Facile fabrication of novel Ti₃C₂T_x-supported fallen leaf-like Bi₂S₃ nanopieces by a combined local-repulsion and macroscopic attraction strategy with enhanced symmetrical supercapacitor performance

Hybrid electrode materials with superior electrochemical performance are highly desired to fulfil the ever-increasing energy-density demands of supercapacitors. Herein, a facile and efficient ion-attraction strategy is demonstrated for the construction of a uniform heterostructure of Bi₂S₃/Ti₃C₂T_x (BSTC) nanocomposites, in which fallen leaf-like Bi₂S₃ nanopieces are firstly planted on the surface of Ti₃C₂T_x due to the local-repulsion of Ti atoms and the macroscopic attraction of functional groups (OH/O/F) to Bi³⁺. The DFT calculation was conducted to explain the morphology transformation mechanism from nanoparticles to nanopieces and the enhancement of the electrical conductivity of Bi₂S₃ is due to the incorporation of Ti₃C₂T_x. When used as a supercapacitor electrode, the BSTC-29 (Ti₃C₂T_x content: 29 wt.%) nanocomposite exhibits a superior electrochemical performance with an enhanced capacity of 615 C g^-1 at a high discharge current density of 3 A g^-1, and a high capacitance retention up to 91% is also obtained due to the enhanced structural stability. Furthermore, the assembled symmetrical supercapacitor exhibits both a high energy density of 27.6 Wh kg^-1 and a power density of 24.3 kW kg^-1, respectively, surpassing those of Bi₂S₃ and Ti₃C₂T_x in this study and many other related composites in literature. This study presents a new promising strategy for the synthesis of high-performance supercapacitor electrode materials.