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Defective Pd@Pd-Pt nanocubes (NCs) were successfully synthesized by a displacement deposition method. In this study, a Pt layer was predominantly deposited at the corners and edges of Pd NCs to form concave NC surfaces and a Pd-Pt shell with a Pd-only core. Additionally, rotating ring-disk electrode experiments were performed to determine the mass activities of these Pd@Pd-Pt NCs, which acted as oxygen reduction catalysts in a KOH solution. The concave Pd@Pd-Pt NCs (28.2 nm) exhibited a 1.7-fold higher activity than that of 7 nm Pt nanoparticles. After accelerated durability tests, the data indicated the prepared NCs retained nearly 80% of the initial activity for the oxygen reduction reaction. [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: 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]

Poly(6-cyanoindole) (P(CnId)) is blended with poly(styrenesulfonic acid) via doping periods of 1, 10, 20, and 30 s to obtain P(CnId)–1PSS, P(CnId)–10PSS, P(CnId)–20PSS, and P(CnId)–30PSS electrodes, respectively. FT-IR studies have revealed that P(CnId) is doped with PSS. Pt particles can be doped into P(CnId)–1PSS, P(CnId)–10PSS, P(CnId)–20PSS, and P(CnId)–30PSS by chronocoulometry (0.15 C) using electrodeposition to acquire P(CnId)–1PSS–Pt, P(CnId)–10PSS–Pt, P(CnId)–20PSS–Pt, and P(CnId)–30PSS–Pt films, respectively. For comparative purposes, in this study, Pt particles were deposited into P(CnId) under the same conditions. Scanning electron microscopy (SEM) characterization revealed that platinum distributes more uniformly into the as-prepared P(CnId)–10PSS films. The anodic peak currents could be clearly observed to reach the saturation point at a methanol concentration larger than 0.8 M. A large electrocatalytic current towards methanol oxidation (27 mA cm−2 mg−1) was noticed in P(CnId)–10PSS–Pt electrodes in comparison to P(CnId)–Pt without PSS (6.3 mA cm−2 mg−1) at +0.86 V (vs. RHE), indicating that the P(CnId)–10PSS–Pt electrode reveals potential applicability as an electrocatalyst support. • A cyanoindole-based polymer (P(CnId)) was synthesized using electrochemical polymerization. • P(CnId)/PSS electrodes were fabricated using different PSS doping periods. • P(CnId)–10PSS–Pt electrode attains the largest electroactive area for H 2 desorption/adsorption. • P(CnId)–10PSS–Pt electrode reveals high electrocatalytic current towards methanol oxidation. • P(CnId)–10PSS–Pt composite is useful for developing promising catalysts in DMFCs. [ABSTRACT FROM AUTHOR]

Abstract: Fine spherical mesocarbon-microbeads (MCMBs), having average particle sizes of 24.57, 11.69 and 10.74μm, were mixed with various amounts of solid-resins (with high β-resin contents) to prepare graphite-matrixes in self-sintering reactions. The results indicate that the self-sintering reactions of the MCMBs can be significantly improved by enhancing the contacting-pattern of the mixture. MCMBs with smaller particle sizes favor self-sintering reactions and can be used to form high-quality graphite-matrixes. In addition, the self-sintering reactions are strongly dependent on the β-resin content of the raw materials. The bending strength of the graphite-matrixes increases, while the density of the graphite-matrixes decreases, with an increase of the β-resin content in the raw materials. The optimum β-resin content in the mixtures needed to obtain high density graphite-matrixes is approximately 5.0wt.%. [Copyright &y& Elsevier]