Electrospun Ti–Zr Oxide Heterostructures Enable Strongly Anchored Ultralow-Ir Anodes for Durable Acidic Oxygen Evolution

Developing ultralow-Ir anode catalysts is desperately needed for proton-exchange-membrane water electrolysis, which requires high activity and adequate stability for the challenging acidic oxygen-evolution reaction. Here, we report a Ti–Zr composite electrospun oxide (ESO) nanorod support that enables high-performance ultralow-Ir anodes. The Zr-containing Ti oxide heterostructures are effective in stabilizing anatase-rich TiO₂, tuning the local oxygen-coordination environment, and strengthening the interfacial anchoring of IrO_x under acidic anodic conditions. The electrospun porous nanorod network further creates an open, mechanically coherent catalyst layer, thereby improving Ir utilization, ionomer penetration, and mass transport in the ultralow-Ir anode. At a loading of 0.2 mg_Ir cm^–2, the optimized Ir/TiZr₂₀-ESO anode delivers a mass activity of 0.99 A mg_Ir^–1 at 1.45 V, more than 40 times higher than a commercial TiO₂-supported IrO₂ catalyst. The anode presents compelling performance and durability, achieving 3.0 and 4.0 A cm^–2 at 1.75 and 1.83 V, respectively, and sustaining 2000 h of operation at 2.0 A cm^–2. Accelerated stress tests up to 525 h over 31,500 cycles also confirm promising long-term durability under dynamic conditions, demonstrating an insignificant decay of 0.4 μV per cycle. Theoretical calculations elucidate that the Ti–Zr oxide heterostructure can suppress Ti demetalation and strengthen IrO₂ interfacial binding, rationalizing the improved long-term durability of the ESO-supported ultralow-Ir anode.