Ultrasmall Strained RuO2 as a Highly Efficient Electrocatalyst for Acidic Oxygen Evolution Reaction

The development of noniridium electrocatalysts toward acidic oxygen evolution reaction (OER) is essential for designing efficient proton-exchange-membrane water electrolyzers (PEMWEs) for hydrogen production. Ruthenium oxide has long been expected as a promising candidate but still suffers from inadequate durability. Here we deploy a strain engineering strategy to improve the OER performance. Density functional theory calculations demonstrate that introducing tensile strain into the RuO2 lattice can concurrently optimize the adsorption behavior and enhance the structural stability. Experimentally, we successfully synthesized tensile-strained RuO2 nanoparticles via a graphene oxide confinement method. This catalyst exhibits a low-record overpotential of 136 mV and a high durability over 160 h at 10 mA cm-2 in acidic media. When integrated into a PEMWE device, an exceptional water splitting performance is achieved with a large current density of 3.45 A cm-2 at 1.8 V and a long-term operation at 0.2 A cm-2 for 120 h, suggesting its potential for practical applications.