Morphology of Ultrafine RuO2-1rO2 Binary Oxide Particles Prepared by a Sol-Gel Process

Ultrafine particles of RuO2-1rO2 binary oxides with various compositions of Ru and Ir have been prepared by a sol-gel process consisting of hydrolysis and condensation of metal ethoxide thanol solutions. The (Ru, Ir)O2 rutile-type solid solution of binary oxides was formed. High-resolution scanning electron microscopy micrographs of t eRu-lr binary oxides showed the spherical-like crystallites for Ru-rich oxides and needle-like ones for I-rich oxides. The particle size was the smallest for the binary oxide with comparable Ru-lr composition. RuO2-1rO2 binary oxide-coated titanium electrodes are important anodes in the chlorine evolution for the sodium chloride lec-trolysis. 1 A variety of microanalyses have revealed the surface morphology and composition of RuO2 and/or IrO2-based oxide electrodes. 2-11 Small islands were formed on the flat surface for Ru-or Jr-rich oxide. 1 ~ These islands mainly consisted of ruthenium and iridium oxides. Recently, using high resolution scanning electron microscopy (SEM), the microstructure of the islands was proved to consist of aggregates of small crystallites. 11Since the crystallites were too small for measuring their composition by energy-disper