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