Recent progress in the synthesis of transition metal nitride catalysts and their applications in electrocatalysis.

Transition metal nitrides (TMNs) have become excellent substitutes for precious metals such as Pt and Ir in the field of electrocatalysis because of their excellent electrocatalytic performance, high conductivity, good corrosion resistance and stability. As we all know, the commonly utilized carbon-based materials corrode easily during electrocatalysis, which will lead to catalyst falling off and agglomeration. Compared with carbon-based materials, TMNs have stronger corrosion resistance and higher stability. In the metal nitrides, a variety of chemical bonds (metal bond, ionic bond and covalent bond) coexist, among which the ionic bond between metal atoms and nitrogen atoms can make the d-band shrink and narrow, which leads to TMNs having characteristics similar to precious metals in the electrocatalytic process; thus, they can be used as a substitute for precious metal catalysts. In this paper, the synthesis method and catalytic principle of transition metal nitrides and their applications in the fields of hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) are discussed, and the shortcomings of TMNs as a catalyst, the challenges faced in catalyst research and the developments and prospects for the future are pointed out.