THE ROLE OF SOL-GEL PROCEDURE CONDITIONS IN ELECTROCHEMICAL BEHAVIOR AND CORROSION STABILITY OF Ti/[RuO₂-TiO₂] ANODES

ABSTRACT

Using a sol-gel procedure, RuO₂-TiO₂ active coatings were formed on a titanium support. The conditions of preparation of the RuO₂ and TiO₂ sols were investigated and the sols were characterized by transmission electron microscopy (TEM) and X-ray diffraction technique. Prepared anodes were investigated from the standpoint of morphology (scanning tunneling and electron microscopy) and electrochemical behavior (cyclic voltammetry, polarization measurements, and electrochemical impedance spectroscopy). The service life of the RuO₂-TiO₂ active coatings was examined by an accelerated corrosion stability test in 0.5 ;mol dm⁻³ NaCl solution. In order to resolve the role of TiO₂ in the deactivation mechanism of the active coating, additional TiO₂ layers were introduced in the support/coating interface or on the surface of the coating. The behavior of these anodes with the TiO₂-enriched coating layer was compared with the behavior of anodes with regular RuO₂-TiO₂ coatings. The results show that the loss of coating electrocatalytic activity is caused by dissolution of active Ru species and TiO₂ enrichment in the coating. It is also observed that the sol-gel preparation procedure favors the formation of the TiO₂ layer at the surface of the RuO₂-TiO₂ coating.

Key Words:

• Forced hydrolysis
• Oxide sols
• Aging time
• TEM
• XRD
• Sol-gel procedure
• RuO₂-TiO₂ coating
• Corrosion stability
• SEM
• STM
• Cyclic voltammetry
• Polarization measurements
• Pseudocapacitance
• Electrochemical impedance spectroscopy
• Pore resistance

ACKNOWLEDGMENT

The research is financially supported by the Ministry of Science, Technologies and Development, Republic of Serbia, Project No. 1230.

Notes

*RT = [RuO₂ − TiO₂]; T = TiO₂.