A comparative study on the role of nanotubes and micropores of titanium oxide interlayer on the electrochemical properties of the mixed metal oxide coating

Abstract

In order to extend the service life of a typical mixed metal oxide (MMO) anode, titanium oxide nanotubes (TiO2-NTs) and micropores (TiO2-MPs) were produced on titanium substrate in this study. This was accomplished by anodizing titanium substrate in hydrofluoric acid and sulfuric acid solutions, respectively, to grow these interlayers. Next, the composition's mixed metal oxide (MMO) coating—which contained tantalum, ruthenium, and iridium oxide—was created by thermal decomposition of appropriate precursors at 480 °C. The corrosion pathways, electrochemical characteristics, and deactivation mechanism of anodes were assessed at various ALT test time intervals using the Accelerated Lifetime Test (ALT) and Electrochemical Impedance Spectroscopy (EIS). Additionally, field emission scanning electron microscopy (FE-SEM) was used to characterize the coatings and interlayers. In contrast to the base sample and the Ti/TiO2-MPs/MMO electrodes, the analysis of surface morphology revealed that the surface of the Ti/TiO2-NTs/MMO electrode following anode deactivation did not have a coating with the same structure as the base sample. Additional findings corroborated that the primary mechanism responsible for the deactivation of the Ti/TiO2-NTs/MMO electrode was the uniform dissolution of the coating. Conversely, it was found that the TiO2-MPs interlayer caused the anode's life to drop by 61% in comparison to the base sample, but the TiO2-NTs interlayer lengthened it. Thus, it can be concluded that the TiO2-NTs interlayer thickness the surface coating, preventing oxygen from reaching the substrate and preventing cracking as a result, potentially delaying passivation.