A Versatile Synthesis Route for Atomically Dispersed Metal Nanoparticles on Nitrogen-doped Porous Carbon Supports

Metal nanoparticles (MNPs) have a wide range of applications in heterogeneous catalysis, electronics, sensors, and optics. However, MNPs are unstable due to the high surface energy, so aggregation occurs, which nullifies any benefits associated with the reduced particle size. To overcome this propensity, MNPs are often loaded onto porous supports, which offer many advantages including a significant boost in particle dispersion and reactive surface area, thereby improving the efficiency of MNPs. The activity of MNPs is largely attributed to the reduced particle size because the amount of reactive sites increases with decreasing particle size. For this reason, an enormous attention has been devoted to decreasing the particle size of MNPs. Although metal nanoparticles exist in small aggregates ranging in size from 10 to 50 nm, the achievement of atomic metal dispersion is a big challenge. Herein, we report a novel single-step synthesis of atomically dispersed transition metals on carbon spheres. The in-situ approach utilizes the chelating ability of polydentate ligands to form cage-like complexes around metal centers. The chelated complex confines the metal atom, which effectively prevents aggregation even at high metal concentrations. Since chelating agents have unusually large formation constants with most transition metals; the atomically dispersed metal nanoparticles can be synthesized for a wide range of metals