Morphology, Microstructure, and Electrocatalytic Properties of RuO2 ‐ SnO2 Thin Films

Abstract

The electrochemical devices based on conductive stabilized by ceramic oxides are the most employed in chlorine‐alkali cells. Their efficiency is influenced by many variables, among which the chemical nature of the stabilizer oxide plays a considerable role. In this paper, morphology, microstructure, and electrocatalytic properties of supported thin films, prepared in a wide compositional range, were investigated by X‐ray diffraction (XRD), scanning tunneling microscopy (STM), and cyclic voltammetry (CV). X‐ray analysis indicates an immiscibility zone for the two oxides approximately in the range 20–70 atom % of Sn nominal amounts. In both solubility regions, a tetragonal phase (rutile‐type) is formed. Peak profile analysis indicates a nonequiaxial crystal growth and shows that in solid solutions where is the major component larger crystallites (about 100–160 Å) are formed than in those where is the major component (about 30 Å). STM characterization reveals a rough surface with a complex microstructure: very large agglomerates, which seems to be made up of a large number of smaller units with sizes of the same order of magnitude found by XRD. Only in the sample with 70 atom % of Sn (nominal amounts) there exists regions where the small units are clearly visible as distinct particles. The CV analysis shows that the highest electrocatalytic activity is exhibited by the latter sample, which has the highest possible content of before it forms a solid solution in and where particles tend not to form aggregates. © 1999 The Electrochemical Society. All rights reserved.