Nanoplatinum-Enhanced Ultralow-Iridium-Loading Porous Electrode for Efficient Water Oxidation

Iridium oxide (IrO₂) electrodes suffer from their high costs caused by the high iridium loading, which severely hinder their large-scale application in the oxygen evolution reaction (OER). In this work, platinum nanoparticles (Pt NPs) are employed as a nanofiller layer on matrix porous titanium (MPT) to fabricate a porous IrO₂ electrode (IrO₂@Pt/MPT). Despite its Ir loading being as low as 0.0126 mg_Ir/cm², it exhibits good OER performance in both neutral and acidic solutions, achieving a potential of 1.9 V at 50 mA cm² (0.01 M Na₂SO₄) and a mass activity of up to 25577.8 A/g_Ir at 1.53 V (0.5 M H₂SO₄). Density functional theory calculations and in situ Raman spectra reveal that its superior OER originates from the synergistic effect of IrO₂ and Pt. It suggests that the heterogeneous interface capacitance induces charge reconstruction on the IrO₂, which enhances the surface Ir-O covalency and ultimately reduces the rate-determining step energy barrier on the (101) plane. The electrode stability is evaluated in CO₂ electroreduction, demonstrating long-term stability and good reusability in three 100 h stability evaluations. IrO₂@Pt/MPT shows a negligible voltage rise with an iridium loss of 3.97% in anodic corrosion and 4.76% in exfoliation. This work provides a potential strategy for designing low-iridium porous OER electrodes.