Three-Dimensional Self-Supporting Ti3C2 with MoS2 and Cu2O Nanocrystals for High-Performance Flexible Supercapacitors.

The three-dimensional (3D) architecture of electrode materials with excellent stability and electrochemical activity is extremely desirable for high-performance supercapacitors. In this study, we develop a facile method for fabricating 3D self-supporting Ti3C2 with MoS2 and Cu2O nanocrystal composites for supercapacitor applications. MoS2 was incorporated in Ti3C2 using a hydrothermal method, and Cu2O was embedded in two-dimensional nanosheets by in situ chemical reduction. The resulting composite electrode showed a synergistic effect between the components. Ti3C2 served as a conductive additive to connect MoS2 nanosheets and facilitate charge transfer. MoS2 acted as an active spacer to increase the interlayer space of Ti3C2 and protect Ti3C2 from oxidation. Cu2O effectively prevented the collapse of the lamellar structure of Ti3C2-MoS2. Consequently, the optimized composite exhibited an excellent specific capacitance of 1459 F g-1 at a current density of 1 A g-1. Further, by assembling an all-solid-state flexible supercapacitor with activated carbon, a high energy density of 60.5 W h kg-1 was achieved at a power density of 103 W kg-1. Additionally, the supercapacitor exhibited a capacitance retention of 90% during 3000 charging-discharging cycles. Moreover, high mechanical robustness was retained after bending at different angles, thereby suggesting significant potential applications for future flexible and wearable devices.