Bulk and Surface Dual-Modification for Stabilizing RuO₂ Anode in 2 A cm^-2 PEMWE Operation.

Abstract

RuO₂ is a promising alternative to IrO₂ for the oxygen evolution reaction (OER) in proton exchange membrane water electrolyzers (PEMWEs). However, to date, only Ir oxide or IrRu-oxide based anodes have demonstrated possible stable operation at industrial-relevant current densities of 2 A cm^-2 for practical PEMWE applications. The poor durability of Ir-free RuO₂ anodes remains a major barrier to its practical use. While metal doping has been extensively explored to stabilize the Ru valence, emerging evidence suggests a multifactorial failure mechanism involving both physical and chemical degradation of RuO₂ anodes. This underscores the need for strategies that stabilize both the catalyst bulk structure and reaction interface in OER. Here, we report a dual-modification strategy combining bulk Cr substitution with Si surface modification to simultaneously enhance the intrinsic activity and stability of RuO₂-based anode in PEMWE. Cr doping modulates the Ru valence state in the bulk phase, promoting charge transfer while suppressing Ru overoxidation, whereas Si modification stabilizes the reaction interface by inhibiting catalyst reconstruction and protecting the Cr dopant. The resulting catalyst achieves stable operation in PEMWE at 2 A cm^-2 and 1.65 V. This work provides new insights into the development of RuO₂-based catalysts and electrodes for PEMWEs.