Optimizing Acidic Oxygen Evolution Reaction via Modulation Doping in Van der Waals Layered Iridium Oxide

Anodic oxygen evolution reaction (OER) exhibits a sluggish four-electron transfer process, necessitating catalysts with exceptional catalytic activity to enhance its kinetic rate. Van der Waals layered oxides are ideal materials for catalyst design, yet its stability for acidic OER remains large obstacle. Doping provides a crucial way to improve the activity and stability simultaneously. However, doping in Van der Waals layered oxides remains a great challenge since it easily leads to lattice distortion or even the crystal structure damage. In this work, we successfully doping acid-resistant niobium (Nb) into Van der Waals layered edge-shared 1T phase iridium oxide (1 T-IrO₂) via alkali-assisted thermal method. 1 T-IrO₂ with a 5 % Nb doping (Nb_0.05Ir_0.95O₂) only required an overpotential of 191 mV to achieve a current density of 10 mA cm^-2 in 0.5 M H₂SO₄, 56 mV lower than that of 1T-IrO₂. When applied in proton exchange membrane water electrolyzer, Nb_0.05Ir_0.95O₂ show stable operation at a high current density of 1.2 A cm^-2 for over 50 days. Density functional theory calculation reveals that doping Nb changes the potential-determining step from the *OOH deprotonation process in 1 T-IrO₂ to the *O-OH coupling process in Nb_0.05Ir_0.95O₂.