Ternary Composite Nanosheets with MoS₂/WS₂/Graphene Heterostructures as High‐Performance Cathode Materials for Supercapacitors

Abstract

Abstract A new class of ternary heterostructures consisting of a reduced graphene oxide, molybdenum disulfide, and tungsten disulfide (rGO‐MoS 2 ‐WS 2 ) is prepared through a simple chemical method. According to Raman and X‐ray photoelectron spectroscopy, a MoS 2 /WS 2 heterostructure is uniformly formed on the conductive rGO support. Furthermore, rGO‐MoS 2 ‐WS 2 possesses s large surface area of 109 m 2 g −1 and a hierarchical pore architecture. When serving as the electrode for supercapacitors, rGO‐MoS 2 ‐WS 2 exhibits pseudocapacitive behavior in a KOH solution. It is found that rGO‐MoS 2 ‐WS 2 displays a specific capacitance ( C s ) of 365 F g −1 at 1 A g −1 , which is much higher than those of single TMD (MoS 2 or WS 2 )‐based composites. The enhanced electrochemical performance of rGO‐MoS 2 ‐WS 2 is attributed to the lower internal resistance through heterostructure formation, the wide range of TMD oxidation states, and uniform distribution of the few‐layered TMD nanosheets on the rGO surface. Furthermore, the optimal loading amount of MoS 2 /WS 2 heterostructure in the composite is investigated. To demonstrate its practical application, rGO‐MoS 2 ‐WS 2 is used as a positive electrode for an asymmetric supercapacitor (ASC). The maximum energy density of the ASC device is 15 Wh kg −1 at a power density of 373 W kg −1 . Furthermore, the device remains approximately 70 % of the initial C s value after 3000 cycles, which shows the excellent cycling stability.