Electrochemical properties of the IrO2-Ta2O5 coated anodes with Al/Ti and Cu/Ti layered composites substrates

Highlights: • Al/Ti and Cu/Ti layered composites are prepared by plasma spraying hot-pressing-bonding technique. • Al/Ti and Cu/Ti layered composites are the substrate of the IrO₂-Ta₂O₅ coated anodes. • The structure of layered composite improves the conductivity and electrochemical properties of the anode. • The distribution of electric potential on the surface of layered composite anodes are more uniform. In this paper, the Al/Ti and Cu/Ti layered composite was prepared by the hot-pressing-bonding technique as the basic material of the anodes, and the IrO₂-Ta₂O₅ coatings were thermally deposited on the different kinds of the matrix. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectrometer (EDS) were used to study the Al/Ti and Cu/Ti layered composite and IrO₂-Ta₂O₅ coatings. The electrochemical performance of Ti/IrO₂-Ta₂O₅, Al/Ti/IrO₂-Ta₂O₅ and Cu/Ti/IrO₂-Ta₂O₅ composite anodes was studied by linear sweep voltammetry (LSV), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results indicate that the electrochemical performance of Al/Ti/IrO₂-Ta₂O₅ and Cu/Ti/IrO₂-Ta₂O₅ anodes, compared to the Ti/IrO₂-Ta₂O₅ anode, was effectively improved. Layered composite structure can significantly reduce the resistance and improve the conductivity of the substrate, and the reduction of resistance in electron transfer from electrode to reactants was observed. Because of the resistivity of Cu was the smallest, the resistivity of Cu/Ti layered composite was the lowest (5.1 × 10⁻⁸ Ω m), the anodic polarization performance and the electro-catalytic activity of Cu/Ti/IrO₂-Ta₂O₅ anode were the best. The surface electric potential of the Al/Ti/IrO₂-Ta₂O₅ and Cu/Ti/IrO₂-Ta₂O₅ anodes were lower than that of Ti/IrO₂-Ta₂O₅ anode, and the distribution of electric potential on the surface of layered composite anodes was more uniform than that of Ti/IrO₂-Ta₂O₅ anodes.