La-Doping-Induced Lattice Strain and Electronic State Modulation in RuO2 for Electrocatalytic Oxygen Evolution in Acidic Solutions

Pursuing highly active and stable Ru-based catalysts for the oxygen evolution reaction (OER) under acidic conditions is important in advancing proton exchange membrane (PEM) water electrolyzers. Unfortunately, the inadequate stability, especially under a large current density of Ru-based catalysts, still hinders its practical application. Herein, we report a La doping strategy that simultaneously enhances both OER activity and stability of RuO₂ in acidic media. The introduction of La into RuO₂ induces tensile strain, which effectively weakens the covalency of Ru-O bonds. This structural modification significantly inhibits Ru dissolution, thereby substantially enhancing the stability of RuO₂. Meanwhile, La doping modulates the electronic structure of RuO₂ and optimizes the adsorption energy of the reaction intermediates, thereby enhancing the electrocatalytic OER activity. Notably, the optimized La_0.05-RuO₂ electrocatalyst presents an excellent OER performance in 0.5 M H₂SO₄ electrolyte, which delivers a low overpotential of 190 mV at 10 mA cm^-2 and sustains 150 h without obvious decay at 50 mA cm^-2. More importantly, a PEM electrolyzer is constructed by using our La_0.05-RuO₂ as the anode catalyst, which acquires 200 h stability at 1 A cm^-2, highlighting its strong potential for practical industrial applications. This work sheds new light on designing high-performance OER catalysts toward PEM electrolyzer applications.