Monofacet-Selective Cavitation within Solid-State Silica-Nanoconfinement toward Janus Iron Oxide Nanocube

Abstract

In this study, a highly selective solid-state nanocrystal conversion strategy is developed toward concave iron oxide (conc-Fe3O4) nanocube with an open-mouthed cavity engraved exclusively on a single face. This strategy is based on the diffusion of Fe2+ ions from the Fe3O4-SiO2 interface to the surrounding silica shell by heat treatment in a nanoconfined system. The Janus-type concave iron oxide nanocube with chemically unique cavity was formed by the self-limiting phase transformation to the Fe-silicate form within silica-nanoconfined system followed by functionalizing with controllable density of catalytic Pt-nanocrystals exclusively on the concave sites. In a solution, synthesized Janus nanoparticle with asymmetric structure could be propelled by itself due to their structural nature, and be utilized as a highly diffusive catalytic nanoswimmer for the efficient decomposition of pollutant-dye in water.