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

Ti3C2Tx, 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, Ti3C2Tx 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 Ti3C2Tx nanosheets (Ti3C2Tx/Bi(HHTP)) for supercapacitors. In the hybrid structure, conductive Bi(HHTP) serves not only as the spacers to relieve the self-stacking of Ti3C2Tx nanosheets but also as the active component to provide battery-type capacitance. Meanwhile, Ti3C2Tx nanosheets provide skeletons for the conductive Bi(HHTP), further enhancing the overall specific capacitance of Ti3C2Tx/Bi(HHTP). By taking advantage of appropriate porosity, redox activity, and good properties of charge transport of Bi(HHTP), the specific capacitance of Ti3C2Tx nanosheets is significantly increased. The Ti3C2Tx/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 Ti3C2Tx/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 Ti3C2Tx, offering potential avenues for enhancing performance in energy storage applications.