Oxide electrocatalytic coatings obtained by the sol-gel procedure: Preparation and characterization

The influence of different parameters (forced hydrolysis duration in the preparation of sols, alcohol addition in the sol mixture for application, as well as sol/alcohol mixture ageing time) on the morphology and electrochemical properties of RuO2-TiO2 coatings obtained by the sol-gel procedure is presented. The oxide sols were sharacterized by spectroscopic and microscopic methods (X-ray diffraction, TEM, etc). The morphology of the obtained coatings was examined by scanning tunneling microscopy, while the electrochemical properties were investigated by cyclic voltammetry polarization measurements, electrochemical impedance spectroscopy and the accelerated stability test. The greatest real surface area was obtained for coatings with the smallest RuO2 particles and largest TiO2 particles. Alcohol addition caused enlargement of the oxide grains and, consequently, a decrease in the real surface area. The same effects of oxide grain size were registered on electrochemically active surface area. The electrocatalytic activity of the obtained anodes for the chlorine evolution reaction increased with growth of the TiO2 particles, but depended on the RuO2 particle size to a small degree. The corrosion stability of the anode coatings consisting of the smallest RuO2 particles and largest TiO2 particles whis the greatest in the electrolysis of a sodium-chloride solution