ABSTRACT
Due to bimetallic MOFs (metal-organic frameworks) possessing diverse structure topologies and superior properties, herein, we used bimetallic ZIFs (zeolitic imidazole frameworks) of MOFs as precursors via the wet chemical and calcination method to fabricate zinc-embellished Co-Zn@NPC@MWCNT nanocomposites with porous conductive carbon-based networks The abundant carbon defects, zinc evaporation, and N-atom doping resulted in the emergence of dipolar/interface polarization, which is good for dielectric loss. The high porosity and large specific surface area were instrumental in the attenuation of multiple scattering and endowed the absorber with an excellent absorption performance. With merely 15 wt% filled loading and 3.187 mm thickness, the obtained composites under the optimized carbonization temperature (800 °C) exhibited double absorption peaks: the RLmin (minimum reflection loss) reached -76.18 dB@12.88 GHz and -33.09 dB@7.76 GHz, respectively. Moreover, a wide absorption bandwidth can be up to 6.56 GHz (7.2-13.76 GHz) with 3.0 mm thickness, distributed in three frequency bands: 20% of the C band, 100% of the X band, and 29.3% of the Ku band. In addition, the conductive network structure of composites was also beneficial for electromagnetic (EM)-wave absorption. An easy preparation process and low cost can further promote the commercial potential of our obtained bimetallic MOF-based material as an EM-wave absorber.
ABSTRACT
A facile resilient bismuthine-anchored graphene architecture is reported as multifunctional all-solid-state flexible supercapacitors and ionic-type capacitive sensor. Meanwhile, an electrons/ions dual transport channels design is achieved by inserting elaborately conductive bismuthene flakes into hierarchical porous aerogel framework. This strategy concurrently realizes the expansion of interlayer space for favoring electrolyte infiltration, and boost of interlayer conductivity to ensure interlayer electrons transport, endowing the device with attractive electrochemical energy storage and pressure sensing performance. As a result, the fabricated flexible symmetric supercapacitor device using bismuthene-graphene architecture as both negative and positive electrode delivers an excellent energy density of 45.55 Wh/kg at 400 W/kg along with cycling stability of 89.24% even after 3600 charge/discharge cycles. The bismuthene-graphene aerogel-based capacitive sensor with the hierarchical porous architecture demonstrates a high sensitivity of 0.326 kPa-1. Furthermore, the sensing mechanisms of ionic-type pressure sensor is explored. This work clearly demonstrates that the novel 3D hierarchical bismuthene-graphene architecture can be widely used in multifunctional devices of supercapacitors and tactile sensors.
