Constructing Interfacial Oxygen Vacancy and Ruthenium Lewis Acid-Base Pairs to Boost the Alkaline Hydrogen Evolution Reaction Kinetics.

Simultaneous optimization of the energy level of water dissociation, hydrogen and hydroxide desorption is the key to achieving fast kinetics for the alkaline hydrogen evolution reaction (HER). Herein, the well-dispersed Ru clusters on the surface of amorphous/crystalline CeO2-δ (Ru/ac-CeO2-δ ) is demonstrated to be an excellent electrocatalyst for significantly boosting the alkaline HER kinetics owing to the presence of unique oxygen vacancy (VO ) and Ru Lewis acid-base pairs (LABPs). The representative Ru/ac-CeO2-δ exhibits an outstanding mass activity of 7180 mA mgRu -1 that is approximately 9 times higher than that of commercial Pt/C at the potential of -0.1 V (V vs RHE) and an extremely low overpotential of 21.2 mV at a geometric current density of 10 mA cm-2 . Experimental and theoretical studies reveal that the VO as Lewis acid sites facilitate the adsorption of H2 O and cleavage of H-OH bonds, meanwhile, the weak Lewis basic Ru clusters favor for the hydrogen desorption. Importantly, the desorption of OH from VO sites is accelerated via a water-assisted proton exchange pathway, and thus boost the kinetics of alkaline HER. This study sheds new light on the design of high-efficiency electrocatalysts with LABPs for the enhanced alkaline HER.