Iridium-oxide-coated titanium electrodes used for oxygen and chlorine evolution are usually prepared using a complicated thermal decomposition process. To simplify preparation iridium was plated on to a titanium substrate and the plated iridium oxidized by electrolysis or heating. The electrode's electrochemical behavior after electrolysis or heating to oxidize iridium was studied in H2SO4 and NaCl solutions. When the electrode was electrolyzed in NaCl solution for 500 cycles using a rectangular wave of ±75mA/cm2, the overpotential for oxygen or chlorine evolution was marked reduced, due perhaps to two reasons for this. One involves the formation of iridium hydroxide by electrolysis, which indicates catalytic activity. The other involves cracks formed on the electrode surface by electrolysis, which increases the electrode surface and decreases the real current density and overpotential.
