Synthesis of Rhombic Dodecahedral Fe3O4 Nanocrystals with Exposed High-Energy {110} Facets and Their Peroxidase-like Activity and Lithium Storage Properties

Large quantities of monodispersed single-crystal rhombic dodecahedral (RD) Fe 3 O 4 nanocrystals (NCs) bounded by high-energy {110} facets were prepared by using a one-pot toluene–water two-phase interfacial reaction method. By adjusting the Fe(acac) 3 concentration and the volume of hydrazine hydrate, their sizes could be controlled in the range from 60 to 100 nm. The formation of these RD Fe 3 O 4 NCs with exposed high-energy {110} surfaces might be the result of selective stabilization of such unstable facets by the C 17 H 33 COO – based on FT-IR analysis. The magnetic measurement revealed that the saturation magnetization ( M s ) of the RD Fe 3 O 4 NCs was 85 emu/g at room temperature. When used as peroxidase mimetics, the prepared RD Fe 3 O 4 NCs showed excellent peroxidase-like catalytic activity toward oxidation of the substrate 3,3′,5,5′-tetramethylbenzidine and degradation of the aniline compound methylene blue dye in the presence of H 2 O 2 . When tested as anode materials for lithium-ion batteries, these as-obtained RD Fe 3 O 4 NCs showed a high initial discharge capacity of 1147 mA h g –1 at the current density of 0.2 C, a good cycle performance (362 mA h g –1 at 0.2 C after 100 cycles and 191 mA h g –1 at 1 C up to 130 cycles), and good rate capability at high current rates of 1–4 C.