Three-step Electrodeposition Research Articles

Fabrication of a high-performance symmetrical supercapacitor based on electrochemically interconnected Cu:NiO@rGO:PANI/NF electrodes

A three-step electrodeposition synthesis was carried out to prepare a nanocomposite electrode of copper-doped nickel oxide and reduced graphene oxide-doped polyaniline with synergistic effects. Nickel foam was utilized as a current collector. XRD, FTIR and XPS studies confirm the molecular bond formation and molecular phase of the produced materials. According to the EDS results, the rGO:PANI/NF electrode contains 0.29 % nitrogen (N), 17.39 % carbon (C), and 9.81 % oxygen (O), while the Cu:NiO@rGO:PANI/NF electrode contains 8.24 % copper (Cu), 9.22 % carbon (C), 7.21 % oxygen (O), and 0.72 % nitrogen (N). The electrochemical performance of rGO:PANI/NF and Cu:NiO@rGO:PANI/NF electrodes were tested in a three-electrode cell with 3 M KOH aqueous electrolyte. High specific capacitances of 644.5 and 807.1 Fg−1 are achieved with the rGO:PANI/NF and Cu:NiO@rGO:PANI/NF electrodes at a current density of 20 Ag−1, respectively. The Cu:NiO@rGOPANI/NF also has a lower charge transfer resistance (RCT = 0.9 Ω) than the rGO:PANI/NF electrode (RCT = 3.8 Ω). This means NiO plays a crucial role in facilitating the transportation of charges between rGO:PANI. NiO acts as a “superhighway” that enables efficient and speedy charge transport. The expanded BET surface area of Cu:NiO@rGO:PANI/NF can be attributed to a well-interconnected network of PANI chains with NiO. In order to demonstrate a further application, an all-solid-state symmetrical supercapacitor (SSC) was then fabricated using the Cu:NiO@rGO:PANI/NF electrodes. The operating potential range is between 0 and 1.5 V. The device has a good capacitance of 81.9 Fg−1 at 4.5 Ag−1, and a capacitance retention of 97.6 % at a specific current of 10 Ag−1 after 10,000 cycles. The symmetrical device has a maximum energy density of 25.6 Wh kg−1 at a high power density of 1297.6 W kg−1 at 4.5 A g−1. In light of these results, the nanocomposite-based solid-state supercapacitor is considered to be a promising device for the development of high-performance symmetric supercapacitors.

Electrosynthesis of dendritic palladium supported on Ti/TiO2NTs/Ni/CeO2 as high-performing and stable anode electrocatalyst for methanol electrooxidation

Liquid-fueled direct methanol fuel cell (DMFC) is highly promising for low-carbon transportation, but is hindered by high cost and short lifespan of conventional Pt-based electrocatalysts. Herein, we propose a new Pt-free catalyst strategy to exploit high-performing and stable electrocatalyst of DMFC, achieving enhanced electrocatalytic activity and high stability for methanol oxidation reaction (MOR) in alkaline media. A new Pt-free anode catalysts consisting of titanium/reduced-titanium dioxide nanotubes/nickel/cerium dioxide (Ti/r-TiO2NTs/Ni/CeO2) nanosupport and uniformly-dispersed Pd dendrites is successfully prepared by a facile three-step electrodeposition route without applying any template or surfactant. Noticeably, the as-prepared Ti/r-TiO2NTs/Ni/CeO2–Pd as an anode electrode exhibits superior activity than commercial Pd/C and other electrodes. The obtained large mass activity for Ti/r-TiO2NTs/Ni/CeO2–Pd electrode is 1752 mA mgPd−1 for MOR. After successive CV tests of 1000 cycles, Ti/r-TiO2NTs/Ni/CeO2–Pd electrode still retained 88.9% of its initial current. The superior performance of Ti/r-TiO2NTs/Ni/CeO2–Pd attributes to the large surface area and excellent conductivity, as well as the synergistic effects among nanosupport and Pd dendrites. Therefore, this study will open a new door for high-performance fuel cell applications.

Effect of i-ZnO seed layer on the properties of electrodeposited p-Cu2O/n-ZnO/FTO heterojunction thin films

In this study, p-Cu2O/n-ZnO/i-ZnO/FTO heterojunction have been successfully deposited via a simple three-step electrodeposition method. The effects of inserting ZnO seed layer on the properties of the heterojunctions were investigated using a variety of analysis techniques. Mott-Schottky analysis indicated p-type conductivity for Cu2O and n-type conductivity for ZnO thin films. X-ray diffraction (XRD) patterns indicated that the ZnO nanostructures were of polycrystalline nature with highly hexagonal ZnO (002) oriented crystallites and cubic structure of Cu2O having (111) preferential orientations. This was confirmed by field emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM) analysis revealed that the Cu2O/ZnO heterojunctions were composed of hexagonal grains in the underlying layers while the higher layer exhibited typical pyramids features. Also, experimental results pointed out that the insertion of the seed layer could produce denser microstructures, and improve compactness and surface flatness of the thin films. From UV-vis spectra, a blue shift of the bandgap with an obviously increase in the optical transparency to 80% were noted by the insertion of the seeding layer approach. Current-voltages (I-V) plots of Au/p-Cu2O/n-ZnO/i-ZnO/FTO heterojunctions showed excellent rectifying behavior, and their electrical characteristics can be effectively tuned through the contribution of ZnO seed layer. This study demonstrates the crucial role of seeding layer in the nucleation-growth and consequently in the properties of these heterojunctions.

Electrochemical synthesis of n-type ZnS layers on p-Cu2O/n-ZnO heterojunctions with different deposition temperatures.

Metal oxide p–n heterojunctions consisting of p-Cu2O/n-ZnO/n-ZnS nanostructures were deposited on an ITO substrate by three-step electrodeposition. The effect of ZnS layer deposition temperature on the properties of the heterojunction was investigated by different techniques. The Mott–Schottky analysis confirmed the n-type conductivity for ZnO and ZnS and p-type conductivity for the Cu2O layer, respectively. Also, it showed a decrease of ZnS donor concentration with increasing deposition temperature. The X-ray diffraction (XRD) analysis confirms a pure phase of hexagonal ZnO, cubic ZnS and cubic Cu2O structures, respectively. The heterojunction with ZnS deposited at 60 °C shows high crystallinity. The morphological measurements by scanning electron microscopy (SEM) indicate that the deposition temperature has a significant influence on the morphology of ZnO and the atomic force microscopy (AFM) images revealed the improvement of Cu2O morphology by increasing the ZnS deposition temperature. The UV-Vis response shows strong absorption in the visible region and the profile of optical absorption spectra changes with the ZnS deposition temperature. The current–voltage (I–V) characteristics of the Au/p-Cu2O/n-ZnO/n-ZnS/ITO heterojunction display well-defined rectifying behavior for the heterojunction with ZnS deposited at 60 °C.

Enhanced antibacterial properties of biocompatible titanium via electrochemically deposited Ag/TiO2 nanotubes and chitosan-gelatin-Ag-ZnO complex coating.

A novel double-layered antibacterial coating was fabricated on pure titanium (Ti) via a simple three-step electrodeposition process. Scanning electronic microscopy (SEM) images show that the coating was constructed with the inner layer of TiO2 nanotubes doped with silver nanoparticles (TNTs/Ag) and the outer layer of chitosan–gelatin mixture with zinc oxide and silver nanoparticles (CS–Gel–Ag–ZnO). In comparison, we also investigated the composition, structure and antibacterial properties of pure Ti coated with TNTs, TNTs/Ag or TNTs/Ag + CS–Gel–Ag–ZnO, respectively. The TNTs was about 100 nm wide and 240 nm to 370 nm tall, and most Ag nanoparticles (Ag NPs) with diameter smaller than 20 nm were successfully deposited inside the tubes. The CS–Gel–Ag–ZnO layer was continuous and uniform. Antibacterial activity against planktonic and adherent bacteria were both investigated. Agar diffusion test against Staphylococcus aureus (S. aureus) shows improved antibacterial capacity of the TNTs/Ag + CS–Gel–Ag–ZnO coating, with a clear zone of inhibition (ZOI) up to 14.5 mm wide. Dead adherent bacteria were found on the surface by SEM. The antibacterial rate against planktonic S. aureus was as high as 99.2% over the 24 h incubation period.

Effect of the thickness of the ZnO buffer layer on the properties of electrodeposited p-Cu2O/n-ZnO/n-AZO heterojunctions

Transparent conducting Cu2O/non-doped ZnO/Al-doped ZnO/FTO heterojunction solar cells were fabricated by a three-step electrodeposition; with non-doped ZnO film as a buffer layer between-AZO thin film and p-Cu2O nanostructure.

Effect of HAuCl4concentration on electrochemical DNA sensing behaviors of Au/nanoSPAN nanocomposite

Sensing properties of Au nanomaterials are greatly influenced by their morphology, size, and structure. Studying influencing factors to achieve controllable morphology, size and electrochemical properties is profoundly significant for further analytical applications. In this work, various Au micro-nanostructures were fabricated by varying the concentrations of HAuCl4 through a three-step electrodeposition method, in which self-doped polyaniline nanofibers (nanoSPAN) served as a supported matrix to obtain Au/nanoSPAN nanocomposite. The obtained electrodes were characterized by scanning electron microscopy, energy disperse X-ray spectroscopy and cyclic voltammetry (CV). The sulfonic acid groups and the imine units on the surface of nanoSPAN ensured the nucleation and growth of Au micro-nanostructures. Compared with other morphologies, the hierarchical and homogeneously dispersed flower-like Au microspheres (obtained in 5.0 mM HAuCl4 solution) showed high electrochemical activity in a 0.5 M H2SO4 solution and the largest electroactive areas. The next-step DNA sensing results based on various Au/nanoSPAN nanocomposites using methylene blue as electrochemical probe showed that controlling the concentrations of HAuCl4 can influence the amount of immobilized ssDNA and its sensitivity.

Three-step electrodeposition synthesis of self-doped polyaniline nanofiber-supported flower-like Au microspheres for high-performance biosensing of DNA hybridization recognition

A three-step electrodeposition method has been successfully adopted to fabricate morphology-controlled novel Au microspheres on self-doped polyaniline nanofibers (nanoSPAN) modified glassy carbon electrode. The deposition conditions, such as HAuCl4 concentration and deposition step, have significant influences on the morphologies and electrochemical properties of the resulted Au microspheres. Well hierarchical and homogeneously dispersed flower-like Au microspheres (HHFAu) were obtained under optimal conditions by the three-step electrodeposition strategy in 5.0mM HAuCl4 solution. HHFAu possess large surface area, excellent electron transfer ability and good biocompatibility. The DNA probe could be effectively attached to HHFAu and thus a high-performance DNA biosensor was constructed by using electrochemical impedance spectroscopy as detection method. A gene fragment of the cauliflower mosaic virus 35S gene, which is related to one of the screening genes for the transgenically modified plants, has been satisfactorily detected. The linear range was from 1.0×10−13M to 1.0×10−6M and the detection limit was 1.9×10−14M. This HHFAu/nanoSPAN-based impedance biosensing platform holds great promise for the detection of other biological and chemical molecules.

Controllable fabrication of Au micro/nanostructures on self-doped polyaniline nanofibers via electrochemical deposition and its application for DNA immobilization

Four electrochemical methods, cyclic voltammetric deposition, potentiostatic electrodeposition, multi-potential step electrodeposition and three-step electrodeposition, were used to fabricate Au micro/nanostructures on self-doped polyaniline nanofibers-coated glassy carbon electrodes (Au/nanoSPAN/GCEs). The Au micro/nanostructures deposited on the nanoSPAN-modified electrodes were shown by scanning electron microscopy to exhibit different morphologies, such as Au nanoparticle clusters, monodisperse nanoparticles and homogeneously dispersed flower-like microparticles, depending on the deposition method. This phenomenon demonstrates that control over the morphology of Au metal can be easily achieved by adjusting the electrodeposition method. The electrochemical behaviors of the Au/nanoSPAN/GCEs also varied with above four methods, which were characterized by cyclic voltammetry and electrochemical impedance spectroscopy. In comparison with Au nanoparticle clusters and monodisperse Au nanoparticles, homogeneously dispersed flower-like Au microparticles had the largest surface area and obviously enhanced electrochemical response towards the redox reactions of [Fe(CN)6]3−/4− on the modified electrode. DNA immobilization on the Au/nanoSPAN/GCEs was investigated by differential pulse voltammetry using [Fe(CN)6]3−/4− as an indicator. The efficiency of DNA immobilization was inherently related to their different Au micro/nanostructure morphologies. The Au/nano-SPAN/GCE fabricated by three-step electrodeposition showed the largest capacity for immobilization of single stranded DNA, which makes it a promising DNA biosensor.

Electrodeposition of High-Tc Superconducting Bi-Sr-Ca-CuO Nanostructures

We report on the reproducible growth of superconducting (Bi1-xPbx)2Sr2CuO6+δ and (Bi1-xPbx)2Sr2Ca2Cu3O10+δ nanostructures, which has been a major difficulty in the electrochemical deposition of thin films of BSCCO. The precursors of superconducting Bi(Pb)-Sr-Ca-CuO were electrodeposited in an electrolytic bath prepared from the nitrate salts of the constituent metals in an organic solvent, dimethylsulfoxide (DMSO). The superconductor was electrodeposited in the form of nanotubes and nanowires. The as-deposited samples were given a controlled oxidative thermal treatment in air. The influence of deposition potential, annealing temperature and pH was studied and optimized to get the desired stoichiometry, 2201 and 2223 phase of superconducting Bi(Pb)-Sr-Ca-CuO. A novel three-step electrodeposition scheme was implemented to control the elemental stoichiometry specifically, the oxygen stoichiometry in the sample. Characterization of the electrodeposited and annealed nanostructures was done using XRD, EDS, SEM and PPMS. A plausible theoretical interpretation is given to explain the purpose behind the electrodepositing nanostructures.

Effects of fiber volume fraction, hot pressing parameters and alloying elements on tensile strength of carbon fiber reinforced copper matrix composite prepared by continuous three-step electrodeposition

Carbon fiber reinforced copper matrix composites have been produced by continuous three-step electrodeposition plus hot pressing technique. Iron or nickel element was added to copper matrix to improve interfacial bonding of the composite. The effects of fiber volume fraction and hot pressing parameters (temperature, pressure and time) on the tensile strength of the composite were investigated. Emphasis was placed on the influence of alloying elements on the tensile strength of the composite. The composite was found to exhibit the highest strength at an optimum V f, hot pressing parameter temperature, pressure, or time by keeping other parameters constant. This optimum value was related to the alloying element incorporated in the copper matrix. It is observed that incorporation of alloying elements does not change the general trends, but changes the mechanism governing the decreasing trends of the tensile strength of the composites as the hot pressing temperature exceeds the optimum value. Further, the alloying elements affect the highest strength values ( σ max). C/Cu(Ni) composite with the medium interfacial bonding strength exhibits the highest σ max. It is concluded from our experiments that a diffusion bonding is preferable since the fiber–matrix interaction can be easily controlled and the fiber degradation is limited during hot pressing process.

Fabrication and properties of carbon fibre-reinforced copper composite by controlled three-step electrodeposition

Fabrication and properties of continuum carbon fibre-reinforced copper materials by controlled three-step electrodeposition are described. The effects of processing parameters, i.e. hot-pressing temperature, pressure and duration, and reinforcement content, on the properties of composites are discussed. An alloying element, nickel, was introduced into the C/Cu interface to enhance the composite strength. Finally, the relatively optimum production parameters (i.e. 30 wt% fibre, 700°C, 40 min and 10 MPa) are suggested.