▎ 摘　　要

In this study, a one-step process to fabricate "Janus"-structured nano-composites with iron oxide (Fe3O4) nanoparticles (Fe3O4 NPs) and polydopamine (PDA) on each side of a graphene oxide (GO) nanosheet using the Langmuir-Schaefer technique has been proposed. The Fe3O4 NPs-GO hybrid is used as a high-capacity active material, while PDA is added as a binder due to its unique wet-resistant adhesive property. The transmission electron microscopy image shows a superlattice-like out-of-plane section of the multilayered nanocomposite, which maximizes the density of the composite materials. Grazing-incidence small-angle X-ray scattering results combined with scanning electron microscopy images confirm that the multilayered Janus composite exhibits an in-plane hexagonal array structure of closely packed Fe3O4 NPs. This Janus multilayered structure is expected to maximize the amount of active material in a specific volume and reduce volume changes caused by the conversion reaction of Fe3O4 NPs. According to the electrochemical results, the Janus multilayer electrode delivers an excellent capacity of similar to 903 mAh g(-1) at a current density of 200 mA g(-1) and a reversible capacity of similar to 639 mAh g(-1) at 1 A g(-1) up to the 1800th cycle, indicating that this Janus composite can be a promising anode for Li-ion batteries.