Heterostructures of MoO3 nanobelts assembled on delaminated V4C3Tx MXene nanosheets for supercapacitors with excellent room/high temperature performance

A novel flexible delaminated vanadium carbide MXene (d-V4C3Tx) and molybdenum trioxide (MoO3) are promising electrode materials. However, the re-stacking of the d-V4C3Tx nanosheets and the poor conductivity and cyclic stability of MoO3 seriously restrict their development for supercapacitors application. Constructing heterostructures to obtain a synergistic property enhancement is an effective strategy to solve it. Herein, the free-standing d-V4C3Tx/MoO3 heterostructure composite films are fabricated by combining hydrothermal, electro-static assembly with vacuum-assisted filtration methods, and the energy storage mechanism is dominated by diffusion-controlled process. Results indicate that the as-prepared composite film electrode has high specific capacity of 645 0 C g- 1 at current density of 1 A g- 1. Even at 40 degrees C, it also has 639.2 C g- 1 at a scan rate of 2 mV s- 1. This impressive electrochemical performance can be attributed to the enhanced conductivity and high pseudocapacitance offered by the heterostructures. The as-fabricated asymmetric supercapacitor (ASC), in which the d-V4C3Tx/MoO3 composite film is used as negative electrode and the active carbon (AC) is used as positive electrode, exhibits maximum energy density of 22.2 Wh kg- 1 and maximum power density of 5289.9 W kg- 1, and the capacity retention rate can still up to 97.0% even after 10,000 cycles at a current density of 10 A g- 1. Furthermore, the assembled ASC device successfully drives the small alarm clock and lights the light emitting diode (LED), which facilitates the development of applications for such high-performance supercapacitors.

Automated summary

A flexible delaminated vanadium carbide MXene and molybdenum trioxide heterostructure composite film with high specific capacity and excellent electrochemical performance is fabricated. It shows great potential for supercapacitor applications.