Interface Inversion: A Promising Strategy to Configure Ultrafine Nanoparticles over Graphene for Fast Sodium Storage

Due to the merits of high activity and rapid reaction kinetics, ultrafine nanoparticles loaded on conductive scaffolds are of great potential in energy-related fields. Usually, the nucleation and uniform growth of these active nanoparticles in high density on scaffolds is governed by the local ion concentration gradient and nucleation sites at the interfaces. On account of this, a novel interface-inverting strategy is developed to modulate the diffusion of metal ions toward the nucleation sites, leading to the tuned growth of ultrafine nanoparticles anchored on graphene. Typically, the Ni(OH)₂ deposited on graphene initially enables the interface inverting from oil-water-solid consisting of liquid paraffin (LP), water, and GO to water-oil-solid, finally resulting in LP-enveloped Ni(OH)₂ /GO structure. In response, the inert-infiltrated LP layer inhibits the solubility and diffusion of nickel ions, which functions to modulate the growth and aggregation of adjacent nanoparticles. As a demonstration, the phosphorized Ni₂ P@C/G as anode in sodium-ion capacitor can deliver a high energy density of 54 Wh kg^-1 at a high power density of 23 kW kg^-1 yet with a remarkable rate performance due to the surface-enhanced energy storage and fast Na⁺ transport enabled by the tuned surface/interface.