Electrospinning Machine | Point-Line-Plane" Three-Dimensional Synergistic Engineering in MoS2/CoFe2O4-Decorated Flexible Carbon Nanofiber Scaffold: A Dual-Functional Film for Integrated Microwave Absorption and Thermal Conductivity

The rapid advancement of modern electronics and communication systems has led to an increasingly complex electromagnetic environment. Electromagnetic interference and radiation have become significant challenges affecting both device performance and human health. Concurrently, with the ongoing progress in miniaturization and high-density integration technologies for electronic devices, the demand for effective thermal management is becoming increasingly critical. Therefore, developing microwave-absorbing/thermally conductive dual-functional materials that combine lightweight properties, broad frequency bands, and strong absorption characteristics has become an urgent priority.

Recently, Professor Huang Ying's research team at Northwestern Polytechnical University published their latest research findings in the journal Carbon, titled "Point-Line-Plane" Three-Dimensional Synergistic Engineering in MoS2/CoFe2O4-Decorated Flexible Carbon Nanofiber Scaffold: A Dual-Functional Film for Integrated Microwave Absorption and Thermal Conductivity". The first author of the paper is graduate student Jiang Huiyang, and the corresponding authors are Professor Huang Ying and Associate Researcher Zong Meng. The researchers utilized polyacrylonitrile-derived carbon nanofibers (CNF) as a flexible scaffold, synergistically integrating magnetic CoFe2O4 nanoparticles and dielectric MoS2 nanosheets. Through electrospinning combined with a pressure-assisted thermal molding process, precise control of the CNF-(MoS2/CoFe2O4) (CMC) heterointerface was achieved, ultimately obtaining a dual-functional flexible film material with excellent wave-absorbing and thermal conductive properties.

Experimental results demonstrated that the optimized CMC-1.0 sample achieved a minimum reflection loss (RLmin) of -45.6 dB in the 14.2 GHz frequency band, with a matching thickness of 3.0 mm. The sample also exhibited an effective absorption bandwidth (EAB) of 7.8 GHz (covering the 10.2 to 18 GHz frequency range) and a thermal conductivity of 0.163 W/(m·K). Furthermore, the resulting CMC film material displayed excellent flexibility. The CMC flexible wave-absorbing/thermal conductive dual-functional film material shows broad application prospects in electromagnetic wave absorption and thermal management for small electronic devices.

Fig. 1: CMC preparation flowchart.

The microstructure of CMC and CNF-MoS₂ films (CM) was systematically characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). As shown in Fig. 2a, cellulose nanofibrils (CNF) loaded with CoFe₂O₄ nanoparticles formed a tightly interconnected three-dimensional network within the CMC system, exhibiting uniform fiber diameter distribution. High-magnification SEM images (Fig. 2b–c) revealed that CoFe₂O₄ nanoparticles with an average size of 500 nm were uniformly embedded in the high-aspect-ratio CNF matrix (approximately 100 nm in diameter), forming a unique spindle-like composite structure. Fig. 2d displays the interfacial morphology between the CNF-CoFe₂O₄ (CC) film and the CM film on the CMC surface, where the CC film is clearly layered on top of the CM film. It is noteworthy that the CNFs constituting CM and those in CC exhibit significant morphological differences, with the slender fibrous structures in CM showing a more uniform diameter distribution. Cross-sectional SEM imaging coupled with energy-dispersive spectroscopy (EDS) (Fig. 2e1–e6) clearly revealed the sandwich structure of the CMC film: a central CM layer flanked on both sides by CC layers, with the elemental distribution patterns fully consistent with the expected composition.

Fig. 2: (a-c) SEM images of the CMC surface at different resolutions; (d) SEM micrograph of the interface between the CC layer and CM layer on the CMC surface; (e1-e6) Cross-sectional SEM images of the CMC film and corresponding EDS element distribution maps; (f-g) SEM images of the CM surface at different magnifications; (h) TEM image of carbon fibers in CM; (i) SAED diffraction pattern of the CM sample; (j) HR-TEM image of the CM sample; (k1-k4) EDS element distribution maps of CM carbon fibers.

As shown in Fig. 3, the absorption characteristics exhibit significant variations with increasing MoS₂ content (CMC-0.5, CMC-1.0, CMC-1.5). Under a thickness of 3.5 mm, CMC-0.5 achieves a minimum reflection loss (RLmin) of -19 dB, and its effective absorption bandwidth (EAB) expands to 5.4 GHz at a thickness of 4.0 mm. When loaded with 1.0 g of molybdenum disulfide, CMC-1.0 demonstrates exceptional broadband absorption performance, achieving an RLmin of -45.6 dB at a thickness of 3.0 mm, with an EAB reaching 7.8 GHz. CMC-1.5 attains an RLmin of -38 dB at a thickness of 1.7 mm, and its EAB extends to 8.0 GHz at a thickness of 2.7 mm, fully demonstrating its excellent thickness tunability.

 Fig. 3: (a1)-(a3) Reflection loss curves and 3D schematic of CMC-0.5; (b1)-(b3) Reflection loss curves and 3D schematic of CMC-1.0; (c1)-(c3) Reflection loss characteristics and 3D schematic of CMC-1.5.

To develop lightweight flexible film materials integrating excellent microwave absorption and thermal conductivity properties, we systematically evaluated the thermal conduction characteristics of CC, CMC-0.5, CMC-1.0, and CMC-1.5. As shown in Fig. 4, the CC film exhibits an extremely low thermal conductivity of only 0.00049 W/(m·K), demonstrating superior thermal insulation performance. In contrast, the CMC series shows significantly enhanced thermal conductivity, with values ranging from 0.147 to 0.163 W/(m·K).

Fig. 4: Comparison of thermal conductivity coefficients of CC, CMC-0.5, CMC-1.0, and CMC-1.5.

Fig. 5: Schematic diagrams of CMC (a) bending, (b) shaping, and (c) recovery.

In summary, the prepared CMC dual-functional flexible film material demonstrates favorable mechanical properties and excellent flexibility. Its outstanding microwave absorption and thermal conductivity performance make the CMC dual-functional film a promising candidate for high-performance electromagnetic wave absorption and thermal management materials in next-generation flexible electronic devices.

 Paper link: https://www.sciencedirect.com/science/article/pii/S0008622325007250