Mixtures of IrO 2 '/MnO 2 (30:70 mol%) have been electrochemically studied by cyclic voltammetry (CV) in acid solution. The crystalline structure, morphology and the electrochemical properties of the electrodes have been studied as a function of the annealing temperature. X-ray diffraction analysis (XRD), show absence of Mn 2 O 3 phase formation and suggest the possible of formation of a solid solution of IrO 2 and MnO 2 mainly between 400 and 450 8C. The voltammetric behavior depends on the potential cycle number and annealing temperature employed in the preparation of the oxide layer. A good potential window in aqueous H 2 SO 4 and high electroactive area are obtained due to the contribution of Ir redox transitions. Energy-dispersive X-ray (EDX) and scanning electron microscopy (SEM) analysis suggest an enrichment of the Ir content on the surface at the cost of the dissolution of the manganese present in the film when the electrode is submitted to the continuous potential scan. The electrodes have been found to perform well in electrochemical capacitor applications with a specific capacitance close to 550 F g (1. The large capacitance exhibited by this system arises from a combination of the double-layer capacitance and pseudocapacitance associated with surface redox-type reactions.

Surface characterization of Ir-based Ti-and Sn-containing electrodes of nominal composition, Ir03Ti(07)SnO2 (0 x 0.7), was performed ex situ by scanning electron microscopy and energy-dispersive x-ray and n situ by open-circuit potential measurements and cyclic voltammetry. Despite the use of SnCl2 as precursor, energy-dispersive x-ray results showed the real composition to be very distinct from nominal due to SnCl4 volatilization during the calcination step in the electrode preparation procedure. SnCl4 formation in the precursor mixture was confirmed by visible spectrophotometric measurements. The substitution of Ti02 by 5n02 results in a significant increase in electrochemically active surface area, as supported by scanning electron microscopy, anodic voltammetric charge, q, and the double-layer capacity, Cdl, as a function of composition. Roughness factors between 3600 and 5100 were obtained. A linear Cdl vs. qagraph with an angular coefficient close to one was obtained. InfroductionFew electrode materials can withstand such adverse conditions as high anodic potentials combined with aggressive chemical conditions (e.g., elevated acidity of medium, chlorine, etc). Among these materials are ther-ABSTRACT Surface characterization of Jr-based Ti-and Sn-containing electrodes of nominal composition, Jr0 3Ti(O 7)Sn0S (0 x 0.7), was performed ex situ by scanning electron microscopy and energy-dispersive x-ray and in situ by open-circuit potential measurements and cyclic voltammetry. Despite the use of SnC12 as precursor; energy-dispersive x-ray results showed the real composition to be very distinct from nominal due to SnCl4 volatilization during the calcination step in the electrode preparation procedure. SnCl4 formation in the precursor mixture was confirmed by visible spectrophotometric measurements. The substitution of Ti02 by Sn02 results in a significant increase in electrochemically active surface area, as supported by scanning electron microscopy, anodic voltammetric charge, q, and the double-layer capacity, Cdl, as a function of composition. Roughness factors between 3600 and 5100 were obtained. A linear Cdl vs. q, graph with an angular coefficient close to one was obtained.) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 128.255.6.125 Downloaded on 2015-05-23 to IP