Microwave-assisted ionothermal synthesis of SnSex nanodots: a facile precursor approach towards SnSe2 nanodots/graphene nanocomposites

Abstract

Presented here is a facile approach towards spherical SnSe₂ nanodots/graphene nanocomposites via an ionic liquid media assembly process, which involved an easily scaled-up microwave-assisted ionothermal synthesis of SnSe_x nanodots (NDs) as precursors by the reaction of elementary tin and selenium in (Bmmim)Cl (Bmmim = 1-butyl-2,3-dimethyl imidazolium) followed by an assembly process under ambient conditions and subsequent thermal treatment. The regulation of the content of SnSe₂ NDs could be conveniently achieved by varying the ratio of ND precursor to graphene oxide (GO). As evidenced by TG-MS and FTIR analysis, the assembly process could be attributed to the electrostatic interaction between the anionic GO and the positively charged SnSe_x NDs, which are fixed in the IL cation layer around the NDs as a medium. This conclusion was further confirmed by the TEM micrographs, which showed a constant particle size in the precursor and in the nanocomposites after thermal treatment. Lithium storage characterizations showed that the capacity of the as-prepared nanocomposite remained at 659 mA h g⁻¹ after 30 cycles at a current density of 150 mA g⁻¹, which is 1.5-times better than the theoretical capacity of SnSe₂ (426 mA h g⁻¹) and superior to the capacities of the previously reported SnSe₂ nanoplate/graphene composite and many other tin selenide electrodes. Thus, the new approach represents a promising, simple, and scalable synthetic protocol for the fabrication of lamellar metal dichalcogenide (LMD) NDs/graphene nanocomposites.