Dopant-induced electronic state modulation of ruthenium oxide for enhanced acidic oxygen evolution reaction

[Display omitted] •Corrosion-resistive TiO2 supported Co-doped RuO2 nanoparticles is prepared.•Co-RuO2/TiO2 exhibits excellent OER activity and stability in 0.5 M H2SO4.•Electron transfer from Co to Ru suppresses RuO2 oxidation enhancing its stability.•Co dopant also improves RuO2 activity by induced electronic modulation effect. The design of durable and high-efficiency acidic oxygen evolution reaction (OER) electrocatalysts for proton exchange membrane water electrolyzer (PEMWE) remains a challenging task. Herein, TiO2 supported Co-doped RuO2 nanoparticles (Co-RuO2/TiO2) were prepared as acidic OER electrocatalyst. Experimental characterization and theoretical analysis demonstrate that Co dopant induced electron redistribution and down shifting of d-band center of surface Ru sites in RuO2. This weakens the adsorption of oxygen intermediate on Co-RuO2/TiO2 and facilitates the rate-determining *OOH formation step, which is responsible for significantly enhanced acidic OER reaction. The accelerated *OOH generation on Co-RuO2/TiO2 was also verified through in-situ infrared and in-situ Raman spectroscopy. Meanwhile, the Co dopant with low electronegativity donates electrons to Ru in Co-RuO2/TiO2, which suppresses the over oxidation of Ru, and thus favoring the enhancement of the catalyst stability. Moreover, TiO2 with robust acid resistant can further enhance the catalyst stability. As a result, Co-RuO2/TiO2 shows excellent OER activity with an overpotential of 266 mV at 10 mA cm−2 and a mass activity of 518.1 A/gRu at 1.5 V vs RHE, which is nearly 30 times higher than that of commercial RuO2. Almost no current degradation is observed after 50 h stability test in 0.5 M H2SO4, showing the superior stability of Co-RuO2/TiO2. This work provides an insightful electronic state modulation strategy for strengthening the activity and durability of acidic OER catalysts.