Pyridinic nitrogen exclusively doped carbon materials as efficient oxygen reduction electrocatalysts for Zn-air batteries

Rational design a metal-free catalyst with well-defined structure as alternative of noble metal is highly desirable but challenging to catalyze oxygen reaction for metal-air batteries. In this report, nitrogen with a specific configuration is selectively doped into the carbon skeleton to prepare a graphdiyne-like carbon material, in which one carbon atom in every benzene ring of graphdiyne (GDY) is substituted by pyridinc N (PyN-GDY). Composed by pyridine ring and acetylenic linkers, the PyN-GDY is prepared through a bottom-up strategy using pentaethynylpyridine as the monomer. The as-synthesized PyN-GDY with "defined" molecular structure is an ideal model for addressing the intrinsic activity of active sites at molecular level. It exhibits excellent performance in both alkaline and acidic media as electrochemical catalyst for oxygen reduction reaction (ORR). The PyN-GDY-based Zn-air battery is demonstrated more active and stable than commercial Pt/C-based battery. Density functional theory calculations are used to analyze and determine the possible active sites of PyN-GDY in ORR. The precise construction of specific nitrogen doped carbon material is an effective method to produce efficient catalysts for electrocatalysis.