Nb-DOPED TiO2 SUPPORTS ENABLE HIGH OER ACTIVITY AT REDUCED IRIDIUM LOADING

The scarcity of iridium (Ir) remains a key barrier to large-scale deployment of proton exchange membrane water electrolyzers (PEMWEs). To address this challenge, we demonstrate that Nb-doped TiO2 (NbTiO) serves as an optimal support to enhance both the electrochemical activity and durability of Ir catalytic sites toward the oxygen evolution reaction (OER). By balancing crystallinity and surface area, Nb-doping improves electronic conductivity without compromising the uniform dispersion of Ir nanoparticles. The optimized Ir/NbTiO catalyst (50 wt.% Ir) exhibits fine particle dispersion (~2.5 nm), high electrochemically active surface area, and tailored metal-support interactions. Consequently, the catalyst delivers an outstanding balance between high specific activity (6.2 mA C⁻¹) and exceptional durability, retaining over 95% of its initial performance following extended operation. Fundamentally, incorporating Nb into the TiO2 crystal lattice promotes the intrinsic activity of Ir while ensuring efficient charge transport and sustained stability of the active sites. These findings reaffirm NbTiO as a robust and promising support platform, offering a viable pathway to minimize iridium loading in next-generation PEMWE anodes.