Generation of Monolayer MoS2 with 1T Phase by Spatial-Confinement-Induced Ultrathin PPy Anchoring for High-Performance Supercapacitor

Integrating with conducting polymer (CP) is one of the effective ways to enhance the capacitive properties for MoS2 except for the controllable preparation of ultrathin MoS2 nanosheets or appropriate phase. However, most of the MoS2/CP composites are synthesized by traditional chemical method, in which way the structural optimization of MoS2 is limited. Here, a facile electrochemical method is demonstrated to optimize MoS2 by spatial-confinement-induced polypyrrole (PPy) anchoring. Compared with MoS2/PPy (MP) nanocomposites synthesized by chemical method, the electrochemical prepared possesses a concomitant MoS2 monolayer, together with a transition from semiconductor phase (2H-MoS2) to metallic phase (1T-MoS2) during the PPy coating. Consequently, the resultant MP nanocomposite shows a remarkable capacitive performance with a high capacitance of 613 F g(-1) at a current density of 1 A g(-1). Meanwhile, it possesses a good rate capability that the specific capacitance retains 74%, as the current density is increased to 10 A g(-1). The outstanding capacitive performance should be attributed to the existence of 1T-MoS2 monolayer and ultrathin PPy layer as well as their effective contacts.