The influence of the synthesis method of Ti/RuO2 electrodes on their stability and catalytic activity for electrochemical oxidation of the pesticide carbaryl

In this study, we developed dimensionally stable anodes of titanium covered with ruthenium oxides (Ti/RuO2) using sol-gel, Pechini and ionic liquid (IL) methodologies. The electrochemical efficiency of these electrodes was then evaluated regarding electrochemical degradation of the pesticide carbaryl. The UV-visible spectroscopy measurements showed that the electrodes obtained by the IL and Pechini methods were more effective at pesticide degradation compared with the sol-gel electrode, especially at high current density values. Carbaryl degradation after 2 h of electrolysis at 30 mA cm−2 was 96.4% and 95.5% for the electrodes obtained by the IL and Pechini methods, respectively, while the degradation was 65.0% for the electrodes obtained by the sol-gel method. Additionally, the electrodes prepared by the IL and Pechini methods showed greater physical and electrochemical stability when compared to electrodes obtained by the sol-gel method. Electrodes prepared by the IL method with a few covering layers (three) achieved an elevated and constant area in a more efficient way than electrodes prepared by the Pechini and sol-gel methods. This fact can be attributed to the higher viscosity of the ionic liquid-based precursor solution, which transfers a higher amount of Ru in one single layer, compared to the other methods studied, thus reducing the time for synthesis, the number of calcination steps and the production costs of electrodes.