Synergizing ruthenium oxide with bimetallic Co₂CrO₄ for highly efficient oxygen evolution reaction

Designing efficient and stable oxygen evolution reaction (OER) catalyst is the basis for the development of sustainable electrolytic water energy techniques. In this work, we presented a heterogeneous-structured electrocatalyst composed of bimetallic oxides-modified RuO₂ nanosheets supported on nikel foam (Co₂CrO₄/RuO₂) using a hybrid hydrothermal, ion-exchange and calcination method. The unique synergy and interfacial coupling between Co₂CrO₄/RuO₂ heterostructures are favorable for optimizing the electronic configuration at this interface and strengthening the charge transport capacity, thus strengthening the catalytic activity of the Co₂CrO₄/RuO₂ catalyst. The experimental data demonstrate that Cr leaching facilitates the rapid reconstruction of the catalyst into oxyhydroxides (CoOOH), which are acknowledged to be the real active species of OER. Theoretical calculations show that the Co₂CrO₄/RuO₂ heterostructure increases the density state at the Fermi energy level and lowers the d-band center, thereby strengthening the catalytic activity. The synthesized Co₂CrO₄/RuO₂ catalyst exhibited OER performance with an overpotential of 209 mV at 10 mA cm^-2 and displayed a low Tafel slope of 78.2 mV dec^-1, which outperforms most reported advanced alkaline OER catalysts. This work contributes to a new tactic for the design and development of ruthenium oxide/bimetallic oxides electrocatalysts.