A modular functionalized anode for efficient electrochemical oxidation of wastewater: Inseparable synergy between OER anode and its magnetic auxiliary electrodes

Oxygen evolution reaction (OER) anodes, (e.g., IrO2) are well-known inefficient catalysts for electrochemical oxidation (EO) of refractory organics in wastewater due to the high energy consumption via OER. However, in this study this kind of anode participated in a very effective EO process via a specific modular anode architecture. Traces of magnetic Fe3O4/Sb-SnO2 particles as auxiliary electrodes (AEs) were attracted on the surface of the two-dimensional (2D) Ti/IrO2-Ta2O5 by a NdFeB magnet, and thereby constituted a new magnetically assembled electrode (MAE). MAE could be renewed by recycling its AEs. The electrochemical properties as well as the EO performances of the MAE could be regulated by adjusting the loading amount of AEs. Results showed that even a small amount of AEs could increase surface roughness and offer massive effective active sites. When removing color of azo dye Acid Red G, the optimal MAE exhibited similar to 1100 % and similar to 500 % higher efficiencies than 2D Ti/IrO2-Ta2O5 and 2D Ti/Sb-SnO2, respectively. The superiority of the MAE was also applicable in degrading phenol. The synergy between Ti/IrO2-Ta2O5 and magnetic Sb-SnO2 particles was therefore discussed.