Oxygen-Coordinated Single-Atom Nickel Catalysts Derived from Water-Induced Metal-Organic Framework Aerogel for...

Research on metal-organic framework (MOF) aerogels is relatively scarce, primarily constrained by the limited availability of synthetic methods. Herein, a water-induced rapid conversion process of MOF powder to MOF aerogel is demonstrated, where the macroscopic transition is essentially due to the reassembly of microscopic constituent units and the rapid alteration of morphological structure. The derived catalyst possesses abundant holes left by the acid leaching process, leading to the high enrichment of O-coordinated single-atom Ni sites on the concomitant carbon edges. Consequently, such a catalyst exhibits excellent catalytic activity for oxygen evolution reaction (OER) in alkaline media, only requiring a low overpotential of 279 mV to drive the benchmark current density of 10 mA cm^-2. Density functional theory calculations further reveal the reduced OER energy barrier over the edge-enriched O-coordinated single-atom Ni sites, as compared with internal O-coordinated sites and traditional N-coordinated sites. This is primarily attributed to the optimization effect of distinctive O-coordinated structure and synergistic edge effect on the electronic structure of active Ni centers.