Manganese, nitrogen co-doped porous carbon with high-loading active sites as the oxygen reduction catalyst for Zn–air batteries

Abstract

Manganese–nitrogen–carbon (Mn–N–C) materials have been considered ideal catalysts for the oxygen reduction reaction (ORR). However, avoiding metal agglomeration during pyrolysis while ensuring the construction of Mn–N_x active centers is still difficult. Furthermore, the influence of pyrolysis temperature on structures of Mn–N–C is controversial, and needs an in-depth understanding. Herein, we prepare single atom Mn–N–C via a spatial confinement method. This is achieved through the pyrolysis of the ZIF precursor, where single Mn(acac)₃ molecules are trapped within its cavities. Compared with 800 °C and 1000 °C, 900 °C is the optimal pyrolysis temperature for the synthesis of ZIF-derived Mn–N–C, which promotes the formation of the porous framework and dense Mn–N_x centers (27.47%). As a result, Mn–N–C-900 possesses an outstanding performance with a half-wave potential (E_1/2) of 0.882 V in alkaline media. Impressively, the Zn–air battery using Mn–N–C-900 delivers a high peak power density of 84 mW cm⁻².