Conductive Bismuth-Catecholate Metal–Organic Frameworks Grown on Ti3C2Tx Nanosheets for High-Performance Supercapacitors.

Ti₃C₂T_x, as a member of the two-dimensional (2D) MXene family, is subject to severe self-restacking due to van der Waals forces between the surfaces of the nanosheets, which limits its application in supercapacitors. In addition, Ti₃C₂T_x always stores electrical energy non-Faradaic, resulting in a low specific capacitance about 100 F g^–1 in basic electrolytes. In this work, we report conductive bismuth-catecholate metal–organic frameworks (Bi-(HHTP)) with one-dimensional (1D) channels grown on the surfaces of 2D Ti₃C₂T_x nanosheets (Ti₃C₂T_x/Bi-(HHTP)) for supercapacitors. In the hybrid structure, conductive Bi-(HHTP) serves not only as the spacers to relieve the self-stacking of Ti₃C₂T_x nanosheets but also as the active component to provide battery-type capacitance. Meanwhile, Ti₃C₂T_x nanosheets provide skeletons for the conductive Bi-(HHTP), further enhancing the overall specific capacitance of Ti₃C₂T_x/Bi-(HHTP). By taking advantage of appropriate porosity, redox activity, and good properties of charge transport of Bi-(HHTP), the specific capacitance of Ti₃C₂T_x nanosheets is significantly increased. The Ti₃C₂T_x/Bi-(HHTP) electrode obtained exhibits an impressive specific capacitance of 326 F g^–1 at 0.5 A g^–1 and a good rate capacity of 52%. Additionally, an asymmetric device is assembled with a Ni-(OH)₂ cathode and a Ti₃C₂T_x/Bi-(HHTP) anode, demonstrating remarkable performance with a maximum specific energy of 22.3 Wh kg^–1 and a maximum specific power of 11.2 kW kg^–1. This work presents a promising strategy for developing high-performance supercapacitor electrodes based on Ti₃C₂T_x, offering potential avenues for enhancing performance in energy storage applications. [ABSTRACT FROM AUTHOR]