The Utilization of Iridium Nanoparticles Impregnated on Metal Oxides (Ceria, Titania, and Zirconia) with a Simple and Ecologically Safe Synthesis Approach in Oxygen Evolution Reactions

Oxygen evolution reactions (OERs) have sluggish kinetics, which limits the hydrogen generation from the electrolysis of water. In this regard, various metal oxides based electrocatalysts that contain precious metals such as Pt, Ir, Rh, and Ru have been developed for OERs in the literature In this work, Ir nanoparticles were impregnated on the surface of metal oxides (MO 2 ; M = Ti, Zr, and Ce) using a simple and ecologically acceptable approach (reduction and impregnation in water). The electrocatalytic performance of the prepared catalysts (Ir/MO 2 ) was tested for OER in an alkaline medium. The results show that the onset potentials of Ir/MO 2 catalysts have slight variations (1.552 V vs RHE for Ir@CeO 2 , 1.554 V vs RHE for Ir@ZrO 2 , and 1.598 V vs RHE for Ir@TiO 2 ) in this reaction. The overpotential and the Tafel slope values of these catalysts were also compared and it was found that the Ir@CeO 2 catalyst provided the lowest overpotential value ( η 10 = 0.379 V vs RHE) and the lowest Tafel slope value (b = 93.4 mV.dec −1 ). Herein, the activity and stability of Ir@CeO 2 towards OER in alkaline media were investigated in detail with electrochemical impedance spectroscopy, chronoamperometry, and linear sweep voltammograms taken at different temperatures.