A Universal Strategy toward Ultrasmall Hollow Nanostructures with Remarkable Electrochemical Performance

Abstract

A facile and versatile microwave-assisted and shell-confined Kirkendall diffusion strategy is used to fabricate ultrasmall hollow nanoparticles by modulating the growth and thermal conversion of metal-organic framework (MOF) nanocrystals on graphene. This method involves that the adsorption of microwave by graphene creates a high-energy environment in a short time to decompose the in situ grown MOF nanocrystals into well-dispersed uniform core-shell nanoparticles with ultrasmall size. Upon a shell-confined Kirkendall diffusion process, hollow nanoparticles of multi-metal oxides, phosphides, and sulfides with the diameter below 20 nm and shell thickness below 3 nm can be obtained for the first time. Ultrasmall hollow nanostructures such as Fe2O3 can promote much faster charge transport and expose more active sites as well as migrate the volume change stress more efficiently than the solid and large hollow counterparts, thus demonstrating remarkable lithium-ion storage performance.

Keywords: Kirkendall effect; hollow nanostructures; lithium-ion batteries; microwave-assisted synthesis; size effect.