Ni W -W Interconnected Hybrid Prepared by Atmosphere- and Thermal-Induced Phase Separation for Efficient Electrocatalysis of Alkaline Hydrogen Evolution.

The development of efficient and stable noble-metal-free electrocatalysts for hydrogen evolution reaction (HER) in alkaline media is still a challenge. Herein, a hybrid material formed by the interconnection of Ni W intermetallic compound with metallic W is demonstrated for HER. The Ni W -W hybrid is prepared by the atmosphere- and thermal-induced phase-separation strategy from a single-phase precursor (NiWO ), which gives Ni W -W hybrid abundant and tight interfaces. The theoretical calculation manifests that Ni W shows more optimized energetics for adsorbed H atom, while W has lower energy barrier for water dissociation, and the synergistic effect between them is believed to facilitate the HER kinetics. Moreover, Ni W presents a proper adsorption strength for both adsorbed OH and H, and thus Ni W may also act as a high HER catalyst by itself. As a result, the Ni W -W hybrid demonstrates high activity and durability for HER in liquid alkaline electrolyte; the electrolyzer assembled by Ni W -W hybrid and Ni-Fe-layered double hydroxide (LDH) as, respectively, the cathode and anode electrocatalysts presents superior performance to Pt/C-IrO benchmark. In addition, the Ni W -W hybrid also works well in the water electrolyzer based on solid hydroxide exchange membrane. The present work provides a promising pathway to the design of high-performance electrocatalysts.