Conductive Bismuth-Catecholate Metal–Organic Frameworks Grown on Ti₃C₂T_x Nanosheets for High-Performance Supercapacitors

Ti 3 C 2 T 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, Ti 3 C 2 T 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 Ti 3 C 2 T x nanosheets (Ti 3 C 2 T x /Bi(HHTP)) for supercapacitors. In the hybrid structure, conductive Bi(HHTP) serves not only as the spacers to relieve the self-stacking of Ti 3 C 2 T x nanosheets but also as the active component to provide battery-type capacitance. Meanwhile, Ti 3 C 2 T x nanosheets provide skeletons for the conductive Bi(HHTP), further enhancing the overall specific capacitance of Ti 3 C 2 T x /Bi(HHTP). By taking advantage of appropriate porosity, redox activity, and good properties of charge transport of Bi(HHTP), the specific capacitance of Ti 3 C 2 T x nanosheets is significantly increased. The Ti 3 C 2 T 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 Ti 3 C 2 T 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 Ti 3 C 2 T x, offering potential avenues for enhancing performance in energy storage applications.