A comparative study of commercial and laboratory-made Ti/Ru0.3Ti0.7O2 DSA® electrodes: “In situ” and “ex situ” surface characterisation and organic oxidation activity

This paper presents the study of two dimensionally stable anodes (DSA®) of nominal composition Ti/Ru0.3Ti0.7O2, one obtained commercially and the other prepared in the laboratory. The materials were studied by ex situ (scanning electron microscopy (SEM)) and by in situ techniques (cyclic voltammetry, determination of the morphology factor (φmorph) and electrochemical impedance spectroscopy (EIS)). The results obtained indicate that both electrodes present similar morphology and voltammetric profiles, with the main difference between the two materials studied being the internal electrode area, with the commercial electrode being demonstrated to possess the greater. The EIS study demonstrates that the differences in the equivalent circuit fitting parameters can be related to the different surface characteristics of the electrodes. However, the abnormal dependence of the solution ohmic resistance on the potential demonstrates that the model should be refined to be adequately applied to commercial electrodes. A study of the activity for organic oxidation was also performed, with the aim of verifying the effect of chain length on the rate of oxidation of different aldehydes (formaldehyde, acetaldehyde, propionaldehyde and n-butyraldehyde). It can be observed that the rate of carboxylic formation can be related to the working electrode potential during electrolysis, with higher potentials (commercial electrode) seeming to favour the more rapid formation of the carboxylic acid.