Nitrogen/Cobalt Co‐doped Mesoporous Carbon Microspheres Derived from Amorphous Metal‐Organic Frameworks as a Catalyst for the Oxygen Reduction Reaction in Both Alkaline and Acidic Electrolytes

Abstract

AbstractNitrogen/cobalt co‐doped carbon (Co/N−C) catalysts are the best candidates to replace their Fe‐based analogues for the oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs), owing to the absence of radical‐induced PEMFC membrane/ionomer degradations that are commonly encountered in the Fe/N−C system. Herein, we present an amorphous Co‐metal organic framework (MOF) route for the fabrication of N/Co co‐doped mesoporous carbon spheres by directly pyrolyzing amorphous Co‐MOF microspheres. The as‐synthesized Co/N−C‐800 catalyst (heat‐treated at 800 °C) has a unique spherical architecture with short nanotubes on its surface and simultaneously possesses a relatively large Brunauer‐Emmett‐Teller surface area (381 m2 g−1) and a high N content (4.95 at%). Owing to these benefits, the Co/N−C‐800 catalyst displays good ORR performance in both alkaline and acidic electrolytes, that is, the ORR onset potential (Eo), half‐wave potential (E1/2), and current density at 0.4 V (vs. RHE, J@0.4) are 0.981 V (vs. RHE), 0.872 V (vs. RHE), and 5.47 mA cm−2, respectively, in alkaline media, and 0.863 V (vs. RHE), 0.707 V (vs. RHE), and 5.29 mA cm−2, respectively, in acidic electrolyte. More importantly, the Co/N−C‐800 catalyst also exhibits excellent poison tolerance in acidic electrolytes.