Dopant-Free Stabilization of Ruthenium Oxide via Metallic Ru-Induced d-Orbital Modulation for Acidic Water Electrolysis

Abstract

Proton exchange membrane water electrolysis (PEMWE) is a cornerstone technology for carbon-neutral hydrogen production, yet its scalability is constrained by the intrinsic activity-stability trade-off of oxygen evolution reaction (OER) electrocatalysts. To overcome this challenge, we design a Ru/RuO2 heterostructure by integrating metallic Ru to modulate the d-orbital electron density of RuO2. The metallic Ru domains suppress lattice oxygen migration (LOM) while enhancing electron delocalization. The eg orbital filling shifts the Ru 4d-band center downward, reducing the adsorption strength of reaction intermediates (*OH, *O, *OOH). The optimized Ru/RuO2 electrocatalyst achieves a overpotential of 181 mV at 10 mA cm-2 in 0.5 M H2SO4 and maintains stable performance for 260 hours with minimal degradation rate (0.065 mV h-1). In PEMWE device, it lowers the cell voltage from 1.88 V (RuO2) to 1.68 V (Ru/RuO2) at 1 A cm-2, exhibiting negligible performance loss over 120 hours. This work introduces a dopant-free electronic engineering strategy that advances the design of stable, high performance pure Ru-based anodic catalysts for energy conversion technologies.