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Oxide electrocatalysts for the oxygen evolution reaction. Improvements of IrO2-based coatings

By Ch. Urgeghe, M.M. Borgato, A. Morozov, S. Ferro and A. De Battisti


In consideration of the high cost of noble-metal-based electrode materials, the research of new compositions is mainly focused on the obtainment of long service-life anodes, at low noble-metal concentrations in the coating (e.g., 0.5÷1.0 g Ir m-2).\ud The result of our research has already led to the preparation of an IrO2-based anode (3 g Ir m-2), which has a service life of one year in dilute Na2SO4 solutions, under a current density of 2000 A m-2. The well known alternative would be IrO2-Ta2O5 coating, with a comparatively higher iridium content (10 g m-2).\ud The factors that allowed improved performance for our electrode may be schematized in the following points:\ud • Coating composition. The maximum stability has been reached with mixed-oxide coatings based on IrO2 and SnO2. Precursor solution compositions were devised, avoiding the problem of tin precursor volatilization.\ud • An original pre-treatment of the titanium support surfaces has been worked out, affording them the necessary chemical and electrochemical properties. Further advantages of the above solution are the environment-friendly and avoids acidic wastes.\ud • An optimal structure of stabilizing interlayer has been achieved, taking into consideration the anode wearing processes.\ud • Proposals and rules have been elaborated for the technology of electrode coatings stable under oxygen evolution.\ud Anodes prepared following the above know-how are in use in electrochemical devices for tap-water cleaning, sterilization of water in hospital environments and more generally in medical applications, chlorine-free sterilization of swimming pools.\ud Additionally, an interesting application is the preparation of electrodes for pacemaker devices, requiring besides bio-compatibility and durability, also a capacity of the order of 10 mF cm-2 at 100 Hz. Perspectives in cathodic protection and in industrial processes, where PbO2-based electrodes are traditionally used, must also be considered

Publisher: Società Chimica Italiana
Year: 2002
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