Electrochemical properties of IrO2-Ti2O5-Co3O4 coated Ti anode in acid media

• Published in: Surface & coatings technology 2019-09, Vol.374, p.815-821
• Main Authors: Alanazi, Nayef M., Al-Abdulhadi, Abdullatif I., Al-Zharani, Talal Y., Al-Khaldi, Turki A., Alghamdi, Rasha A., Al-Shaikh Ali, Anaam H., Shen, Shouwen
• Format: Article
• Language: English
• Subjects: Anodes; Anodic coatings; Cathodic protection; Coatings; Cobalt oxide; Cobalt oxides; Cyclic voltammetry; Electrocatalyst; Electrochemical analysis; Electrochemical impedance spectroscopy; Electrode polarization; Electrolysis; Electron microscopes; Iridium; Iridium oxide; Morphology; Oxygen evolution; Service life; Substrates; Sulfuric acid; Tantalum oxides; Thermal decomposition; Thermal decomposition fabrication; Titanium; X-ray fluorescence
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2019.06.059

Iridium oxide-tantalum pentoxide (IrO2–Ta2O5) coated anodes were prepared by thermal decomposition on a tubular titanium substrate with and without cobalt salts containing a precursor. The surface morphology and microstructure of the deposited coatings were investigated by use of an environmental scanning electron microscope (ESEM), X-ray fluorescence (XRF) spectrometry and scanning transmission electron microscope (STEM). The electrochemical properties of the deposited thin coatings were examined by cyclic voltammetry, potentiodynamic polarization scan and electrochemical impedance spectroscopy (EIS) techniques. The service life cycle of the applied coatings was evaluated under electrolysis at a constant current density of 1 A cm−2 in 1 M sulfuric acid (H2SO4) solution. The role of cobalt oxide (Co3O4) in the electrocatalytic activity and stability of IrO2–Ta2O5 coating are discussed. A small amount of Co3O4 resulted in improving the life cycle of the IrO2-Ta2O5 anode in the 1 M H2SO4 solution due to dense nature coating. Meanwhile, the Co3O4 had no significant contribution to the electrochemical measurements. •A small addition of Co3O4 into the IrO2-Ta2O5 coating makes the coating structure more compact and coherent.•The addition of Co3O4 can cause significant performance in the accelerated life test to be achieved.•There is no significant influence of Co3O4 addition into the IrO2-Ta2O5 coating on the anodic behavior of oxygen evaluation.