Rational Design of Hierarchical, Porous, Co-Supported, N-Doped Carbon Architectures as Electrocatalyst for Oxygen Reduction

Graphical Hierarchical electrocatalyst : Co-supported, N-doped, 3D-ordered porous carbon (Co-NOPC) is obtained by carbonization of the ordered porous metal–organic framework ZIF-67 prepared by forced molding of a polystyrene sphere (PS) template. The hierarchical porosity of Co-NOPC results in significantly improved performance as an electrocatalyst for the oxygen reduction reaction (ORR) under both alkaline and acidic conditions compared with its counterpart prepared from conventional ZIF-67. Developing highly active nonprecious-metal catalysts for the oxygen reduction reaction (ORR) is of great significance for reducing the cost of fuel cells. 3D-ordered porous structures could substantially improve the performance of the catalysts because of their excellent mass-diffusion properties and high specific surface areas. Herein, ordered porous ZIF-67 was prepared by forced molding of a polystyrene template, and Co-supported, N-doped, 3D-ordered porous carbon (Co-NOPC) was obtained after further carbonization. Co-NOPC exhibited excellent performance for the ORR in an alkaline medium with a half-wave potential of 0.86 V vs. reversible hydrogen electrode (RHE), which is higher than that of the state-of-the-art Pt/C (0.85 V vs. RHE). Moreover, the substantially improved catalytic performance of Co-NOPC compared with Co-supported, N-doped carbon revealed the key role of its hierarchical porosity in boosting the ORR. Co-NOPC also exhibited a close-to-ideal four-electron transfer path, long-term durability, and resistance to methanol penetration, which make it promising for large-scale application.