Mixed-phase MoS2 decorated reduced graphene oxide hybrid composites for efficient symmetric supercapacitors

Abstract

In this work, we demonstrated the phase-tuned MoS2 layers (2H- MoS2, 1 T- MoS2, and 2H/1 T-MoS2) using a one-pot reaction, scientifically significant due to their impermeable characteristics. Strongly-bonded, vertically-aligned layers were perceived by transmission electron microscopy (TEM) for 2H/1 T-MoS2 layers. The spacing between the two layers was expanded to 0.67 nm, which is favorable for intercalation process. Further, mixed-phase MoS2 sheets were successively blended with reduced graphene oxide (rGO) to form 2H/1 T-MoS2@rGO hybrid. Spectroscopic studies verified the formation of phase-tuned MoS2 and 2H/1 T-MoS2@rGO hybrid. The resulting 2H/1 T-MoS2@rGO hybrid TEM micrograph shows the layered MoS2 lattices decorated rGO nano-structure. Symmetric supercapacitors constructed from 2H/1 T-MoS2@rGO hybrid electrodes demonstrated improved storage capacity with solid pseudo-capacitive behavior compared to the pure phases. Surface-modified 2H/1 T-MoS2@rGO nanostructures exhibited a high energy density of 55 Wh center dot kg(-1) at a power density of 3 kW center dot kg(-1) with a symmetric capacitance of 275 F center dot g(-1) at a current density of 1 A center dot g(-1), along with an excellent cyclic constancy (similar to 97% capacity after 5000 cycles).