Journal Articles (before-1995)

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Subject: search.filters.subject.Electrochemical kinetics

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    The Oxygen Electrode Part 8.—Oxygen Evolution at Ruthenium Dioxide Anodes
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1977, 73 (11), 1977) Burke, Laurence D; Murphy, Oliver J; O’Neill, John F; Venkatesan, Srinivasan
    The electrocatalytic behaviour of Ti-supported RuO2, prepared by thermal decomposition of RuCl3, as substrate for oxygen evolution was investigated by a variety of techniques. B.E.T. adsorption experiments showed that the RuO2 layers are highly porous with large surface area values which, however, decrease rapidly as the annealing temperature increases above ∼ 300°C. Both the charge involved in the cyclic voltammograms and the oxygen evolution rates are dependent on the true (rather than apparent) area of these electrode surfaces, and also on the pH of the solution. The results for oxygen evolution are discussed in terms of electrochemically generated unstable surface oxides whose decomposition is catalysed by protons in acid, and hydroxide ions in base. The lower reactivity of the oxide at intermediate pH value is attributed on the one hand to loss of protons by OH groups, resulting in oxygen bridging, and on the other to lack of enhanced coordination of surface ruthenium species by OH– ions, which in this pH region are present only at low activity. The charge associated with voltammetric sweeps is accounted for in terms of surface redox processes rather than bulk penetration of protons into the oxide. The need for surface area measurements as a guide to the interpretation of the electrochemical data in the case of these oxide systems is stressed.
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    Chemical and electrochemical kinetics of CuII reduction in chloride media
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1978, 74 (08), 1978) Hibbert, D. Brynn; Sugiarto, Herman; Tseung, Alfred C. C.
    The deposition and dissolution of copper from copper sulphate solutions have been studied by galvanostatic measurements. From current overpotential relations it is concluded that the rate limiting step in the electrochemical reduction or oxidation at pH 1 is the reaction Cu2++ e ⇌ Cu+. In the presence of chloride and sulphite ions, the CuCl–2 complex is formed which stabilises the CuI state. The rate limiting step is now the reduction of this complex. Anodically the slow step is the oxidation of CuCl–2. The addition of sulphite ions chemically reduces CuII to CuI, but the rate is much slower than the electrochemical reduction at an overpotential of –100 mV. At pH 1 chemical dissolution of the copper deposited at the cathode occurs.