Electrochemical Behaviour of Industrial IrO₂-Ta₂O₅Anodes for Copper Electrowinning

Abstract

In this work, industrial IrO 2 -Ta 2 O 5 anodes calcined at different temperatures were investigated. The results show that the calcination temperature has significant influence on the surface microstructure including the crystallinity and the preferred orientation of IrO 2 crystallite of the formed IrO 2 -Ta 2 O 5 binary oxide. The IrO 2 phase is partially amorphous at low calcination temperature in the present study. The (101) IrO 2 planes dominate at low or moderate calcination temperatures, whereas the (110) IrO 2 orientation was preferred at the highest calcination temperature.Surface morphology of the anodes was revealed as mud-cracks surrounded by a flat area with plenty of scattered nano-IrO 2 crystallites. The size of the nano-IrO 2 crystallites is calcination temperature dependent, which in turn determines the electrochemical active surface area (ECSA). In this IrO 2 -Ta 2 O 5 binary oxides coating, (101) IrO 2 was found to have higher catalytic activity than (110) IrO 2 with respect to the oxygen evolution reaction (OER).The moderate temperature is suggested as the best calcination temperature for this certain anode regarding the ECSA, electrocatalytic activity for OER and stability potential.