Hypochlorite Oxidation on RuO2-Based Electrodes: a Combined Electrochemical and In Situ Mass Spectroscopic Study

The hypochlorite oxidation on RuO2 doped with Co, Mg, Ni and Zn was studied by means of voltammetry combined with mass spectroscopy. The hypochlorite oxidation takes place in two distinct steps separated with at least 200 mV. While the first step can be assigned to the direct hypochlorite oxidation, the second one seems to be connected with the oxidation of strongly adsorbed in situ formed hypochlorite. In the oxidation process of hypochlorite, oxygen is the main product but also hydrogen peroxide can be detected. The number of electrons used to produce one molecule of oxygen (z) is less than expected from an electrochemical point of view. This fact, together with an accumulation of chloride ions in solution, indicates that the reaction mechanism of the hypochlorite oxidation involves the formation of radicals that can be regenerated by chemical redox reactions.