Design and fabrication of self-supporting, ultra-flexible, multi-heterogeneous CNT@MOF buckypaper with microwave absorption and energy storage properties

The rapidly growing demand for wearable electronics with anti-electromagnetic interference, self-powering capabilities, and ultra-flexible has created a pressing need for advanced materials that can address these challenges simultaneously. Current material systems face inherent contradictions: while microwave-absorbing materials require controlled conductivity to prevent impedance mismatch, electrode materials necessitate high conductivity for efficient charge transport. To resolve this dichotomy, a self-supporting, ultra-flexible CNT@NiCo-MOF buckypaper (CNT@NCM BP) was fabricated without the need for additional adhesive, employing a solvothermal method combined with the directional pressure filtration technique. By virtue of the synergistic interaction between MOF and CNT, the BP exhibits remarkable microwave absorption and energy storage properties. The BP achieved a minimum reflection loss of −58.3 dB and an ultra-wide effective absorption bandwidth of 7.0 GHz, particularly in the 2–8 GHz low-frequency range. Moreover, the BP electrode exhibited a specific capacitance of 16.91 F·cm⁻² when operated at 3 mA·cm⁻² current density. The ultra-flexible all-solid symmetric supercapacitor (ASSC) achieved an impressive energy density of 1.10 mWh·cm⁻² paired with a power density of 10.5 mW·cm⁻². Moreover, ASSC exhibits extremely high cyclic stability (108.8 % after 10000 cycles) at 50 mA·cm⁻². And, the BP demonstrates ultra-flexibility by maintaining structural integrity under various mechanical deformations. This study aims to construct a multifunctional self-supporting material that integrates electromagnetic protection with a self-powered energy system into flexible electronic products.