Highly effective dual transition metal macrocycle based electrocatalyst with macro-/mesoporous structures for oxygen reduction reaction

Abstract

Metal macrocycle based non-noble metal electrocatalysts (NNMEs) with highly efficient oxygen reduction reaction (ORR) activity, good stability, and excellent resistance to the methanol cross-over effect have been regarded as one of the most important alternatives for Pt or Pt based alloys, which are widely used in fuel cells. However, the expensive price of most metal macrocycles hinder further investigation of such a family of NNMEs in large production for practical applications. Here, we introduce a simple strategy to synthesize metal macrocycle based porous carbon (MMPC) material with low cost and easy production of metal macrocycles (hemin (Hm) and vitamin B12 (VB12)) as raw materials by using a hard template of MgO. The pyrolysis of MMPC under the optimal temperature at 900 °C shows comparative ORR performance relative to commercial Pt/C, which could be attributed to the large surface area, macro-/mesoporous structure, the carbon layer encapsulating transition metal based oxides, as well as N-doped carbon species. In addition, MMPC (900) displays a better electrochemical property than 20 wt % Pt/C in terms of durability and tolerance to methanol in O2-saturated 0.1 M KOH media.