Metallic Ni3N nanosheets with exposed active surface sites for efficient hydrogen evolution

Atomically thin metallic Ni3N nanosheets fabricated as the hydrogen evolution cathode exhibit remarkable HER activity close to that of a commercial Pt/C electrode. The Ni atoms accompanied by surrounding N atoms on the N–Ni surface demonstrate a small ΔGH* of 0.065 eV due to the Ni–N co-effect, and thus act as the most active HER sites.