Spontaneous Deposition of Iridium onto Nickel Substrates for the Oxygen Evolution Reaction
Spontaneous deposition of Ir onto Ni substrates was investigated as a method to produce electrocatalytic layers for the oxygen evolution reaction in 30% KOH solution. UV/Vis spectroscopy, cyclic voltammetry and other electrochemical methods are used to investigate the deposition process and the activity of the electrocatalytic coating towards the oxygen evolution reac- tion. From three solutions (IrCl3+HCl, H2IrCl6+HCl, and H2IrCl6), H2IrCl6 is shown to give the most active and stable coating, with deposition times of 45 minutes at 60 ◦C enough to increase the activity of the Ni substrate for the oxygen evolution reaction. It is proposed that Ir deposition can occur via the reduction of the Ir precursor coupled to Ni oxidation, as well as the hydrolysis and localised precipitation of the Ir precursor due to the increase in surface pH during Ni dissolution.