Porous Co@NC Materials Obtained by Pyrolyzing Metal-Organic Framework-Supported Multinuclear Metal Clusters for the Oxygen Reduction Reaction

The design and development of efficient oxygen reduction reaction (ORR) electrocatalysts have become a key challenge for fuel cells and metal-air batteries. As a cutting-edge field in electrocatalysis, single-atom catalysts have been widely used in ORR due to their maximum atomic utilization and tunable coordination environment. In this study, multinuclear metal clusters were selected as precursors to construct metal nanoparticles and single-atomic metal sites doped carbon materials for electrocatalytic ORR. Specifically, Co-based metal clusters Co₄O₄ were prepared as precursors and Zn-based zeolitic imidazolate frameworks ZIF-8 were selected as supports. The resulting metal Co-supported nitrogen-doped carbon (Co@NC) materials were obtained by pyrolyzing ZIF-8-Co₄O₄ hybrids. Both Co nanoparticles and single-atomic Co–N₄ sites were observed on porous NC supports. Porous structures were attributed to the departure of Zn and O at the high-temperature. Co@NC catalyst exhibits a half-wave potential of 0.86 V (vs. reversible hydrogen electrode, vs. RHE) for the ORR measured in a 0.1 M KOH solution. This work provides a new idea for constructing single-atomic catalysts for electrocatalysis using multinuclear metal clusters as active sites.