La-Doping-Induced Lattice Strain and Electronic State Modulation in RuO 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 RuO in acidic media. The introduction of La into RuO 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 RuO. Meanwhile, La doping modulates the electronic structure of RuO and optimizes the adsorption energy of the reaction intermediates, thereby enhancing the electrocatalytic OER activity. Notably, the optimized La-RuO electrocatalyst presents an excellent OER performance in 0.5 M HSO electrolyte, which delivers a low overpotential of 190 mV at 10 mA cm and sustains 150 h without obvious decay at 50 mA cm. More importantly, a PEM electrolyzer is constructed by using our La-RuO as the anode catalyst, which acquires 200 h stability at 1 A cm, highlighting its strong potential for practical industrial applications. This work sheds new light on designing high-performance OER catalysts toward PEM electrolyzer applications.