Inducing two-dimensional single crystal TiN arrays with exposed {1 1 1} facets by a novel chemical vapor deposition with excellent electrocatalytic activity for hydrogen evolution reaction

Two-dimensional (2D) single crystal transition metal nitrides (TMNs) with exposed active crystal planes have great value for fundamental science and technological applications. However, it is still a great challenge to synthesize the non-layer crystal structured 2D single crystal TMNs, e.g. the face-centered cubic (FCC) 2D single crystal TiN, which would have distinct properties. Herein, for the first time, an induction-inhibition strategy was successfully developed to break through the intrinsic limitation and the weak anisotropic growth tendency of the FCC TiN. Single-crystalline TiN nanosheet (about 5.14 nm thickness) arrays with exposed {1   1   1} active facets were synthesized successfully on a large scale by the new strategy, where the layer arrays were induced by a layered TiNCl intermediate formed by the chemical vapor deposition reaction of a new titanium source (TiCl 3 ) with NH 3 and the exposed {1   1   1} facets was caused by the chemisorbed Cl inhibitor. The special 2D single crystal TiN arrays exhibited excellent catalytic activity and durability for hydrogen evolution reaction (HER) from water electrolysis.