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

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 SnSex 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 SnSex 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.