Synthesis of efficient electrocatalyst for oxygen reduction reaction by using poly(m-phenylenediamine) as the interlayer spacer and the sources of N-doped carbon and MnO

- A facile strategy for the fabrication of efficient ORR electrocatalyst is proposed.
- Poly(m-phenylenediamine) shows multiple functions in preparing ORR electrocatalyst.
- The ORR catalyst exhibits excellent ORR activity, durability and methanol tolerance.
- The ORR activity of the obtained catalyst is even better than that of the 5% Pt/C.
- It would benefit the development of doped graphene catalysts for energy conversion.

We report the facile synthesis of N-doped carbon-graphene-manganese oxide (N/C-G-MnO) that can serve as precious metal-free electrocatalysts for oxygen reduction reaction (ORR). The N/C-G-MnO is synthesized via polymerization of m-phenylenediamine adsorbed on graphene using KMnO4 as the oxidant, followed by pyrolyzation of the resulting N- and MnO2-containing poly(m-phenylenediamine). That is, poly(m-phenylenediamine) plays multi-roles in the synthesis of the ORR catalysts: (i) Serving as interlayer spacer to prevent graphene sheets from restacking during the thermal annealing, (ii) Function as the source of N-doped carbon (N/C) and MnO for the simultaneous doping of graphene. The N/C-G-MnO exhibits better ORR activity, long-term stability and methanol tolerance than those of the commercial Pt (5%)/C catalyst.

Poly(m-phenylenediamine) plays a crucial role in the synthesis of N-doped carbon-graphene-MnO (N/C-G-MnO), since it can effectively inhibit the restacking of graphene during the thermal annealing and serve as the source of N/C and MnO. Due to the synergistic effect of N/C, graphene and MnO, the N/C-G-MnO electrocatalyst exhibits excellent ORR activity, durability and tolerance to methanol crossover effect.112