Facile fabrication of Mn-N doped porous carbon nanocages with enhanced oxygen reduction reaction activity

Mn-based oxygen reduction reaction (ORR) catalysts have high expectations, but cost and stability have always been the key problems to be solved in their industrialization. Herein, a novel electrocatalyst consisted of Mn-N-x doping sites within carbon frameworks was fabricated through a simple thermal and pickling treatment. The catalyst showed well-defined nanocage structure and excellent ORR performance with a half-wave potential of 0.85 V and a current density of 6 mA cm-(2 )- these values are comparable to most Mn-based catalysts and commercial Pt/C. The unique advantages of the catalyst are facile procedure, low cost and good stability. The activities of the possible active sites in Mn-NPC (N doped porous carbon) were compared using theoretical calculations and recent experimental evidence, and the results showed that Mn-N5 moiety has lower free energy barrier and higher oxygen adsorption performance than Mn-N-4 and Mn-N3 moieties to accelerate the ORR kinetics, which is of great significance for the subsequent design and directional synthesis of Mn-based catalysts.