Improvement in the chlorine evolution activity of an SnOx@IrO2–Ta2O5 electrode and its application in the electrolysis of an extremely dilute chlorine-containing solution.

It is imperative to solve the problem of the electrolytic efficiency of chlorine evolution in extremely dilute chlorine-containing solutions for electrochemical advanced oxidation processes, electrochemical antifouling and chlorine-containing disinfectant preparation. In this paper, an IrO2–Ta2O5 electrode is modified using SnOx, and the activity and selectivity of the chlorine evolution reaction (CER) are successfully improved. The modification of SnOx changes the electronic structure of IrO2–Ta2O5, thus affecting the electrochemical reaction process and mechanism. Compared with the CER activity of the IrO2–Ta2O5 electrode, the CER activity of the SnOx@IrO2–Ta2O5 electrode is increased, whereas the OER activity is decreased. At a current density of 50 mA cm−2, the potential difference between the CER and OER of the SnOx@IrO2–Ta2O5-3 electrode is 254 mV, which is 89 mV higher than that of the IrO2–Ta2O5 electrode. This proves that the selectivity of the CER at the SnOx@IrO2–Ta2O5 electrode has been improved. Due to the low concentration of chloride ions, the current efficiency of the IrO2–Ta2O5 electrode is only 10.7%. The current efficiency of the SnOx@IrO2–Ta2O5-1(2,3) electrode increases to 23.6%, 36.7% and 49.6%, respectively. For the IrO2–Ta2O5 electrode, its rate-determining step (RDS) is the second electron transfer. However, for the SnOx@IrO2–Ta2O5-3 electrode, its RDS is electrochemical desorption. It can be inferred that the modification of SnOx can accelerate the electrochemical desorption of adsorbed Cl. In addition, the application of the SnOx@IrO2–Ta2O5 electrode in the preparation of AEW is investigated. The HClO content in AEW2 (prepared using the SnOx@IrO2–Ta2O5-3 electrode) is 1.85 mmol L−1, which is 4.6 times of that in AEW1 (prepared using the IrO2–Ta2O5 electrode). [ABSTRACT FROM AUTHOR]