Thermal Decomposition Of RuCl3 Research Articles

The Effect of Ruthenium on the Corrosion of Stainless Steel in Nitric Acid Liquors

Nuclear reprocessing plant liquors resulting from the PUREX process contain ruthenium present as a mixture of nitrosyl complexes in nitric acid. Ruthenium is not corrosive toward stainless steels unless the conditions are sufficiently oxidizing to promote the decomposition of one or more of the nitrosyl complexes present, in which case the production of finely-divided RuO2occurs. In this work, the corrosive effect of RuO2coatings that were produced by the thermal decomposition of RuCl3is reported. The corrosion potential and corrosion rate of stainless steel were found to be significantly increased by the presence of RuO2coatings, and depended on the temperature, but did not depend on the amount of RuO2present provided above a threshold which was found to lie in the range 43 μg/cm2to 86 μg/cm2of RuO2. Corrosion potential measurements indicated that in hot 10 M nitric acid, the RuO2coatings formed by the thermal decomposition of RuCl3reproduced the effect of RuO2formed from the in situ oxidation of a tri-nitrato ruthenium compound. However, a stronger, but only short-term, effect was also found, which is attributed to an intermediate precursor of RuO2, considered likely to be RuO4. Two separate corrosion accelerating effects can therefore arise in ruthenium-bearing liquors.

Comparison of Pyrochlore and Perovskite Electrodes Towards the Oxygen Evolution in Alkaline Media

The identification of economically feasible and high efficient materials towards the oxygen evolution (OER) and reduction (ORR) reactions in alkaline media will constitute a major advancement in a variety of technologies such as water splitting, elctrowinning, fuel cells and metal-air batteries. OER and ORR have proven to be catalytic dependent electrochemical processes, and thus, the catalytic material at the oxygen electrode plays an important role in the performance of such technologies. Numerous research studies have been carried out on the synthesis of new electrode materials in order to reduce the voltage loss associated with the oxygen reactions. In the present work, a comparison of OER behavior of a group of pyrochlore materials (A2B2O7-δ), and non-noble transition metal perovskites (ABO3) will be presented. The pyrochlore and perovskite structures were synthesized by a facile two-step combustion method yielding high purity phases with crystallite size in the vicinity of 20nm. The synthesized compounds include La1-xCaxFeO3, Pb2Ru2O7, and their substitutions, compared to un-supported RuO2 prepared by thermal decomposition of RuCl3. The catalysts powders were dispersed on a Nafion containing solution to form a catalyst ink [1]. The samples were tested in alkaline media in a traditional three-electrode system under continuous N2purging. Among the characteristics that make pyrochlores attractive for oxygen electrodes, is the unusual framework containing high density of oxygen vacancies and their apparent ordering which is believed to aid in the oxygen anion mobility [2]. Perovskite materials are attractive due to the wide range of substituting elements that can be employed to tune their electrocatalytic properties. All the samples were characterized by XRD for phase analysis, XPS for valency, SEM for surface morphology. The OER electrochemical performance has been investigated by means of steady state current measurements. XRD spectra of selected samples and the OER activity are presented in Figure 1a and 1b, respectively. The effect of dopant concentration on the oxygen evolution activity will be discussed. Acknowledgements This work is supported by the IGERT-NSF fellowship and partially funded by the US Department of Energy/NETL, Oak Ridge Institute for Science and Education (ORISE) fellowship.

Surface modification of RuO2 electrodes by laser irradiation and ion implantation: Evidence of electrocatalytic effects

RuO2 thin layers were deposited on Ti supports by thermal decomposition of RuCl3 at 400°C. Some of the samples were subjected to laser irradiation between 0·5 and 1·5 J cm−2. Some others to Kr bombardment with doses between 1015 and 1016 cm−2. Modifications introduced by the surface treatments were monitored by cyclic voltammetry and O2 evolution in H2SO4 solution. The voltammetric charge increased with surface treatment almost to the same extent for irradiation and bombardment. The electrocatalytic activity turned out much higher for Kr bombarded samples. Raw experimental data were scrutinized in an attempt to separate geometric from electronic factors. True electrocatalytic effects are clearly seen to prevail over purely surface area effects.

ChemInform Abstract: Anodic TiO2 Thin Films. Photoelectrochemical, Electrochemical, and Structural Study of Heat‐Treated and RuO2 Modified Films.

AbstractRuO2 films of nominal one monolayer thickness are deposited by thermal decomposition of RuCl3 on anodically grown polycrystalline TiO2 (rutile) films.

Colloid-chemical properties of ruthenium dioxide in relation to catalysis of the photochemical generation of hydrogen

A colloid of RuO2, prepared by thermal decomposition of RuCl3, was characterized with respect to its colloid-chemical properties and assessed as a catalyst for photochemical production of hydrogen. The RuO2 proved to be unstable towards coagulation, even under conditions of low electrolyte concentration and in the presence of polymers. The sol manifested the same electric double layer characteristics as many other oxide dispersions. The point of zero charge (p.z.c.) in indifferent electrolyte was positioned at pH 5.75.

Hydrogen detection in ruthenium oxide layers by means of the 1H(15N,αγ)12C nuclear reaction

Hydrogen in RuOx layers on quartz prepared by the thermal decomposition of RuCl3 has been detected by means of a nuclear technique. RuOx absorbs water rapidly from the liquid and a constant H/Ru ratio is found throughout the thickness of the layer. RuOx also absorbs water from the ambient moisture, but no saturation is observed even after several months. The permeability of RuOx to water is explained in terms of grain boundary diffusion.

ChemInform Abstract: THE OXYGEN ELECTRODE. PART 8. OXYGEN EVOLUTION AT RUTHENIUM DIOXIDE ANODES

AbstractRuO2‐Elektroden werden durch thermische Zersetzung (bei 350°C) von RuC13‐Über‐ Zügen auf Ti‐Draht an der Luft hergestellt und auf ihre Eignung zur Verwendung als Anoden für die O,‐Entwicklung durch Elektrolyse wäßriger saurer und alkalischer Lösungen hin untersucht.

The oxygen electrode. Part 8.—Oxygen evolution at ruthenium dioxide anodes

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.

Ruthenium dioxide: a new electrode material. II. Non-stoichiometry and energetics of electrode reactions in acid solutions

RuO2 films on Ta and Pt as supports have been prepared by thermal decomposition of RuCl3 at different temperatures in various atmospheres. Bulk and surface electronic properties of these films have been deduced from their behaviour as electrodes with respect to reactions involving or not involving the adsorption of reactants and/or products, (for example Fe2+/Fe3+, I−/I2, H2/H+ and some simple organic reactions). Results indicate that the non-stoichiometry of the oxide film is a function of the temperature of preparation and also of the atmosphere of annealing. In particular, smaller fractions of Ru3+are obtained as the temperature of preparation is increased and/or the atmosphere of annealing is made more oxygenated. Kinetics of electrode reactions suggest an essentially metallic nature for RuO2 films. They behave very well with redox systems but exhibit poor electrocatalytic features in that rates of reactions involving adsorption steps are usually lower on RuO2 films than on noble metals. Possible reasons for this are discussed in detail.

Ruthenium dioxide: a new electrode material. I. Behaviour in acid solutions of inert electrolytes

The electrochemical behaviour of RuO2 film electrodes, prepared by the thermal decomposition of Ru Cl3 on metallic supports has been investigated in solutions of inert electrolytes. Steady-state pot entiostatici/E curves, cyclic voltammetry and charging curves are presented. The procedure for the preparation of electrodes is described.