MOFs fertilized transition-metallic single-atom electrocatalysts for highly-efficient oxygen reduction: Spreading the synthesis strategies and advanced identification

Metal-organic frameworks (MOFs) have been widely used in oxygen reduction reaction (ORR) of fuel cells and metal-air batteries, attributed to their unique structures and compositions. Recently, the preparation of transition-metallic single-atom electrocatalysts (TM-SACs) using MOFs as precursors or templates has made great progress. Herein, the development history of SACs prepared based on MOFs and their characterization are overviewed firstly, and then several strategies are summarized for preparing TM-SACs using MOFs and further modification. Finally, the challenges and opportunities confronted by TM-SACs are fully discussed. Consequently, our work can guide the realization of TM-SACs abundant with high activity, high loading and high stability.