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Heterostructured Pd-Pt core-shell nanocubes (NCs) are shown to display catalytic activity in the glucose oxidation reaction (GOR), and were employed as non-enzymatic glucose sensors in 0.1 M NaOH solution. High-angle annular dark-field transmission electron microscopy and line-scanned energy-dispersive X-ray spectroscopy analyses show that the growth of the Pt shell initially occurs via a layer-by-layer mode, but then switches to the island mode. The voids formed between Pt islands contribute to an increase in the electrochemically active surface area. Based on the same catalyst loading mass, the results of Tafel measurements and cyclic voltammetry indicate that the heterostructured Pd-Pt core-shell NCs (typically 32.7 nm in size) display an exchange current density of 1.81 × 10 mA cm for chemisorption and dehydrogenation of glucose at the onset of the GOR, and an activity of 0.322 mA in the subsequent reaction that causes the formation gluconolactone on the Pt-OH surface. These values are larger than those observed for 7.5-nm Pt nanoparticles (1.51 × 10 mA cm and 0.187 mA cm, respectively). Additionally, the core-shell NCs exhibit a sensitivity of 170 μA∙mM∙cm under GOR catalysis conditions, require a potential as low as −0.05 V (vs. Ag/AgCl) which favors selectivity, and have a linear response range that extends from 0.3 to 6.8 mM. The potential of these NCs for use in non-enzymatic sensing of glucose is further exemplified by a successful analysis of spiked calf serum. In our perception, this sensor also has a large potential in glucose fuel cells. [ABSTRACT FROM AUTHOR]

Electrochromic devices are fabricated by using polyaniline (PANI) doped with poly(styrene sulfonic acid) (PSS) as coloring electrodes, poly(ethylenedioxythiophene)-poly(styrene sulfonic acid) (PEDOT-PSS) as complementary electrodes, and hybrid polymer electrolytes as gel electrolytes. The device based on LiClO4-based electrolyte (weight ratio of PMMA:PC:LiClO4 = 0.7:1.1:0.3) shows the highest optical contrast and coloration efficiency (333 cm2/C) after 1200 cycles in these devices, and the color changes from pale yellow (−0.5 V) to dark blue (+2.5 V). The spectroelectrochemical and electrochromic switching properties of electrochromic devices are investigated, the maximum optical contrast (Δ T%) of electrochromic device for ITO|PANI-PSS|PMMA-PC-LiClO4-SiO2|PEDOT-PSS|ITO are 31.5% at 640 nm, and electrochromic device based on LiClO4-based electrolyte with SiO2 shows faster response time than that based on LiClO4-based electrolyte without SiO2. [ABSTRACT FROM AUTHOR]

Dispersions of Pd-NiO nanoparticles were electrochemically synthesized in a water-in-oil microemulsion, with fine control by appropriate adjustment of the concentration ratio of H2O to surfactant. The feasibility of using these Pd-NiO nanoparticles as a new activator for electroless Ni deposition (END) was examined. In this study, fast electroless deposition was achieved using Pd-NiO nanoparticles as a catalyst. A systematic study of the deposition kinetics and the mass activity by electrochemical quartz-crystal microgravimetry indicated that adding NiO to active colloids can shorten the induction time, and that reducing the particle diameter can accelerate END reactions because steady-state deposition is achieved more quickly. [ABSTRACT FROM AUTHOR]

Abstract: The preparation of RuO2–Ta2O5/Ti electrodes, by dip-coating, for use in supercapacitors was investigated. The stability and specific capacitance of the electrodes annealed at various temperatures was examined. The results show that highly stable electrodes with a specific capacitance of 170FgRuO2 −1 were obtained at approximately 250°C, while electrodes with a lower capacitance (130FgRuO2 −1) were obtained at 300°C. The annealing time needed to obtain a stable RuO2–Ta2O5/Ti electrode at various temperatures correlates well with the Arrhenius’ law: with the activation energy (E) of the annealing reactions for the electrodes being estimated as 73.5kJmol−1. SEM images of the electrodes show the coating films to have rough surface morphology with cracks 2–6μm in width. XRD data indicate that the coating films obtained are composed of crystalline RuO2 and amorphous tantalum oxide. [ABSTRACT FROM AUTHOR]

Abstract: The determination of the iodine adsorption number (IN) of carbon black (CB) by using a direct electrochemical reduction method was investigated. The results show that the IN measured by the electrochemical method is close to that obtained by traditional titration methods. A low relative standard deviation (RSD) of ca. 4–5%, for the IN values, shows the high precision of the measurements, while material balance calculation for the iodine in the measurement system confirmed the accuracy of the IN values. These results demonstrate the feasibility and reliability of the direct cathodic reduction method as an analytical method for IN. [ABSTRACT FROM AUTHOR]

Abstract: Hydrothermal treatment (HTT) of RuO2–Ta2O5/Ti electrode, as a method for improving their performance, for use in supercapacitors was investigated. The results show that HTT significantly enhances the stability of the electrodes. The specific capacitance of electrodes, subject to HTT in the temperature range 180–250°C remains unchanged after 1000 CV cycles between −0.2 and 1.1V vs. SCE; without HTT a decay to 97% of the initial is observed. The results also show that HTT decreases the activity of the electrodes for O2 and H2 evolution and increases the voltage window by 56–135mV for supercapacitors, but with a specific capacitance decrease of 7–27%. XPS analyses show the existence of more hydroxides after the HTT, which leads to a little increase in the interplanar distance as indicated in the XDR results. Contact angle measurements show the presence of a more hydrophilic surface after HTT. [Copyright &y& Elsevier]

Abstract: The co-eletrodeposition of Pt–Ru on carbon electrodes was carried out using a double-potential pulse method in electrolytes containing varying concentrations of RuCl3 +H2PtCl6 in an attempt to deposit highly dispersed Pt–Ru electrocatalyst with a controlled composition. The amounts of the Pt and Ru deposited on the electrodes were analyzed using an inductively coupled plasma atomic emission spectrometer (ICP-AES). The results revealed that the Pt loading on the substrates increases linearly with H2PtCl6 concentrations in the bath while the Ru loading is not related to the concentration of RuCl3, indicating that the reduction of Pt ions is the dominant reaction in the cathodic deposition of Pt–Ru clusters on the substrate. The Pt–Ru/C electrodes were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The optimum Ru content in the deposited Pt–Ru electrode for promoting the electro-oxidation of MeOH and adsorbed CO was found to be 25atm%, by CO-stripping measurements in 0.5M H2SO4 and by cyclic voltammography in a solution comprising CH3OH (2.0M) +0.5M H2SO4 (0.5M). SEM results showed that the generation of nucleation sites and growth of the deposits progresses continuously on carbon substrate and already deposited Pt–Ru particles. The particle size and loading amount of the deposits was found to increase with an increase in the number of cycles of the repeating double-potential pulse. [Copyright &y& Elsevier]

Abstract: Anodic, cathodic and cyclic voltammetric (CV) deposition of ruthenium oxides from aqueous RuCl3 solutions have been investigated using stationary and rotating disk electrodes (RDE) in this work. The CV deposition behavior was examined using a RDE to differentiate the contribution of current from the reactions of ruthenium ions in the electrolyte and ruthenium oxides already adsorbed on the electrode. The results indicate that the CV growth of ruthenium oxides within the potential range of aqueous electrolyte decomposition is attributed to the anodic oxidation of ruthenium ions in the electrolyte. Cathodic deposition occurs only at potential negative than −0.30V versus saturated calomel electrode (SCE) when H2 evolves on the electrodes. Anodic deposition of ruthenium oxides can be obtained effectively in the potential range of ca. 0.9–1.1V versus SCE, depending on the pH value of the electrolyte. The optimum anodic and cathodic deposition potential for maximum deposition efficiency is 1.0 and −0.9V versus SCE, respectively, in the electrolyte solution of pH 2. [Copyright &y& Elsevier]

1,10-Phenanthroline (phen) can be successfully used as an accelerator for Ag-catalysed electroless copper deposition (ECD) processes. Electrochemical quartz crystal microbalance analyses indicate that the mass activity in terms of thickness of deposited Cu layer and average ECD rate within a deposition time of 110 s for Ag nanoparticles activated by phen are 7.86 × 10 -3 μm μg -1 and 1.43 × 10 -4 μm μg -1 s -1 , respectively, whereas Ag nanoparticles without phen cannot catalyse the reaction. Furthermore, Tafel and cyclic voltammetric results show that the addition of phen to the ECD bath significantly enhances the ability of the Ag nanoparticles to catalyse the oxidation of HCHO and suppresses the formation of CuO. [ABSTRACT FROM AUTHOR]