Controlled synthesis of mesoporous carbon with ultra-high N‐doping structure from polymer precursor for efficient electrocatalysis of oxygen reduction

Abstract

A mesoporous carbon catalyst with ultra-high nitrogen-doping has been fabricate by a three-step process (including simple polycondensation of precursor between melamine and formaldehyde, carbonization process, and subsequent removal of template) to achieve efficient catalysis of oxygen reduction reaction (ORR). To decrease loss of N-doping in the carbonization process, two ionic compounds (ferric ammonium oxalate (FAO) and MgO) were added into the precursor, leading to the N content of the prepared catalysts (Fe-N-MCs) reached 23.91 at.%. Additionally, the MgO nanoparticles were also employed as template: MgO were encapsulated with precursor in the carbonization process, and then mesopores formed due to removal of MgO by acid-treatment, leading to specific surface area and mesopore volume of Fe0.04-N-MC800 catalyst is 479.8 m2 g−1 and 0.38 cm3 g−1. The high N content of Fe0.04-N-MC800 promotes its unique electro-catalysis: onset potential of Fe0.04-N-MC800 is 0.98 V (vs. RHE); kinetic current densities (Jk) of Fe0.04-N-MC800 is 6.53 mA cm−2 at 0.6 V); the Fe0.04-N-MC800 has higher electrochemical catalysis and stability towards the possible crossover or poison effects of ORR than commercial 20% Pt/C catalyst (Jk: 2.93 mA cm−2 at 0.6 V).