Structure–Activity/Stability Correlations from the Electrochemical Dynamic Responses of Titanium Anode Coatings Formed of Ordered TiO2@RuO2 Microspheres

Spherical TiO2/RuO2 particles were synthesized by ultrasonic spray pyrolysis (USP) at 200 and 800◦C. The activity for the oxygen and chlorine evolution reactions (OER and CER, respectively) and the dynamic responses from electrochemical impedance spectroscopy (EIS) of the USP powders, as well as of the corresponding coatings on Ti, were analyzed and are discussed. The loss of coating activity is discussed with respect to the differences in the EIS and cyclic voltammetry responses of the coatings in their active and inactive states. The 800°C-USP sample was found to be more active than the 200°C-USP sample for both the CER and the OER, whereas the stability of the former was considerably lower. The correlation between the structure, composition and morphology of the powder and the coating with the registered electrochemical properties is discussed. The EIS analysis of the coating resistance distributions induced by the thermal treatment of the powder indicated a complex combination of the pore resistance and the pseudocapacitive charge transfer resistance. An additional coating resistance, due to loose grain boundaries, was introduced into the coatings in their active and inactive state. The EIS analysis indicated the changes in TiO2-enriched core/RuO2-enriched shell structure, caused by the USP temperature. © The Author(s) 2018. Published by ECS