Activating ruthenium dioxide via compressive strain achieving efficient multifunctional electrocatalysis for Zn‐air batteries and overall water splitting

Surface strain engineering is a promising strategy to design various electrocatalysts for sustainable energy storage and conversion. However, achieving the multifunctional activity of the catalyst via the adjustment of strain engineering remains a major challenge. Herein, an excellent trifunctional electrocatalyst (Ru/RuO2@NCS) is prepared by anchoring lattice mismatch strained core/shell Ru/RuO2 nanocrystals on nitrogen‐doped carbon nanosheets. Core/shell Ru/RuO2 nanocrystals with ~5 atomic layers of RuO2 shells eliminate the ligand effect and produce ~2% of the surface compressive strain, which can boost the trifunctional activity (oxygen evolution reaction [OER], oxygen reduction reaction [ORR], and hydrogen evolution reaction [HER]) of the catalyst. When equipped in rechargeable Zn‐air batteries, the Ru/RuO2@NCS endows them with high power (137.1 mW cm−2) and energy (714.9 Wh kgZn−1) density and excellent cycle stability. Moreover, the as‐fabricated Zn‐air batteries can drive a water splitting electrolyzer assembled with Ru/RuO2@NCS and achieve a current density of 10 mA cm−2 only requires a low potential ~1.51 V. Density functional theory calculations reveal that the compressive strained RuO2 could reduce the reaction barrier and improve the binding of rate‐determining intermediates (*OH, *O, *OOH, and *H), leading to the enhanced catalytic activity and stability. This work can provide a novel avenue for the rational design of multifunctional catalysts in future clean energy fields. Lattice strain were induced by the in‐situ heteroepitaxial growth of lattice‐mismatched RuO2 shell layer grows coherently on the stretchable Ru core. RuO2 activated by compressive strain simultaneously enhances the electrocatalytic OER, ORR, and HER. Zinc‐air batteries and water splitting devices assembled using the strained RuO2 as electrode electrocatalysts also shows excellent operation performance.