Exploration of the Thermally Prepared Iridium Oxide (IrO2) and Tantalum Pentoxide (Ta2O5) Coated Titanium Anode in the Oxygen Evolution Reactions (OER)

摘要

A coat consisting of IrO2-Ta2O5 as a catalytically active layer on a titanium substrate was prepared by the thermal decomposition method followed by the anodic electrolysis process in an aqueous solution of H2SO4 0.5 mol.dm-3 at 4 A.Cm-2 current density. The morphology and the composition of the coating were investigated both by the field emission scanning electron microscope (FE-SEM) coupled with the energy dispersive X-ray spectrometer (EDS), X-ray diffraction (XRD), and by X-ray photoelectron spectroscopy (XPS). The XRD and the XPS experimental results revealed that some of the texture coefficients of IrO2-rutile crystal preferentially grown and the crystal lattice changes with aging time in air furnace at 100 °C. It was observed that at 4 A.Cm-2, this coated material behaves as a good catalytically active layer for oxygen evolution reactions (OER). The OER process leads to the corrosion of the surface banks layer by layer, and consequently the cracks appeared and expanded, resulting in fragmentation and further peeling. The EDS results revealed that during the electrolysis of the coated electrode there was a selective consumption of the iridium oxide. The presence of titanium metal was detected in the outermost coating. This might be originated from the titanium foil dissolved and diffused through the coated layer defects during the electrolysis process.