Tailoring the Electronic Structure of Ir Alloy Electrocatalysts through Lanthanide (La, Ce, Pr, and Nd) for Acidic Oxygen Evolution Enhancement

The oxygen evolution reaction (OER) is critical for renewable energy conversion and storage devices. However, the rational design of electrocatalysts with suitably high efficiency and stability in strongly acidic electrolytes remains a major challenge. Herein, a solid-phase synthesis strategy is developed for the preparation of Ir-Ln (Ln = La, Ce, Pr, Nd) alloy nanoparticles with uniform particle size on carbon supports as superior acidic OER catalysts. Tailoring by the rare earth (RE) elements, Ir₂Pr achieves a maximum mass activity of 2.10 A mg⁻¹_Ir at 300 mV overpotential and stability over 200 h at 10 mA cm⁻² in 0.5 m H₂SO₄, which is 9.5 and 20 times higher to pure Ir nanoparticles. Furthermore, Ir₂Pr alloy nanoparticles exhibit excellent durability in strongly acidic electrolytes. Theoretical calculations have confirmed that the OER performances are strongly related to the RE elements in the alloy, where the d-band centers show a consistent trend with the overpotential. Moreover, the highest electroactivity of Ir₂Pr is attributed to the improved electron transfer by 4f orbitals and the suitable binding strength of intermediates. Herein, a fundamental understanding of the lanthanide–electrochemical performance relationship is provided and will also inspire the rational design of efficient nanoscale RE alloy electrocatalysts.