Cascade-Welding Strategy to Anchor Atomic Iron Metal Sites on Superstructured Porous Carbons for both Organic...

Atomic single metal sites riveted on carbon materials have drawn ever-growing interest in various electrocatalytic and inorganic transformation processes owing to their exceptional catalytic performance and selectivity. However, there are challenges for the generic and controlled fabrication of such catalysts. Herein, a general, flexible and versatile cascade-locking route is developed to construct metal single atom sites on hierarchical nitrogen-doped superstructured carbons (M SAs-N/SC) via pyrolysis of a unique metallo-supramolecular organic framework precursor, in which primary metal complexes of 2, 2'-bicinchoninic acid (BCA) and target metal ions using metal-N coordination bonds are ulteriorly crosslinked with melamine (MA) units through intramolecular N─H∙∙∙O and O─H∙∙∙N hydrogen bond interactions. Importantly, a series of atomic-level metal site catalysts can be successfully fabricated, demonstrating the remarkable adjustability and generality of this method. When acting as a heterogeneous catalyst in C-H oxidation and alkene epoxidation reactions, such Fe SAs-N/SC exhibited high selectivity, reusability, and substrate tolerance. Moreover, the as-prepared Fe SAs-N/SC catalyst delivered exceptional catalytic performance for the electrocatalytic CO₂ reduction reaction. The finding puts forward a brand-new and universal way to synthesize single atom metal site catalysts for a wide range of potential applications.