Pulsed Electrochemical Deposition Research Articles

Biocompatibility of Mg Ion Doped Hydroxyapatite Films on Ti-6Al-4V Surface by Electrochemical Deposition.

In this study, we prepared magnesium (Mg) doped nano-phase hydroxyapatite (HAp) films on the TiO2 nano-network surface using electrochemical deposition method. Ti-6Al-4V ELI surface was anodized in 5 M NaOH solution at 0.3 A for 10 min. Nano-network TiO2 surface were formed by these anodization steps which acted as templates and anchorage for growth of the Mg doped HAp during subsequent pulsed electrochemical deposition process at 85 degrees C. The phase and morphologies of HAp deposits were influenced by the Mg ion concentration.

Facile electrosynthesis, characterisation and electrochemical performance of poly ortho aminophenol/Al5Y3O12 nanocomposite as a new high efficient supercapacitor

In this paper, firstly Al5Y3O12 has been synthesized without any impurities using pulse electrochemical deposition and then fabricated POAP/YAG films to serve as the active electrode for the electrochemical supercapacitor.

Morphology and composition of coatings based on hydroxyapatite-chitosan-RuCl3 system on AZ91D prepared by pulsed electrochemical deposition

Hydrxoyapatite-chitosan-RuCl3 nanocomposite coatings were pulsed electrochemical deposited on magnesium alloys AZ91D and studied using scanning electron microscope (SEM), X-ray diffraction (XRD), energy-dispersion spectrometer (EDS), electron probe micro-analysis (EMPA), auger electron spectroscopy (AES) and Fourier transform infrared spectroscopy (FTIR). The corrosion resistance of coating was examined by impedance measurements and potentiodynamic polarization. It was shown that the coatings can be varied by the variation of RuCl3 concentration in the solutions used for pulsed electrochemical deposition (PED). The absorption rate of Ru element on composite coatings was varied in the range of 35.02%∼51.62% by the variation of RuCl3 concentration from 2.1 mmol L−1 to 8.4 mmol L−1 in electrolyte. The hydroxyapatite grain of the obtained coating was refined to 180 nm, which could be explained by this mechanism: the electronegativity value of Ru was higher than Ca, which resulted in the new formation of PO43− tended to prefer attracting RuCl3 firstly on the cathode. Moreover, electrochemical impedance spectroscopy and potentiodynamic polarization studies showed that higher RuCl3 absorption rate on the coating provide corrosion protection of AZ91D in Hank's solution. With higher RuCl3 absorption rate, the induced hydroxyapatite-forming ability of the composite coating in Hank's solution has improved remarkably. The composite coatings are promising materials for the fabrication of implantable bio-materials with advanced functions properties.

Spectroelectrochemical Analysis of Charge Carriers as a Way of Improving Poly(p-phenylene)-Based Electrochromic Windows

We show the electrochemical polymerization and characteristic of six p-phenylene derivatives. The electroactive comonomers and polymers containing furan, thiophene, and selenophene units are studied using electrochemical techniques (differential pulse voltammetry, cyclic voltammetry, electrochemical deposition, and voltabsorptiometry) in order to characterize layers, charge carriers, and energy electronic levels. The possibility of using such polymers as electrochromic windows is presented. Simple evaluation of charge carriers helps to explain the long switching time of electrochromic window.

Ultra-high-performance core-shell structured Ru@Pt/C catalyst prepared by a facile pulse electrochemical deposition method.

Core–shell structured catalysts, made by placing either a monolayer or a thin layer of a noble metal on relatively cheap core-metal nanoparticles, are fascinating and promising fuel cell catalysts due to their high utilization of noble metals. Here, we report our development of a core–shell structured catalyst, Ru@Pt/C, generated by a novel and facile pulse electrochemical deposition (PED) approach. We demonstrate that compared with a commercial Pt/C catalyst, this novel catalyst achieves over four times higher mass activity towards the anodic oxidation of methanol, and 3.6 times higher mass activity towards the cathodic reduction of oxygen. Importantly, we find that the intrinsic activity of Pt in this Ru@Pt/C catalyst is doubled due to the formation of the core–shell structure. The catalyst also shows superior stability: even after 2000 scans, it still retains up to 90% of the peak current. Our findings demonstrate that this novel PED approach is a promising method for preparing high-performance core–shell catalysts for fuel cell applications.

Structural and compositional characterization of Bi1−xSbx nanowire arrays grown by pulsed deposition to improve growth uniformity

Arrays of Bi1−xSbx nanowire with various compositions (0⩽x⩽1) are grown in etched ion-track membranes by pulsed electrochemical deposition. Nanowires of diameter from 130nm down to 18nm are characterized by means of X-ray diffraction and high-resolution electron microscopy combined with electron diffraction and energy dispersive X-ray analysis. Compared to potentiostatic deposition, the pulsed synthesis method leads to a more uniform growth and higher filling rate of the wires across the entire template. By tuning the deposition parameters, we demonstrate excellent control over the wire composition and crystallographic orientation. The deposition process presented facilitates the development of future nanowire-based thermoelectric sensors, which are expected to exhibit a higher sensitivity and a faster response compared to thin film sensors.

(Invited) Optimizations of p and n-Type Bi2Te3-Based Ternary Compounds By Ms-Pulsed Plating and Annealing Under Telluride Atmospheres

In this work, a comprehensive study of thermoelectric chalcogenide materials is presented and the systematic optimization of n-type Bi2Te3, p-type Sb2Te3 and their ternary compounds is performed. Thermoelectric materials are synthesized by potentiostatic electrodeposition on Au/Pt and stainless steel substrates. The influence of the preparative parameters such as the composition of the electrolyte bath and the deposition potential is investigated in a nitric acid solution. As a post-deposition step, the influence of annealing of the films is investigated. The use of a potential-controlled millisecond-pulsed deposition method improves both the morphology and the composition of the films. For n-doped films, approximately -100 µV K−1 (Bi2Te3) and -130 µV K−1 (Bi2(TexSe1−x)3) are achieved. Power factors and ZT values for p-type and n-type ternary alloys of up to 1325 µW m−1K−2 (ZT=0.4) and 825 µW m−1K−2 (ZT=0.3) are realized, respectively. In conclusions, the thermoelectric perform have been improved by one to two orders of magnitude in comparison to previously electrochemical synthesized thermoelectric layers. Based on the electrochemical synthesis and subsequent balancing of the stoichiometry by annealing under Te atmosphere, have resulted in bulk-like power-factors. Millisecond pulsed electrochemical deposition is also a quite flexible approach for achieving nanowires of ternary chalcogenide compounds, which are grown in nanoscale confined spaces. After the annealing in Te enhanced the transport properties, on single Bi2(Te1-xSex)3 and (Bix-1Sbx)2Te3 nanowires power factors of 3100 mW K-2 m-1 and of 1600 mW K-2 m-1 with nearly bulk-like properties are achieved, respectively. Furthermore, we present magneto-resistance measurements on the Bi2Te3 and Sb2Te3 nanowires, which show clear evidences of topological surface states.The financial support by the German Ministry of Science and Educations (BMBF) and by the German Priority Program DFG-SPP 1386 on Thermoelectric Nanostructures is gratefully acknowledged: www.spp1386thermoelectrics.de

Pulsed electrochemical deposition of Pt NPs on polybenzimidazole-CNT hybrid electrode for high-temperature proton exchange membrane fuel cells

Nitrogen-doped CNTs, directly grown on a carbon cloth (CNT/CC) hybrid with polybenzimidazole (PBI), are utilized as hybrid electrodes in high-temperature proton exchange membrane fuel cells (HT-PEMFCs). The use of a rotation holder for pulse electrodepositing Pt nanoparticles (NPs) on a CNT electrode is developed herein. The electrochemical surface area of the Pt NPs/PBI-CNTs is approximately 161 cm2 mg−1 and the grain size is around 8–9 nm. A comparative study of 0.09 mg cm−2 Pt NPs on a PBI–CNT (Pt/PBI–CNT) electrode and 0.8 mg cm−2 Pt NPs on PBI–carbon black (Pt/PBI–CB) for reducing oxygen at the cathode was carried out. In H2/O2 HT-PEMFC single cell tests, a low Pt-loaded (0.09 mg cm−2) Pt/PBI–CNT/CC electrode outperformed a high Pt-loaded (0.8 mg cm−2) Pt/PBI–CB/CC electrode with maximum power densities of 620 mW cm−2 and 468 mW cm−2, respectively, at 160 °C. The enhanced performance is attributed to the well-controlled grain size and Pt loading of Pt NPs on the PBI-CNT in the cathode, which provide the highly active catalyst and the good electrical conductivity carbon support.

Electrochemically designed interfaces: Hydroxyapatite coated macro-mesoporous titania surfaces

Titanium-based implants are key weight-bearing materials in biomedical engineering due to their excellent bulk mechanical properties and biocompatibility. Designing tissue-material interfaces of titanium implants is essential for an increase in osteointegration of engineered implant materials. Surface morphology is a crucial determinant in the construction of biocompatible and osteointegrative orthopedic and dental implants. Biomimicry of the structural features of bone, specifically its macro-to-mesoporosity, may enable the bone cells to osteointegrate, attain and maintain a physiological strain level. In this study, the surface chemistry and morphology of commercially pure titanium plates were modified using electrochemistry. Titanium oxide substrates were prepared by dual acid polishing and alkaline anodization using 0.1M KOH in an electrochemical cell with a stainless steel cathode and an anodic voltage of 40V at 20°C for 3min. FE-SEM characterization revealed macro-mesoporous anodized titania surfaces, which were coated by hydroxyapatite using simulated body fluid and pulsed electrochemical deposition at 80°C, while unprocessed commercially pure titanium surfaces were used as controls. The calcium phosphate deposit on titania plates was characterized as calcium-deficient carbonated hydroxyapatite using XRD, FTIR and FE-SEM, whereas the deposit on non-porous, non-functionalized titanium surfaces was characterized as carbonated apatite. The adhesion strength of the hydroxyapatite coated titania surfaces was 38±10MPa, implying that these surfaces may be suitable for biological and chemical functionalization of medical implants to tune bioactivity, including delivering drugs.

Formation and Characterization of Hydroxyapatite Coating Prepared by Pulsed Electrochemical Deposition

Abstract Hydroxyapatite coatings were prepared on magnesium alloy AZ91D by pulsed electrochemical deposition. The effects of electrochemical deposition parameters such as pulsed voltage, electrochemical deposition time and electrolyte additive on the morphology, the microstructure, the composition, the coating thickness and electrochemical properties were tested. The results show that at 110 V, the coating with lower porosity, more homogeneous surface and nanometer particles can be obtained, which also has higher XRD diffraction peaks. The morphology and the microstructure of hydroxyapatite particles of the samples prepared in Ca-P electrolyte with NaNO 3 and H 2 O 2 addition at 110 V are optimized. The corrosion resistance of the prepared coating is enhanced in potentiodynamic polarization and electrochemical impedance tests. Moreover, immersion test results indicate that such a coating is beneficial to hydroxyapatite formation and enhancing the bioactivity in simulated solution.

Electrochemical deposition of molybdenum sulfide thin films on conductive plastic substrates as platinum-free flexible counter electrodes for dye-sensitized solar cells

In this study, pulsed electrochemical deposition (pulsed ECD) was used to deposit molybdenum sulfide (MoSx) thin films on indium tin oxide/polyethylene naphthalate (ITO/PEN) substrates as flexible counter electrodes (CEs) for dye-sensitized solar cells (DSSCs). The surface morphologies and elemental distributions of the prepared MoSx thin films were examined using field-emission scanning electron microscope (FE-SEM) equipped with energy-dispersive X-ray spectroscopy. The chemical states and crystallinities of the prepared MoSx thin films were examined by X-ray photoelectron spectroscopy and X-ray diffraction, respectively. The optical transmission (T (%)) properties of the prepared MoSx samples were determined by ultraviolet–visible spectrophotometry. Cyclic voltammetry (CV) and Tafel-polarization measurements were performed to analyze the electrochemical properties and catalytic activities of the thin films for redox reactions. The FE-SEM results showed that the MoSx thin films were deposited uniformly on the ITO/PEN flexible substrates via the pulsed ECD method. The CV and Tafel-polarization curve measurements demonstrated that the deposited MoSx thin films exhibited excellent performances for the reduction of triiodide ions. The photoelectric conversion efficiency (PCE) of the DSSC produced with the pulsed ECD MoSx thin-film CE was examined by a solar simulator. In combination with a dye-sensitized TiO2 working electrode and an iodine-based electrolyte, the DSSC with the MoSx flexible CE showed a PCE of 4.39% under an illumination of AM 1.5 (100mWcm−2). Thus, we report that the MoSx thin films are active catalysts for triiodide reduction. The MoSx thin films are prepared at room temperature and atmospheric pressure and in a simple and rapid manner. This is an important practical contribution to the production of flexible low-cost thin-film CEs based on plastic substrates. The MoSx thin films produced by pulsed ECD are good candidates for catalysts in flexible DSSCs.

Antireflective nanostructured zinc oxide arrays produced by pulsed electrodeposition

Conditions for the pulsed electrochemical deposition of nanostructured zinc oxide arrays with a certain morphology, crystal structure, and optical properties from aqueous electrolytes onto substrates of transparent electrically conducting tin dioxide and on single-crystal silicon wafers with built-in homojunctions are studied in order to develop antireflection coatings for solar cells. It is shown that it is possible to obtain single-layer planar antireflection coatings or arrays of nanorods of this material, both having the form of hexagonal prisms and exhibiting the moth-eye effect.

Non-noble metal copper nanoparticles-decorated TiO2 nanotube arrays with plasmon-enhanced photocatalytic hydrogen evolution under visible light

Cu nanoparticles (Cu NPs) were successful deposited on the TiO2 nanotube arrays (TNAs) through pulsed electrochemical deposition method. By adjusting the number of deposition cycles, the amount of Cu NPs can be controlled. Compared with pure TNAs, a new strong absorption peak appeared on Cu/TNAs under visible light region due to the surface plasmon resonance (SPR) of Cu NPs. Photoelectrochemical performance and photocatalytic hydrogen evolution characteristic of the Cu/TNAs catalysts were investigated under visible light irradiation. The novel Cu/TNAs heterogenous architectures show a stable and high photocatalytic activity for hydrogen evolution without the Pt co-catalyst.

Electron microscopy study of a Pt-Pd bimetallic structure formation on soot for catalytic systems

Bimetallic structures—Pt nanoparticles distributed on the surface of a Pd catalyst on Vulcan XC-72 soot—have been investigated. Several series of bimetallic catalysts with various contents of platinum have been obtained by pulsed electrochemical deposition. Their structure is studied using analytical high resolution transmission electron microscopy with a correction of aberrations. The data allows us to present a scheme of evolution in the bimetallic catalyst structure caused by a change in the ratio of metals Pt : Pd. For the ratio Pt : Pd = 1 : 25, the electrochemical measurements of catalytic activity have shown an extremely high current of oxygen reduction.

Carbonated hydroxyapatite deposition at physiological temperature on ordered titanium oxide nanotubes using pulsed electrochemistry

The effect of temperature and nanotubular surface morphology on calcium phosphate deposition was investigated using a modified simulated body fluid and electrochemistry. Ordered nanotubular titanium oxide plates were coated by pulsed electrochemical deposition process, while titanium oxide and pure titanium surfaces were used as controls at 80°C and 37°C. The calcium phosphate deposit was characterized using XRD, FT-IR and FE-SEM. Carbonated hydroxyapatite was deposited at the physiological temperature of 37°C on nanotubular surfaces, which provided a large surface area for hydroxide ion generation and a small volume for the confinement and concentration of hydroxide ions. Compounds containing carbonates and hydrogen phosphates were deposited on porous titanium oxide surfaces and flat titanium surfaces as the control group. This study demonstrates deposition of hydroxyapatite at physiological temperatures, which is essential for codeposition of organic bioceramics for medical use.

High performance of core–shell structured Ir@Pt/C catalyst prepared by a facile pulse electrochemical deposition

A novel core–shell structured catalyst, Ir@Pt/C, was prepared by a facile pulse electrochemical deposition approach, demonstrating several times higher mass activity towards both the anodic oxidation of methanol and the cathodic reduction of oxygen than commercial Pt/C catalyst. And the results of CO stripping revealed that the Ir@Pt/C catalyst exhibited greater ease of CO removal. The enhanced performance of the catalyst could be ascribed to the high dispersion of Pt, which led to the higher utilization of Pt, and the synergetic effect of Pt with Ir in the core–shell structure.

Electrodeposited zinc oxide arrays with the moth-eye effect

The materials of modern photovoltaic cells exhibit significant light reflection which is avoided using antireflective coatings. The possibility of fabricating antireflective coatings such as nanoscale zinc oxide arrays with a parabolic profile by pulsed electrochemical deposition from aqueous electrolytes is shown for the first time. The effect of the deposition conditions on the optical properties of oxide arrays is studied using spectrophotometry. The structural characteristics are analyzed by X-ray diffraction data. The morphology of the grown arrays is determined by atomic-force microscopy. Optimization of the pulsed electrodeposition conditions allows correction of the parabolic nanonipple sizes, thus providing the fabrication of antireflective coatings based on electrodeposited zinc oxide arrays with the moth-eye effect, applicable to photovoltaic cells.

Ultra High Performance of Core-Shell Structured Ir@Pt/C Catalyst Prepared By a Facile Pulse Electrochemical Deposition

not Available.

A pulse electrochemical deposition method to prepare membrane electrode assemblies with ultra-low anode Pt loadings through in situ construction of active core–shell nanoparticles on an electrode

Ultra-low Pt loading membrane electrode assemblies (ULP MEAs) are prepared through in situ construction of core–shell Ir@Pt nanoparticles (Ir/Vulcan XC-72R as the core) on the surface of an electrode via a pulse electrochemical deposition (PED) approach. The core material is coated on a membrane with a conventional catalyst-coated membrane process prior to the deposition of the shell metal (Pt in this case). The ULP MEAs are characterized by X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and X-ray Photoelectron Spectroscopy (XPS). The effects of a number of preparation parameters on cell performance are investigated in detail. The performance of the ULP MEA, in which the anode loadings of Pt and metals are ∼0.012 mg cm−2 and 0.044 mg cm−2(0.012 mg cm−2 Pt + 0.032 mg cm−2 Ir) respectively, is found to be competitive with that of an MEA prepared with an anode Pt loading of 0.1 mg cm−2 (commercial Pt/C catalyst from Johnson Matthey), manifesting the solid advantage of this in situ PED method.

Growth of large-scale nanotwinned Cu nanowire arrays from anodic aluminum oxide membrane by electrochemical deposition process: controllable nanotwin density and growth orientation with enhanced electrical endurance performance.

Densely nanotwinned Cu nanowire (NW) arrays with an identical diameter of ∼55 nm were fabricated by pulse electrochemical deposition at low temperature using anodic aluminum oxide as a template. Different growth orientations of nanotwinned Cu nanowire arrays were investigated. The endurance of the electrical current density before breakdown of the nanotwinned Cu NWs can reach up to 2.4 × 10(8) A cm(-2). The formation of highly dense nanotwins is attributed to relaxation of coalescence induced stress and twin fault stacking when Cu NWs grow by two-dimensional kinetics. A mechanism based on the twinning structure effect on the electromigration was proposed to explain the improved electrical endurance of Cu. The result demonstrates that the formation of nanotwins into Cu NWs can effectively suppress the void growth, leading to extended life time for use in electronic devices.