Ultralow interface resistance in porous transport electrode for efficient polymer electrolyte membrane water electrolysis at low Ir loading

Achieving high-efficiency polymer electrolyte water electrolysis (PEMWE) with minimal use of precious metals remains a critical challenge for clean hydrogen production. A major bottleneck is the interface resistance within the membrane-electrode-diffusion layer, especially under low catalyst loadings. Here, a simple yet powerful catalyst-integrated diffusion layer fabrication strategy is presented that enables ultralow interface resistance even at reduced Ir loadings. By directly synthesizing a TiO 2 -supported IrO x catalyst (TiO 2 -IrO x ) onto the Ti felt through a single-step calcination, a porous transport electrode (PTE) is constructed and it serves as a high-performance anode. At an optimized Ir loading of only ~0.12 mg Ir cm −2 , the TiO 2 -IrO x PTE exhibits exceptional current density of 2.54 A cm −2 at 1.9 V, outperforming state-of-the-art benchmark electrodes. Moreover, even after long-term durability test with ultra-low loadings (<0.1 mg Ir cm −2 ), the ultralow interface resistance of the TiO 2 -IrO x PTE is maintained. As a result, the TiO 2 -IrO x PTE achieves a significantly high mass activity of 20 A mg Ir −1 at 1.9 V, far surpassing conventional Ir-based electrodes. This work provides a compelling pathway toward reducing dependence on scarce platinum-group metals without compromising performance of PEMWE system. • Spray-based fabrication of porous transport electrode for PEM water electrolysis. • Binder-free and Pt-free anode architecture for scalable and cost-effective design. • Ultralow interface resistance at low Ir loading (<0.1 mg cm −2 ). • High mass activity at 1.9 V, outperforming state-of-the-art Ir-based anodes.