## 3 EMA and Flame-Retardant Dual-Functional MOF Composites
### Polymetallic MOF  
Polymetallic MOFs have received a lot of attention as new functional materials because of their adjustable structures and diverse functions. Composite materials designed based on polymetallic MOFs exhibit excellent EMA, flame retardancy, thermal insulation, and mechanical properties, making them a hot research topic in the development of novel high-performance materials [50; 91; 92; 93]. As shown in Figure 8a, [PERSON] et al. [94] developed a multifunctional CoC@FeNiG-F nanocomposite using an in situ growth and multiphase synergy strategy by combining ZIF-67 and FeNi-MOF. The CoC@FeNiG-F nanocomposite demonstrated exceptional EMA performance, achieving a RLmin of \(-\)75.19 dB with an EAB of 3.95 GHz at a thickness of 2.4 mm (Figure 8b). The combustion behavior of CoC@FeNiG-F-incorporated EP was investigated through LOI and UL-94 vertical burning tests. As shown in Figure 8c, the CoC@FeNiG-F composite achieved a LOI of 31.2% and a UL-94 V-0 rating. CCT further revealed significant reductions in pHRR, THR, pSPR, and pCOP by 68.77%, 36.53%, 48.39%, and 56.14%, respectively, compared to pure EP (Figure 8d-g). Additionally, the composite material exhibited outstanding mechanical properties (80.3 MPa), superamphiphobicity (contact angles of 153\({}^{\circ}\) and 151\({}^{\circ}\) for water and oil, respectively), long-term corrosion resistance (45 d), and mechanical durability, highlighting its potential for advanced multifunctional applications. The innovative synthesis methods for trimetallic MOFs have opened new pathways for the study of composite materials. [PERSON] et al. [95] employed a liquid nitrogen directional freezing strategy to load spindle-shaped trimetallic MOFs onto the pore walls of aerogels. After carbonization, they obtained a 3D carbon aerogel composite derived from trimetallic MOFs, named CCNT-FeCoNi/C (Figure 9a). As illustrated in Figure 9b-d, the CCNT-FeCoNi/C composite exhibited remarkable EMA performance. At a loading of 5 wt.%, the composite achieved a RLmin of \(-\)61.55 dB (d = 2.42 mm) and a maximum EAB of 7.2 GHz (d = 2.82 mm). To assess its flame retardancy, a burning test was conducted using  
Figure 7: Ti\({}_{3}\)CNT\({}_{x}\)/Ni@C: (**a**) schematic diagram of the synthesis process, (**b**) alcohol lamp combustion test, (**c**) thermal infrared image at 62.0 \({}^{\circ}\)C, (**d**) 3D RL diagram, (**e**) 2D impedance matching plane map, and (**f**) RL–f curve (reprinted with permission from [90] © 2022 Elsevier). an alcohol lamp. As shown in Figure 9f, the shape of the composite aerogel remained nearly unchanged during the 30 s burning test, demonstrating the excellent flame-retardant properties of CCNT-FeCoNi/C. Furthermore, as shown in Figure 9e, the composite aerogel exhibited thermal insulation properties when placed on a hot platform at 100 \({}^{\circ}\)C, further highlighting its multifunctional potential for advanced applications. Using a multidimensional design strategy, [PERSON] et al. [96] successfully developed a novel EMA material by combining carboxylated CNTs with graphene oxide (GO) and loading Co/Ni-MOF onto the surface of GO using its rich functional groups. This resulted in the EMA composite CNT-rGO-Co/Ni-MOF (Figure 10a). As shown in Figure 10b-d, CNT-rGO-Co/Ni-MOF exhibited remarkable EMA properties, achieving a significant RL\({}_{\text{min}}\) of \(-43.0\) dB and an EAB greater than 4.0 GHz at 25 wt.% loading (d = 1.5 mm). When 10 wt.% of CNT-rGO-Co/Ni-MOF was added to EP, the composite material did not ignite within 60 s, in stark contrast to pure EP, which rapidly ignited (Figure 10e). Additionally, as shown in Figure 10f, compared to pure EP, the HRC, pHRR, and THR of EP/CNT-rGO-Co/Ni-MOF were reduced by 59.2%, 52.6%, and 20.8%, respectively, demonstrating excellent flame retardancy. In the research of high-performance composites, using renewable resources as scaffold templates to fabricate novel composites has become a green and efficient strategy.