Enhanced pseudocapacitive performance of MoS2 by introduction of both N-GQDs and HCNT for flexible supercapacitors

In this work, we report a strategy for enhancing the pseudocapacitive performance of MoS₂ materials by the introduction of nitrogen-doped graphene quantum dots (N-GQDs) and helical carbon tubes (HCNT). By a simple hydrothermal process, the hybrid composite (MoS₂, N-GQDs and HCNT) were coated on the carbon cloth (CC) without any binders, which can be directly used as advanced electrode material for high-performance solid-state flexible supercapacitors. In this hybrid structure, N-GQDs are inserted between the layers of MoS₂ nanosheets, which induce and expose more active sites for pseudocapacitance contributions in MoS₂ electrode materials. Meanwhile, HCNT acts as electrically conducting bridge for enhancing the electrical conductivity of MoS₂ nanosheets and speeding up transport of electronic. As results, the hybrid composite (MoS₂, N-GQDs and HCNT) show higher capacitive performance than pure MoS₂. The specific capacitance of hybrid composite is high up to 3360 mF cm⁻². Further, the assembled solid-state flexible supercapacitor shows high specific capacitance of 1893 mF cm⁻², outstanding cycle life (capacitance retention of 86% after 2500 cycles), good mechanical stability and great flexibility. Our work provides a reference for the preparation of MoS₂ composites with high supercapacitive performance.