Interface engineering of Ru/RuO ₂ heterostructures on carbon nanotubes for efficient and stable acidic oxygen evolution

Efficient and durable oxygen evolution reaction (OER) electrocatalysts are critical for enhancing proton exchange membrane water electrolyzer (PEMWE) performance. RuO₂ has high intrinsic OER activity, but it is susceptible to oxidation into soluble RuO₄^- species in acidic electrolytes due to the highly reactive nature of lattice oxygen. Herein, we introduce an effective strategy aimed at bolstering structural stability by constructing Ru/RuO₂ heterostructures onto carbon nanotubes (Ru/RuO₂@CNT). The formation of Ru⁰-O-Ru⁴⁺ interfacial structures within these heterostructures effectively suppresses the Ru⁴⁺ oxidation state and simultaneously refines the d-band center of Ru sites for optimizing the adsorption of intermediates, thus accelerating the OER kinetics. Consequently, Ru/RuO₂@CNT-300 achieves a low overpotential of 169 mV at 10 mA cm^-2 and displays remarkable durability exceeding 100 hours of stable operation in 0.5 M H₂SO₄. The unique structure endows Ru/RuO₂@CNT-300 with exceptional acidic OER activity compared to most reported electrocatalysts. This work provides a feasible pathway for designing efficient and stable OER electrocatalysts for high-performance PEMWE.