtAu alloys, and Pt under Au are generated on a glassy carbon (GC) surface by using direct electrodeposition. The electrochemical profiles of these materials are investigated by using cyclic voltammetry and microgravimetry (electrochemical quartz crystal microbalance). Their electrocatalytic activity toward the oxygen‐reduction reaction (ORR) is studied by using hydrodynamic cyclic voltammetry. Physical characterization of the samples is performed by using SEM and energy‐dispersive X‐ray microanalysis. Electrodeposited catalysts that contain Pt exhibit high electrocatalytic activity toward the ORR and reproducible response, in particular at low Pt concentrations in the electrodeposition solution, thus suggesting the possibility of applying these catalysts to acid fuel cells. Large nanorock structures are formed on the GC electrode that is modified with Pt(0.50)/Pd(0.50)+rutin, whereas the GC electrode that is modified with Pd in the presence or absence of Fe, concomitantly or not with rutin or quercetin, shows poor electrocatalytic activity.

Corrosion behaviors of hydroxyapatite coated by electrodeposition method of Ti6Al4V, Ti and AISI 316L SS substrates

Electrodeposition method was used to obtain hydroxyapatite (HAP) coatings on Ti6Al4V, Ti and AISI 316L SS substrates. Electrodeposition solution is prepared as Ca(NO3)2 · 4H2O and (NH4)H2PO4. Additionally, three different pretreatment surface operations (PTSO) (HNO3, anodic polarization, baseacid) were applied to the substrates. Surface morphology of HAP coated substrates were characterized by SEM, EDS, XRD. HAP coatings were successfully deposited on Ti6Al4V, AISI 316L SS and Ti substrates Corrosion behavior of uncoated and HAP coated substrates were examined in the Ringer and 0.9% NaCl solutions. The XRD, SEM-EDS results supported that HAP formation on the substrates. i cor values for all three HAP coated substrates are higher than uncoated substrates This showed that, electrochemical deposition HAP coating could not prevent the corrosion. The lowest corrosion rates were founded HNO3 PTSO substrates.

Effect of the diffusion rate of the copper ions on the co-electrodeposition of copper and nickel

This study experimentally analyzed the influence of the diffusion rate of Cu ions on the growth of microstrucutres during the coelectrodeposition of copper and nickel. To change the diffusion rate of the Cu ions resolved in the electrodeposition solution, electrodeposition was performed under three different stirring conditions (0, 150, 300 rpm). The microstructure grew in an orientation vertical to the microstructure, similar to a probe without stirring, while a popcorn-shaped cluster with electrodeposition particles at the upper part of the microstructure was found under the stirring condition. Forced circulation of the electrodeposition solution by stirring drastically enhanced the movement of the Cu ions, and popcorn shaped clusters are formed. The average height and width of the structure electrodeposited for 20 minutes through stirring at 300 rpm were 1.5 and 4.3 times greater, respectively, than those of the structure electrodeposited without stirring. The substrate surfaces covered with electrodeposited microstructures were modified to be superhydrophobic by coating them with hydrophobic plasma polymerized fluorocarbon (PPFC).

Creation of microstructured surfaces using Cu–Ni composite electrodeposition and their application to superhydrophobic surfaces

This research analyzed the influence of the electrodeposition ratio of Cu–Ni on the creation of microstructure in Cu–Ni composite electrodeposition, and identified the microstructure generation mechanism with respect to the Cu–Ni electrodeposition ratio. The concentration of CuSO4 in the electrodeposition solution was varied to 0.00, 0.02, 0.04M to control the electrodeposition ratio of Cu, and the applied voltage was varied to voltages of −0.9, −1.2, −1.5V, which were applied to control the electrodeposition ratio of Ni. In the composite electrodeposition, Cu ions precipitated intensively at the top of the structure with a short ion diffusion length, and the Ni ions precipitated regularly throughout the entire area charge transferred. Therefore, the structure showed vertically oriented growth when Cu electrodeposition was dominant, and the structure showed isotropic growth when Ni electrodeposition was dominant. On the other hand, Cu ions precipitation concentration at the tip of the grown structure intensified as the height of the structure increased. Therefore, when a structure grows above a certain height, the excess Cu ions precipitate at the top of the grown structure and a cluster structure composed of spherical Cu particles develops. The microstructure produced in the electrodeposition solution with the CuSO4 concentration of 0.04M had such a high structure generation density and aspect ratio that it was modified to a superhydrophobic surface with a contact angle higher than 150°, and it manifested an excellent self-cleaning ability.

Characterization of PbO2 coating electrodeposited onto stainless steel 316L substrate for using as PEMFC's bipolar plates

Lead dioxide coatings were electrodeposited onto stainless steel 316L substrates in a fluoride containing plumbite solution with the aim of serving as bipolar plates in PEMFCs. According to XRD results, coatings are composed of non-stoichiometric α-Pb0.828O2 with less than 100nm crystallite size. SEM micrographs revealed that the presence of fluoride ions in electrodeposition solution does not alter the morphology of coatings. Electrical resistivity measurements suggest that fluorine substitutes oxygen in oxide lattice, thereby enhancing electrical conductivity as donor agents. Potentiodynamic polarization results in PEMFC simulated solution prove that the corrosion current density of lead dioxide coated specimens has decreased, at least by three-fold. There is also some evidence that coatings are susceptible to localized corrosion and PbO2/PbSO4 reaction may play an important role in this regard.

Zinc electrodeposition from alkaline solution containing trisodium nitrilotriacetic added

Abstract An alkaline solution for the electrodeposition of Zn was developed, with trisodium nitrilotriacetic (NTA) as the complexing agent for Zn(II). The voltammetric studies showed that the NTA has a beneficial effect, displacing the initial reduction potential of Zn(II) species to more positive values than in its absence. Cyclic voltammetry of 1010 steel in alkaline Zn electrodeposition solution with 0.20 M NTA indicated the occurrence of the Zn underpotential electrodeposition, UPD, (regions wave c ′ and c ″) and followed by Zn overpotential electrodeposition, OPD (region peak c ‴). The Zn electrodeposit produced voltammetrically at limiting potential ( E f ) −0.81 V (region wave c ′) was characterized by XRF and showed Zn presence. Zn electrodeposits produced potentiostatically at a potential −1.26 V were characterized by means of SEM, EDS and XRD. SEM results showed that fine-grain and compact Zn electrodeposits were obtained in the presence of 0.20 M NTA, at an electrodeposition charge density ( q d ) of 10.0 C cm −2 . AFM analysis showed that the roughness of the Zn electrodeposits is greater in the presence than absence of 0.20 M NTA to both q d 2.0 and 10.0 C cm −2 . The adhesion test showed that the Zn electrodeposits, in general, had no area detached. The XRD pattern revealed that the Zn electrodeposits had a crystal structure with preferential orientation [0 0 2]. It was showed that NTA was a suitable complexing agent for the electrodeposition of Zn without dendrites and cracks.

Effects of electrodeposition parameters on morphology and properties of Zn–TiO2 composite coating

Compared to metallic coating, composite coating has more significant mechanical and tribological properties. In this study, titania particles that were codeposited with zinc on a plain carbon steel substrate were used as reinforcements. In addition, the mechanical and tribological properties of these coatings were studied. The effects of bath temperature, stirring rate of electrodeposition solution and concentration of titania in bath on the morphological, mechanical and tribological properties were also investigated. The electrodeposited samples were observed with optical microscope, scanning electron microscope and atomic force microscope. Then, the microhardness and wear properties of the samples were measured. Finally, the optimum degrees of these parameters were achieved to attain maximum codeposition of reinforcement particles, hardness degrees and wear resistance of coatings. The optimised degrees of bath temperature, solution stirring rate and titania concentration in the bath were found to be 40°C, 300 rev min−1 and 5 g L−1 respectively.

Bi-doped PbO2 anodes: Electrodeposition and physico-chemical properties

The influence of bismuth ions on kinetics of lead dioxide electrodeposition from methanesulfonate electrolytes and physico-chemical properties of obtained coatings were studied. Experimental results are consistent with a mechanism previously proposed in the literature for lead dioxide electrodeposition. The presence of bismuth ions in the electrodeposition solution causes a decrease of rate constants of lead dioxide formation due to co-adsorption phenomena. Deposits from solutions containing bismuth ions appear shiny dark grey, and show good adhesion to metal support. SEM images reveal a compact structure with spindle-shaped submicron and nanosized crystals and X-ray diffractograms demonstrated that incorporation of bismuth diminishes the size of crystal particles. Oxygen evolution was investigated to test electrocatalytic activity. It is shown, that oxygen overpotential on modified electrodes is significantly higher than on non-modified PbO2-electrode, which depends on bismuth content in deposit and segregation of bismuth that induces surface heterogeneity due to sites with different electroactivity for water oxidation.

Surfactant-free and template-free electrochemical approach to prepare well-dispersed Pt nanosheets and their high electrocatalytic activities for ammonia oxidation

A template-free, surfactant-free, simple electrochemical approach has been developed to prepare well-dispersed platinum (Pt) nanosheets. By simply changing the anions from SO42− to Cl− in the electrodeposition solution, the formed Pt deposits is changed from flower-like Pt particles consisting of aggregated Pt nanosheets to well-dispersed Pt nanosheets. The surface morphology and structure of the Pt particles/nanosheets were investigated by the scanning electron microscopy and X-ray diffraction. The amount of the Pt loading was measured by an inductively coupled plasma method. The electrocatalytic activity of the prepared Pt electrocatalysts for ammonia oxidation was characterized by cyclic voltammetry. The result showed that the well-dispersed Pt nanosheets exhibits 112% and 89% increase in the mass activity (MA) for the ammonia oxidation compared with the flower-like Pt particles and commercial Pt/C catalyst, respectively. The much improved MA of the well-dispersed Pt nanosheets is attributed to not only the increased electrochemically active surface area (ECSA), but also the specific activity (SA). For example, the well-dispersed Pt nanosheets shows 88% increase in the SA compared with the commercial Pt/C catalyst.

Carbon electrodes unmodified and decorated with silver nanoparticles for the determination of nitrite, nitrate and iodate

The determination of nitrate and iodate was carried out in samples of mineral water and iodized salt by electrochemical reduction at silver nanoparticles (AgNPs)-modified electrodes. AgNPs were deposited by conventional potentiostatic reduction of a AgNO3 solution on flexible pure graphite sheets (PGS) and glassy carbon (GC). The analytical performances of the electrodes based on PGS were comparable to those of modified GC. The novel material can be considered an alternative to the more common glassy carbon. By adding ammonia to the electrodeposition solution it was possible to overcome the problem of Ag+ adsorption on the electrode surface which caused high background currents and prevented measurements in samples with high concentration of Cl− anions.Nitrite determination by oxidation was not feasible on the AgNPs-modified supports, thus this analyte was detected at bare PGS and GC.

Fabrication of CuInS2 thin film by electrodeposition of Cu–In alloy

CuInS2 thin films of chalcopyrite structure were fabricated on indium tin oxide substrates by electrochemical co-deposition of copper–indium alloy layers at 1 atm, followed by sulphurization. Co-deposition potential was determined according to voltammetric study. The effect of deposition potential, concentration of complexing agent, and heat treatment temperature on the morphology and crystal structure of the obtained thin films was examined. Then the influence of heat treatment on the optical and photoelectrochemical performance of CuInS2 thin films was studied. In the electrodeposition solution containing 5 mM CuCl2, 5 mM InCl3 and 0.2 M triethanolamine at pH of 4.0, Cu2In alloy layers were observed at the deposition potential of −1000 mV (vs. saturated calomel electrode). After sulfurization, chalcopyrite CuInS1.5 thin films with the impurity elements of C and O were obtained. Those thin films exhibited p-type semiconductor behavior with the bandgap of about 1.5 eV. The conversion efficiency can be improved further by depositing PbS particles on the thin films.

Platinum Systems Electrodeposited in the Presence of Iron or Palladium on a Gold Surface Effectively Catalyze Oxygen Reduction Reaction

In this study, Pt and Pd catalysts (in the absence and presence of Fe) and a Pt–Pd alloy were generated on a polycrystalline Au surface by means of a direct electrodeposition approach. The electrochemical profile of these materials was investigated using cyclic voltammetry and microgravimetry (electrochemical quartz crystal microbalance). The electrocatalytic activity toward oxygen reduction reaction (ORR) was studied using hydrodynamic cyclic voltammetry. Physical characterization of samples was performed using scanning electron microscopy, energy dispersive X-ray microanalysis, and atomic force microscopy. Electrodeposited catalysts containing Pt exhibited high electrocatalytic activity toward ORR, stability in terms of specific activity, and repeatability of responses, even at low Pt concentrations in the electrodeposition solution, thus suggesting the possibility of applying these catalysts to acid fuel cells. The Au electrode modified with Pt(0.75)/Fe(0.25) exhibited a nanorounded, low-roughness structure, whereas the Au electrode modified with Pd(0.75)/Fe(0.25) showed poor electrocatalytic activity, a nanospaghetti-shaped structure, and enhanced roughness.

Aqueous DC Electrodeposition and Mechanism of Magnetic SmCo Alloys

Electrodeposition of Sm-Co magnetic alloys have previously been investigated using Hull cells, DC and pulse methods from aqueous media. The basic electrodeposition solution had been selected as lM samarium sulfamate, 0.05M cobalt sulfate and 0.15M glycine. Solution temperatures ranged from 25oC to 60oC. Increased current density (CD) and temperatures increase deposit Sm content of metallic SmCo alloys. Deposit Sm contents were obtained, with appropriate heat treatment, to produce the intermetallics: SmCo3 (25.0 at %), Sm2Co7, (22.2 at %), SmCo5 (16.7 at %) and Sm2Co17 (10.5 at %). The present work investigates the DC electrodeposition of SmCo alloys in varying aqueous solution constituents, their composition and operating conditions and to consider the coordination chemistry of SmCo ions and aminocarboxylates (glycine). The hydrogen atoms generated at the cathode surface provide the electrons for the sequence of stepwise reduction of Sm and Co in the polymeric glycine complexes to deposit SmCo alloys.

Electrochemical study of Ni deposition on carbon microfiber

Electrochemical deposition of Ni on individual carbon microfiber from unbuffered NiCl2 solutions was studied for surface functionalization. Electrochemical and micro-structural analyses have been utilized to reveal ion concentration, applied potential and solution pH effects on the deposit nucleation and growth. Metal deposition efficiency on the carbon surface from these aqueous solutions increases significantly with Ni ion concentration. Polycrystalline Ni are normally formed but small amount of Ni(OH)2 has been detected when the very low concentration solution is used. Ni electrodeposition on carbon microfiber surface changes from the progressive nucleation model at lower applied over-potentials to the instantaneous nucleation model at higher applied over-potentials before hydrogen evolution dominates. Compared to the conventionally used acidic Ni electrodeposition solutions, reproducible layered growth was observed within a wide range of deposition potentials due to formation of adsorbed intermediate layer.