Evaluation of the electrochemical activi

Most of the hydrometallurgical processes use sulphuric acid solutions, where the main anodic reaction is oxygen evolution by decomposition of water. Traditional anode materials, primarily lead alloys, exhibit high overpotential towards oxygen evolution. This research investigates the activities of binary RuO2–TiO2 anodes using various electrochemical techniques, including cyclic voltammetry and potentiostatic tests. The measurements focused on the redox reaction between Ru(III) and Ru(IV) and the oxygen evolution reaction evaluated through galvanostatic electrochemical impedance spectroscopy. The study found that the intrinsic electrocatalytic properties and electrochemically active surface area could be distinguished, revealing that increasing the active oxide concentration above 30 mol% does not lead to a significant boost in activity towards oxygen evolution. In cases with low amounts of active oxide, most active sites are concealed within pores and cracks, ultimately causing anode failure due to bubble formation. This work contributes to the understanding of anode material performance in electrochemical applications, highlighting operational limits in relation to active oxide concentrations.