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Abstract In this study, a novel flexible electrode consisting of homogeneous RuO 2 nanoparticles (NPs) wrapped around the carbon fiber cloth (CC) is fabricated by combining the cathodic electro-deposition in the aqueous acidic RuCl 3 ·xH 2 O solution and annealing in air atmosphere. The as-fabricated RuO 2 NPs/CC electrode with electro-deposition duration of 10 min demonstrates a superior electrocatalytic activity with a lower overpotential of ca. 1.05 V vs. SCE and its current density reaches up to 175 mA cm−2 at 1.2 V vs. SCE for chlorine evolution reaction (CER) in 5.0 M NaCl aqueous solution, outperforming many of the reported counterparts. The as-revealed outstanding electrocatalytic activity should be attributed to several beneficial factors such as its typical integrated binder-free 3D architecture, higher usage efficiency of active RuO 2 NPs, greatly decreased interfacial resistance, etc. This work paves a way to utilize the carbon fiber cloth decorated with active noble metal oxides for boosting electrochemical Cl 2 production. [ABSTRACT FROM AUTHOR]

Controllable morphology of polypyrrole wrapped graphene hydrogel composites in nano scale has been successfully developed via in-situ electrochemical co-deposition in an aqueous solution containing pyrrole monomers (Py), graphene hydrogel (GH) and surfactant. The presence of different surfactants (sodium dodecylbenzenesulfonate (SDBS) or poly (sodium 4-styrenesulfonate) (PSS)) in electrolyte plays an important role in structural, morphological and supercapacitive properties of polypyrrole/graphene hydrogel (PPy/GH) composite films. Scanning electron microscope analysis demonstrated that the unique design of PPy/GH-PSS morphology is not only to control micro/nanostructure of PPy wrapped GH, but also to develop the nanostructure morphology of PPy matrix. A large surface area of GH-PSS with the preserving decent electronic conductivity of PPy/GH-PSS composite expected to support the facile ionic transport is investigated. The results revealed that these features endow PPy/GH-PSS composite film electrode with the excellent electrochemical properties such as the high specific capacitance of 640.8 F g −1 at 1 A g −1 and energy density of 68.2 W h kg −1 at a power density of 438.5 W kg −1 , suggesting of its extensive potential application for the flexible thin film supercapacitors. [ABSTRACT FROM AUTHOR]

Non-precious metal electrodes, Ni and Co hydroxides and oxides, have been recently found active towards electro-oxidation of methanol in alkaline. In this article, we present a first and complete study on composition dependence of Ni–Co hydroxides and oxides for methanol electro-oxidation. Ni–Co hydroxide electrodes were prepared by co-electrodeposition on stainless steel mesh (SSM). The atomic ratio of Ni/Ni + Co in Ni–Co hydroxides was controlled by adjusting the ratio of precursor concentration. Ni–Co oxide electrodes were further obtained by annealing the Ni–Co hydroxides. The morphology factors of Ni–Co hydroxides and oxides were revealed by measuring double layer capacitance using cyclic voltammetry (CV). Methanol oxidation reaction (MOR) performance of these Ni–Co hydroxides and oxide electrodes was investigated by CV, and electrochemical impedance spectroscopy (EIS) techniques at room temperature (RT, ∼25 °C). It is found that the MOR performance of Ni–Co hydroxides increased with the increase of Ni content, while the performance of Ni–Co oxide electrodes presented a volcano plot. The highest MOR performance, the smallest charge transfer resistance and Tafel slope were found at the atomic composition of 46% Ni. Such an enhancement probably was due to the synergistic effect of co-existing Ni and Co in the spinel structure. In contrast, the electrode with the mixture of Ni oxide and Co oxide was unable to reach such a high activity. The function of Ni in Ni–Co hydroxides and oxides was attributed to facilitating the methanol oxidation, and in low potential it presented high absorption of intermediate products. [ABSTRACT FROM AUTHOR]

In this study, Pt-Pd alloy catalyst was fabricated on carbon papers via electro-deposition as an alternative catalyst for oxygen reduction in air-cathode Microbial Fuel Cells (MFCs). Effects of electro-deposition cycles and supporting materials (graphene and carbon nanotubes (CNTs)) on oxygen reduction reaction (ORR) activity of the Pt-Pd electrode and power generation in MFCs were investigated. The structural and electrochemical properties of the Pt-Pd catalyst were characterized by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). Results showed that the Pt-Pd electrode showed a good ORR activity. A MFC with a Pt-Pd cathode of 15 deposition cycles produced a maximum power density of 1274 mWm −2 , comparable to that with a conventional Pt/C cathode (0.5 mg Pt cm −2 ). CNT as the supporting material further increased ORR activity of the Pt-Pd electrode and power generation capacity in MFCs, while graphene as the supporting material did not produce positive effects. XRD results confirmed the presence of Pt/Pd elements on the electrode. SEM results showed that decoration using CNT reduced Pt-Pd particle size and promoted them even dispersion on the carbon paper. The Pt-Pd electrode attained a comparable performance to the Pt/C electrode when controlling an optimum deposition cycles and using CNT as the supporting materials, which demonstrates the potential of replacing Pt as an oxygen reduction catalyst in MFCs due to high oxygen reduction activity and relatively low cost. [ABSTRACT FROM AUTHOR]

This paper demonstrated an electrochemical sensor based on NiO nanoparticles-graphene composite film (NiO/GR) modified glassy carbon electrode for detecting ascorbic acid (AA) in the presence of folic acid using differential pulse voltammetry. The obtained NiO/GR nanocomposite was fabricated by electro-deposition technology. The morphologies and interface properties of NiO/GR composite film were examined by scanning electron microscopy, energy dispersive X-ray spectroscopy and electrochemical impedance spectroscopy. The modified electrode exhibits excellent sensing performance for detecting AA with linear range from 0.05 to 1100 μM and a detection limit of 0.0167 μM (S/N = 3). Under optimal conditions, the sensor displays excellent stability and satisfactory results in real samples analysis. [ABSTRACT FROM AUTHOR]

The growth of the first Pd layers electrochemically deposited in a chloride containing solution onto Au(111) has been investigated by cyclic voltammetry, potential step experiments and time resolved in situ surface X-ray diffraction. The underpotential deposition of the first layer is depicted by several processes with different kinetics. A first reaction, characterized by a quite fast kinetics below 1 s, is followed by a slow adsorption process and by instantaneous nucleationand- growth. The almost complete layer-by-layer growth up to two pseudomorphic layers has been observed, even if the third and following relaxed layers start growing before the full completion of the second one, forming huge 3D islands. Chloride does not seem to act as a smoothing agent during the Pd film deposition. Finally, thanks to the detailed structure of the Pd deposit obtained with in situ surface X-ray diffraction we could unambiguously assign the peaks observed in the electrochemical characterization of the Pd/Au(111) films in 0.1 M H2SO4. [ABSTRACT FROM AUTHOR]

Abstract: SnO2, as an undercoat, has been recently applied on Ti substrate to prepare PbO2 anodes to improve the stability and electro-catalytic activity. In this work, we explored the electro-deposition of PbO2 on the Ti substrate with a Sb-doped SnO2 undercoat, from a traditional acidic nitrate solution. The morphology and microstructure of the PbO2 coatings were investigated by varying electro-deposition temperature and time. It is found that the Sb-doped SnO2 undercoat significantly promotes the electro-deposition process of PbO2. At a low electro-deposition temperature, a preferential crystallographic orientation is usually observed in the coatings, which exhibit a caterpillar-like morphology. At a higher deposition temperature, the PbO2 coatings display a more tightly packed pyramid-like morphology. The crystallite size increases with deposition temperature. Electrochemical performance of the deposited PbO2 largely depends on their morphologies and microstructures. It is suggested that deep reaction path, high porosity and good connectivity between crystallites play a synergic role in determining the electrochemical performance of the PbO2 coatings. [Copyright &y& Elsevier]

Abstract: In most electrochemical processes as in continuous electro-deposition, mass transfer is governed by the near-wall hydrodynamics of the bath. The turbulent regime enhances significantly the mixing and consecutively the process itself. The situation examined here is that of a binary turbulent electrolyte flowing between two parallel electrodes. We simulate via direct numerical simulations (DNS) the behavior of the flow field, concentration and electrical potential. These three physics are linked by the Butler–Volmer boundary condition which acts at the electrode/electrolyte interface. Resolving the full problem represents a challenging task from a numerical point of view. We present the numerical methodology used in this work and all the quantitative results obtained. We also point at significant differences with the past published results, in particular on the mass transfer statistics, which tend to confirm that the fully coupled approach is necessary to obtain a fine and reliable description of the physic involved in such electrochemical transformations. [Copyright &y& Elsevier]

Abstract: The work comprises results of the studies on the mechanism and kinetics of hexaamminecobalt(III) reduction in ammonia-chloride solutions at pH 9.5. The studies were preceded by the thermodynamic analysis of the electrolyte. Electrolyte stability was determined by UV–vis absorbance measurements. Electrochemical examinations were performed by applying cyclic voltammetry (CV) combined with Electrochemical Quartz Crystal Microbalance (EQCM) as well as with spectrophotometric measurements. The results indicated that reduction process of [Co(NH3)6]3+ consists of two steps. In the first step [Co(NH3)6]3+ is reduced to [Co(NH3)4]2+ and [Co(NH3)5]2+, and then ammonium complexes of Co2+ are reduced to Co0. Deposition of Co takes place only in the overpotential deposition range. Values of electrochemical equivalents M/z within this range indicate formation of Co(OH)2 phase. The examined reactions are diffusion controlled. Diffusion coefficients of complexes participating in particular reactions were determined with the use of Randles–Sevcik and Berzins–Delahay equations. In anodic part M/z values indicate 2-electrons reaction of cobalt oxidation connected with chemical dissolution of cobalt hydroxide formed during cathodic sweep. [Copyright &y& Elsevier]

Abstract: We report the preparation of Dimensionally Stable Anode® coatings with a special surface morphology, which is tailored for the chlorine gas evolution. A simple electro-deposition route is applied to create coatings with large crack sizes and three-dimensionally arranged catalyst spheres on top of the coating surface. This morphology shows an increase of the specific outer electro-catalyst surface area, which is the main working part during intensive chlorine gas evolution. By this means, a decrease of the chlorine overpotential and simultaneously a reduction of the noble metal content can be achieved, which is favorable in terms of energy and resource efficiency of the chlor-alkali industry. The influence of the deposition parameters on phase structure, phase composition, surface morphology and electrochemical properties were investigated using XRD, ICP-OES, SEM, CV and polarization techniques. [Copyright &y& Elsevier]

Abstract: A novel ECR-modified electrode is fabricated by electrodeposition of Eriochrome Cyanine R (ECR) at a glassy carbon (GC) electrode by cyclic voltammetry (CV) in double-distilled water. The characterization of the ECR film modified electrode is carried out by atomic force microscopy (AFM), infrared spectra (IR), spectroelectrochemistry and cyclic voltammetry. The results show that a slightly heterogeneous film formed on the surface of the modified electrode, and the calculated surface concentration of ECR is 2×10−10 mol/cm−2. The ECR film modified GC electrode shows excellent electrocatalytic activities toward the oxidation of serotonin (5-HT) and norepinephrine (NE). Furthermore, the modified electrode can separately detect 5-HT and NE, even in the presence of 200-fold concentration of ascorbic acid (AA) and 25-fold concentration of uric acid (UA). Using differential pulse voltammetry (DPV), the peak currents of 5-HT and NE recorded in pH 7 solution are linearly dependent on their concentrations in the range of 0.05–5μM and 2–50μM, respectively. The limits of detection are 0.05 and 1.5μM for 5-HT and NE, respectively. The ECR film modified electrode can be stored stable for at least 1 week in 0.05M PBS (pH 7) at 4°C in a refrigerator. Owing to its excellent selectivity and sensitivity, the modified electrode could provide a promising tool for the simultaneous determination of 5-HT and NE in complex biosamples. [Copyright &y& Elsevier]

Abstract: Composite films of carbon nanotubes (CNTs) with polyaniline (PANI), polypyrrole (PPY) or poly[3,4-ethylenedioxythiophene] (PEDOT) were prepared via electrochemical co-deposition from solutions containing acid treated CNTs and the corresponding monomer. In the cases of PPY and PEDOT, CNTs served as the charge carriers during electro-deposition, and also acted as both the backbone of a three-dimensional micro- and nano-porous structure and the effective charge-balancing dopant within the polymer. All the composites showed improved mechanical integrity, higher electronic and ionic conductivity (even when the polymer was reduced), and exhibited larger electrode specific capacitance than the polymer alone. Under similar conditions, the capacitance was enhanced significantly in as-prepared PPY-CNT and PEDOT-CNT films. However, the fresh PANI-CNT film was electrochemically similar to PANI, but PPY-CNT and PEDOT-CNT differed noticeably from the respective polymers alone. In continuous potential cycling tests, unlike the pure polymer and other composite films, PANI-CNT performed much better in retaining the capacitance of the as-prepared film, and the possible cause is analysed. [Copyright &y& Elsevier]

Abstract: The paper describes the results of treatment of soil samples, deriving from a dismissed industrial site, contaminated with several metals: Hg, Ni, Co, Zn, Pb, Cu, Cr, As and organic substances. The soil was subjected to remediation based on a process in which an oxidising leaching agent was produced electrochemically in-line in an undivided electrochemical cell reactor equipped with a Ti/Pt-Ir anode and a stainless steel cathode. Leaching of the soil samples was performed under dynamic conditions using a leaching column. A subsequent regeneration of the leaching solution, which consisted in electrodeposition of metals and electro-oxidation of organic substances, was carried out in a packed-bed reactor equipped with a centrally positioned graphite rod, serving as an anode, and stainless steel three-dimensional filling as a cathode. The study was focused on how and to which extent the metals present in the soil, as organic complexes, can be solubilised and how the process rates are impacted by the solution pH and other process variables. Data obtained under non-oxidising conditions, typically adopted for leaching of metals, are compared with the performance of chlorine-enriched leaching solutions. The results obtained under various conditions are also discussed in terms of the total organic carbon (TOC) removal from the water phase. [Copyright &y& Elsevier]

Abstract: Our recent study on a challenge of new materials for next generation''s magnetic recording approaching an ultra high areal recording density beyond 1Tbit/in.2 is overviewed. We proposed novel methods for fabricating high performance magnetic recording heads and media by making the best use of wet (electro- and electroless-deposition) and dry (sputtering) processes. We believe that these results contribute significantly to the progress in magnetic recording and constitute a breakthrough for materializing an unexplored areal recording density beyond 1Tbit/in.2. [Copyright &y& Elsevier]