Ru-W Pair Sites Enabling the Ensemble Catalysis for Efficient Hydrogen Evolution.

Simultaneously optimizing elementary steps, such as water dissociation, hydroxyl transferring, and hydrogen combination, is crucial yet challenging for achieving efficient hydrogen evolution reaction (HER) in alkaline media. Herein, Ru single atom-doped WO 2 nanoparticles with atomically dispersed Ru-W pair sites (Ru-W/WO 2 -800) are developed using a crystalline lattice-confined strategy, aiming to gain efficient alkaline HER. It is found that Ru-W/WO 2 -800 exhibits remarkable HER activity, characterized by a low overpotential (11 mV at 10 mA cm -2 ), notable mass activity (5863 mA mg -1 Ru at 50 mV), and robust stability (500 h at 250 mA cm -2 ). The highly efficient activity of Ru-W/WO 2 -800 is attributed to the synergistic effect of Ru-W sites through ensemble catalysis. Specifically, the W sites expedite rapid hydroxyl transferring and water dissociation, while the Ru sites accelerate the hydrogen combination process, synergistically facilitating the HER activity. This study opens a promising pathway for tailoring the coordination environment of atomic-scale catalysts to achieve efficient electro-catalysis.