Mild synthesis of flower-like CuS modified MXene nanocomposites for high-performance supercapacitors and efficient microwave absorption

Abstract

Benefiting from rich surface functional groups, two-dimensional transition metal carbides (MXene) exhibit excellent metallic conductivity, hydrophilicity and film-forming properties and are widely used in energy storage and microwave absorption. However, the agglomerate and stacking of MXene nanosheets during preparation are largely detrimental to the full realization of their merits at two-dimensional scale. Therefore, we developed an ultrasonic assisted and vacuum filtration method to obtain MXene/CuS thin film electrode material with a "sandwich" structure without destroying its inherent properties, which still maintains a good lamellar structure and exhibits excellent tensile properties. Due to the synergistic effect of MXene and CuS and their redox reaction, the MXene/CuS thin film electrode exhibits a specific capacitance of 491 F g−1 at a current density of 1 A g−1. It can be used directly as positive and negative electrodes to assemble a flexible supercapacitor with a capacitance retention of 89 % at current density of 2 A g−1 after 5000 cycles. In addition, the composite can achieve an effective absorption band width of 3.3 GHz (14.7–18 GHZ) at a thickness of 1 mm. The study shows that layer spacing modulation offers the possibility of large-scale applications of MXene in the field of flexible supercapacitors and microwave absorption, and provides new ideas for the development of multi-purpose materials to meet the needs of different applications.