High-Performance Low-Iridium Catalyst for Water Oxidation: Breaking Long-Ranged Order of IrO₂ by Neodymium Doping

Exploring efficacious low-Ir electrocatalysts for oxygen evolution reaction (OER) is crucial for large-scale application of proton exchange membrane water electrolysis (PEMWE). Herein, an efficient non-precious lanthanide-metal-doped IrO₂ electrocatalyst is presented for OER catalysis by doping large-ionic-radius Nd into IrO₂ crystal. The doped Nd breaks the long-ranged order structure by triggering the strain effect and thus inducing an atomic rearrangement of Nd─IrO₂ involving the forming of Nd─O─Ir bonds along with an increased amount of oxygen vacancies (O_v), giving rise of a long-ranged disorder but a short-ranged order structure. The formed Nd─O─Ir bonds tailor the electronic structure of Ir, leading to a lowered d-band center that weakens intermediates absorption on Ir sites. Moreover, doping Nd triggers Nd─IrO₂ to catalyze OER mainly through lattice oxygen mechanism (LOM) by activating lattice oxygen owing to abundant O_v. The optimal catalyst only requires a relatively low overpotential of 263 mV@10 mA cm^-2 with a high mass activity of 216.98 A g_Ir ^-1 (at 1.53 V) (eightfold of commercial IrO₂), and also shows a superior durability at 50 mA cm^-2 (20 h) than commercial IrO₂ (3 h) due to the oxidation-suppressing effect induced by Nd doping. This work offers insights into designing high-performance low-Ir electrocatalysts for PEMWE application.