High-performance flexible conductive films are highly promising for the development of wearable devices, artificial intelligence, medical care, etc. Herein, a three-step procedure was developed to produce electromagnetic interference (EMI) shielding, Joule heating, and a hydrophobic nanofiber film based on hydrolysate of waste leather scraps (HWLS): (i) electrospinning preparation of the HWLS/polyacrylonitrile (PAN)/ zeolitic imidazolate framework-67 (ZIF-67) nanofiber film, (ii) carbonization of the HWLS/PAN/ZIF-67 nanofiber film, and (iii) coating of the carbon nanofiber@cobalt (Co@CNF) nanofiber film with perfluorooctyltriethoxysilane (POTS). The X-ray diffraction results showed that metal nanoparticles and amorphous carbon had obvious peaks. The micromorphology results showed that metal nanoparticles were coated with carbon nanofibers. The conductivity and shielding efficiency of the carbon nanofiber film with 250 μm thickness could reach 45 S/m and 49 dB, respectively, and absorption values (A > 0.5) were higher than reflection (R) values for the Co@CNF nanofiber film, which indicated that the contribution of absorption loss was more significant than that of reflection loss. Ultrafast electrothermal response performances were also achieved, which could guarantee the normal functioning of films in cold conditions. The water contact angle of the Co@CNF@POTS nanofiber film was ∼151.3°, which displayed a self-cleaning property with water-proofing and antifouling. Absorption-dominant and low-reflection EMI shielding and electrothermal films not only showed broad application potential in flexible wearable electronic devices but also provided new avenues for the utilization of leather solid waste.
Flexible sensors with multifunctions have attracted great attention for their extensive application values. Most of the reported multifunctional flexible sensors lack the intuitive signal display function, have limitations of work environment, and are weakly resistant to electromagnetic waves, and the landfill and incineration of the sensor wastes could pose irreversible damage to the environment. Herein, a trilayer composite (referred to as TGM) is prepared by the layer-by-layer assembly of MXene, gelatin, and a water-based multiporous membrane (WMM), which exhibits a hierarchically ordered bionic heterostructure. The top layer is multilayers of MXene nanosheets, the middle layer consists of artificial neural cages and synapses from an MXene@gelatin structure, and the bottom layer is a brick-mortar mimic of MXene@WMM. The resulting TGM heterostructure displays excellent performance in pressure sensing both in air and under water due to the ready variation of the electrical conductivity with applied pressures. The TGM composite also shows an apparent actuation response under IR, moisture, and heating stimulations. These multifunctional characteristics can be integrated for visual sensing of environmental temperature and humidity. Additionally, the composite possesses efficient electromagnetic shielding and shows great degradation. Results from this study highlight the unique potential of MXene−biomass composites in the development of eco-friendly multifunctional sensors.
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