Double‐Site Ni–W Nanosheet for Best Alkaline HER Performance at High Current Density >500 mA cm−2

Abstract

AbstractThe efficiency of the alkaline hydrogen evolution reaction (HER) has remained limited. Herein, a bimetallic Ni–W catalyst fabricated by the rapid dehydration of W‐doped Ni(OH)2 is reported. The Ni–W surface exhibits the following merits for an enhanced alkaline HER: a greater number of vacant outer d‐orbitals, better discharge characteristics, and a more significant difference in H adsorption between W and Ni atoms. The free water molecules are adsorbed onto W sites, then dissociated into *OH and *H. While *OH is released into the solution, *H is re‐adsorbed by nearby Ni sites. The synergistic effect of the Ni–W surface sites imparts this catalyst with the highest activity and the best stability at high current density. Specifically, at a current density of 500 mA cm‐2, the Ni–W catalyst reduces the overpotential to 303 mV, compared with 409 mV for the state‐of‐the‐art Pt/C catalyst. Additionally, the Ni–W catalyst exhibits better long‐term stability than the state‐of‐the‐art Pt/C. Whereas the Pt activity decreases by 181 mA cm‐2 after 31 h of testing at 500 mA cm‐2, the Ni–W loses only 55 mA cm‐2 under the same conditions. Density functional theory (DFT) calculations confirm the synergistic mechanism, which can be useful for general alkaline HER processes.