In situ construction of a dual-metal 2D conjugated metal-organic framework on carbon paper for asymmetric supercapacitors

Two-dimensional conjugated metal-organic frameworks (2D c -MOFs), with their excellent electrical conductivity, high porosity, large specific surface area, and tunable active sites, have emerged as promising electrode materials for supercapacitors. However, limited charge transport pathways and low electron mobility in single-metal 2D c -MOFs significantly restrict their energy storage performance. To overcome these limitations, we propose a universal and innovative strategy for constructing bimetallic 2D c -MOFs. Activated carbon paper (CP) was used as the substrate. By adjusting the ratios of different metal ions (M 1 /M 2 = Co, Cu, Ni), a bottom-up in situ self-assembly strategy was employed to synthesize three types of M 1 /M 2 -HHTP@CP electrode materials (Co/Ni-HHTP@CP, Co/Cu-HHTP@CP, Cu/Ni-HHTP@CP; HHTP = 2,3,6,7,10,11-hexahydroxytriphenylene). The results show that the synergistic effect of Co and Ni is stronger than that of Co/Cu or Cu/Ni. Furthermore, the strengthened chemical bonding between Co/Ni-HHTP and CP markedly enhances the stability and electron transport of the electrode, resulting in a high specific capacitance of 544 F g −1 for Co/Ni-HHTP@CP. When assembled into an asymmetric supercapacitor (Co/Ni-HHTP@CP || AC), the device delivers a power density of 400 W kg −1 and an energy density of 52.11 W h kg −1 , while maintaining 93.02 % of its initial capacitance and 95.96 % Coulombic efficiency even after 5000 cycles. This study offers a new strategy for the rational design of bimetallic 2D c -MOFs-based supercapacitors. • A simplified method for the oxidation treatment of carbon paper has been developed. • The in-situ growth method facilitates the formation of a robust covalent bond between the c -MOFs and the carbon paper surface, bestowing the composite material with exceptional cycling stability. • The synergistic interactions between the two metals significantly enhance the material's redox activity and charge storage efficiency. • The current density of the Co/Ni-HHTP@CP electrode material is 1.0 A g −1 , and the specific capacitance reaches 544 F g -1. • The asymmetric supercapacitor Co/Ni-HHTP@CP||AC maintains a capacity retention rate of 93.02 % after 5000 charge-discharge cycles.