LAUSR

Abstract Hampered by the ambiguous mechanism of hydrogen evolution reaction (HER) in basic media, the exploration of highly efficient catalytically active sites for alkaline HER is of significance. Herein, a metal oxide Sr4Ru2O9 engineering a face-sharing [RuO6] octahedra motif was synthesized through the solid-state method, and served as HER electrocatalyst. Benefited from the Ru-Ru metallic bonding crossing the common plane, the H* adsorption and reaction energy barriers were optimized. Sr4Ru2O9 only required an ultra-small overpotential (ƞ10) of 28 mV at a current density of 10 mA cm−2 for HER in 1.0 M KOH with an exceptional stability (180 hours), outperforming the commercial Pt/C (ƞ10 = 38 mV). These findings suggest a fresh insight in designing novel active sites for electrocatalysis.