Microstructure and electrochemical properties of IrO2+RhOx+ZrO2 coated titanium anodes

The electrodes of Ti/IrO2+RhOx + ZrO2 were prepared with varying proportions of RhOx using thermal decomposition treatment at 550 degrees C. The microstructure of these coatings was investigated by SEM and XRD methods. The electrochemical behavior of coatings was assessed through accelerated life test (ALT), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The results showed that increasing the RhOx content led to superior service lifetime and lower electrical conductivity of the coatings. Also, the results of cyclic voltammetry tests confirmed that the anodic voltammetric charge was enhanced by increasing the concentration of RhOx in coatings. The EIS examination of the coatings indicated that the charge transfer resistance at the external active surface of the coatings was increased by adding the RhOx content. Furthermore, it was found that the formation of TiO2 passive layer at the interface of the substrate/oxides layer was the main destruction mechanism of the coated anodes. Among the tested anodes, the anode with 10%IrO2-60%RhOx-30%ZrO2 coating exhibited larger electrochemically active surface area, higher stability and inferior electrocatalytic activity for oxygen evolution. (C) 2019 Elsevier Ltd. All rights reserved.