Fabrication of van der Waals Heterostructured FePSe3/Carbon Hybrid Nanosheets for Sodium Storage with High Performance

Iron phosphorus triselenide (FePSe3) is attractive for energy applications owing to its interesting layered geometry, electronic structure, and physiochemical property, while it is limited in actual application because of a very long fabrication time of over 7 days. Herein, we report a new synthetic route to a high-quality sheetlike hybrid of iron phosphorus triselenide nanocrystals coated with graphitic carbon (FePSe3/C) as an alternative kind of van der Waals heterostructures for the first time via a pyrolytic process at 600 °C from the precursors of ferrocene, red phosphorus, and selenium in a quartz tube with a significantly shortened reaction time of 24 h and even down to 30 min. Investigations demonstrated that the component phase of FePSe3 in the layered FePSe3/C hybrid nanosheets is the rhombohedral phase, and the hybrid nanosheets other than bulk crystals are about 15 nm in thickness. Acting as a cathode in fabricating half-cell sodium-ion batteries, the layered FePSe3/C hybrid nanosheets exhibited remarkable performance. Typically, when current density was set as 50 mA g–1, the hybrid nanosheet-assembled battery exhibited a capacity of 182.7 mA h g–1 after performing over 50 cycles, and the nanosheet battery exhibited a capacity of 142 mA h g–1 after performing for 200 cycling trials at 1 A g–1 in the 0.8–2.2 V voltage window. Meanwhile, the layered FePSe3/C hybrid nanosheets also exhibited very high rate capabilities at a relatively large current density in the present study, that is, 172 and 95 mA h g–1 under typical performing conditions at 0.5 and 5 A g–1, respectively.