A Comparative Electrochemical Study of 2H/1T Phases of MoS2 and Designing 1T- MoS2@Cu2S for High-Performance Supercapacitor

Abstract

Two-dimensional materials, such as MoS2, have recently attracted significant attention for their excellent electrical properties, offering great potential for sustainable energy storage solutions through supercapacitor applications. In this study, we conduct a comparative investigation of the supercapacitor performance of two phases of MoS2, namely the semiconducting 2H phase and the metallic 1T phase. Additionally, we employed two distinct and complementary synthesis approaches, namely exfoliation and hydrothermal synthesis, to determine the most effective strategy for enhancing supercapacitor performance. Our results show that the 1T phase synthesized via the hydrothermal method exhibits superior supercapacitor performance. Nevertheless, the intrinsic limitations of MoS2, including its low density of active edge sites and inert basal plane, hinder its electrochemical activity. To address these challenges, Cu2S was strategically incorporated into the 1T phase of MoS2, forming a hierarchical composite with snowflake-like morphology and dendritic structure. This architecture promotes efficient ion transport and ensures a seamless electrode–electrolyte interface. Moreover, the composite facilitates a synergistic charge transfer network between MoS2 and Cu2S by leveraging the metallic nature of the 1T phase, achieving a high specific capacitance of 1118 F g−1 at 1 A g−1. When paired with MnO2 in an asymmetric hybrid device, it delivers an impressive energy density of 141 Wh kg−1 and a power density of 19,000 W kg−1, highlighting its promise for next-generation energy storage systems.