Efficient and Stable Evolution of Oxygen Using Pulse-Electrodeposited Ir/Ni Oxide Catalyst in Fe-Spiked KOH Electrolyte

Metal oxides have been extensively explored as catalysts for the electrochemical oxygen evolution reaction (OER). Here, we present an excellent OER catalytic system consisting of pulse-electrodeposited Ir/Ni oxides in Fe³⁺-spiked 1 M KOH. In pure 1 M KOH electrolyte, the optimized catalyst, which had an Ir:Ni atom ratio of 1:1.49, could catalyze 10 mA/cm² of O₂ production at a small overpotential of 264 mV. Remarkably, we found that its OER performance could be significantly improved by adding 0.3 mM Fe³⁺ into the electrolyte. At an of just 343 ± 3 mV, a huge current of 500 mA/cm² was achieved. Furthermore, this catalytic system exhibited a small Tafel slope of 31 mV/dec and a large iridium mass-normalized current of 1260 mA/mg_Ir at = 280 mV. We also discovered that the durability of the Ir/Ni oxide catalyst during OER (at 10 mA/cm² with < 280 mV) could be maintained for more than 4.5 days by simply spiking Fe³⁺, Ir³⁺, and Ni²⁺ into the KOH electrolyte. The figures-of-merit in this work, in terms of both activity and stability, compare favorably against values from several state-of-the-art catalysts. Hypotheses for the outstanding performance of the Ir/Ni catalyst are proposed and discussed.