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) Fe3O4 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 Fe3O4 NCs with exposed high-energy {110} surfaces might be the result of selective stabilization of such unstable facets by the C17H33COO- based on FT-IR analysis. The magnetic measurement revealed that the saturation magnetization (M-s) of the RD Fe3O4 NCs was 85 emu/g at room temperature. When used as peroxidase mimetics, the prepared RD Fe3O4 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 H2O2. When tested as anode materials for lithium-ion batteries, these as-obtained RD Fe3O4 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.