Atmospheric‐Pressure Synthesis of 2D Nitrogen‐Rich Tungsten Nitride

Abstract 2D transition metal nitrides, especially nitrogen‐rich tungsten nitrides (W x N y , y > x ), such as W 3 N 4 and W 2 N 3 , have a great potential for the hydrogen evolution reaction (HER) since the catalytic activity is largely enhanced by the abundant WN bonding. However, the rational synthesis of 2D nitrogen‐rich tungsten nitrides is challenging due to the large formation energy of WN bonding. Herein, ultrathin 2D hexagonal‐W 2 N 3 ( h ‐W 2 N 3 ) flakes are synthesized at atmospheric pressure via a salt‐templated method. The formation energy of h ‐W 2 N 3 can be dramatically decreased owing to the strong interaction and domain matching epitaxy between KCl and h ‐W 2 N 3 . 2D h ‐W 2 N 3 demonstrates an excellent catalytic activity for cathodic HER with an onset potential of −30.8 mV as well as an overpotential of −98.2 mV for 10 mA cm −2 .