## 3 EMA and Flame-Retardant Dual-Functional MOF Composites
### Polymetallic MOF
Figure 8: CoC@FeNiG-F: (**a**) schematic diagram of synthesis process, (**b**) 3D RL diagram, (**c**) vertical combustion test, (**d**) HRR, (**e**) THR, (**f**) SPR, and (**g**) COP ([94] free © 2023 Wiley). Figure 9: CCNT-FeCoNi/C: (**a**) schematic diagram of synthesis process and SEM diagram, (**b**) 3D RL diagram, (**c**) 2D RL plane map, (**d**) RL–f curve, (**e**) thermal infrared image at 100 \({}^{\circ}\)C, and (**f**) alcohol lamp combustion test (reprinted with permission from [95] © 2024 Elsevier). [PERSON] et al. [97] used a renewable wood-based porous carbon (WPC) scaffold as a template and its highly ordered internal cells as micro-reactors to fabricate an ultralight, flame-retardant, heat-insulating, and cyclically stable CoFe-MOF@Ti\({}_{3}\)C\({}_{2}\)T\({}_{\rm x}\) MXene@sodium alginate@WPC (MMSW) composite material (Figure 11a). As shown in Figure 11b,c, MMSW achieved a RL\({}_{\rm min}\) of \(-58.2\) dB and an EAB of \(5.8\) GHz (d = \(2.0\) mm). By varying the thickness of MMSW from \(1.5\) to \(6.0\) mm, the peak RL exceeded \(-20\) dB in the \(6\)-\(18\) GHz range. Compared to tissue paper, MMSW maintained its shape after being heated by an alcohol lamp for \(90\) s, demonstrating excellent flame retardancy (Figure 11f,g). Moreover, as shown in Figure 11d,e, a tissue paper placed on MMSW remained intact after \(90\) s, indicating that MMSW possesses excellent thermal stability and heat insulation properties. Additionally, MMSW displayed excellent Joule heating performance, showing high electric-thermal conversion efficiency after continuous voltage application. Molybdenum carbide (MoC) integrated into carbon matrices is renowned for its strong interfacial polarization functionality, making it a promising ultra-light microwave absorber. As shown in Figure 12a, [PERSON] et al. [98] synthesized ZnMo-HZIF foam materials using a solvent-free ball milling method by controlling the milling time. The multifunctional MoC-incorporated carbon matrix (MoC-C) was then synthesized by impregnation deposition thermal reduction from MF and ZnMo-HZIF. The target sample exhibited excellent EMA performance. At a \(15\) wt.% loading and \(2.5\) mm thickness, it achieved a RL\({}_{\rm min}\) of \(-47.56\) dB and an EAB of \(4.4\) GHz, covering almost the entire X-band (Figure 12b,c). To evaluate the sample's EMA capability in practical scenarios, CST simulation software was used to model the RCS of a PEC plate coated with a uniform absorber. As shown in Figure 12d,e, the RCS  
Figure 10: CNT-rGO-Co/Ni-MOF: **(a)** schematic diagram of synthesis process and SEM diagram, **(b)** 3D RL diagram, **(c)** 2D RL plane map, **(d)** RL–f curve, **(e)** alcohol lamp combustion test, and **(f)** HRR (reprinted with permission from [96] © 2024 American Chemical Society). value of the MoC-C remained below \(-10\) dB\(\cdot\)m\({}^{2}\) across the entire detection angle range, demonstrating the superior EMA capability compared to other samples. In Figure 12f, MoC-C and pure MF were exposed to an alcohol lamp flame for 20 s. Pure MF quickly shrank, and its structural integrity was severely compromised, while MoC-C showed minimal shrinkage and carbonization, maintaining its original shape. This indicates that the incorporation of ZnMo-HZIF significantly enhanced the flame retardancy of the MF-based material. To test the thermal insulation stability of MoC-C, its infrared thermal imaging temperature was compared with several commercial insulating materials, including NF, high-density polyurethane foam (HPU), and polystyrene foam (PS). After exposure to a heating platform set at 150 \({}^{\circ}\)C and 200 \({}^{\circ}\)C for 10 min, as shown in Figure 12h, MoC-C maintained a lower temperature than NF, HPU, and PS throughout the heating process, demonstrating its excellent thermal insulation performance. Figure 12g shows that when an infrared camera captured the heated aircraft model, MoC-C displayed outstanding stealth capability under infrared radiation.