It is of great significance to develop lightweight and efficient electromagnetic wave (EMW) absorption materials to counter the problems of electromagnetic interference, information security and national defense security. In recent years,nanoporous carbon composites derived from metal-organic frameworks (MOFs) have gained numerous attentions in the field of EMW absorption. Benefited from the highly adjustable pore structures and the tailored components and microstructures of MOFs, the in-situ generated metallic microwave absorption units in carbon matrix result in rich interfaces as well as compositions. Together with the cross-linked conductive network, the microwave loss mechanisms can be greatly enriched,leading to enhanced EMW absorption capability. The rational design of various components and the controllable construction of microstructures are the key to regulate the electromagnetic parameters. The rational design and performance regulation strategy of MOFs-derived carbon-based EMW absorbers in recent years are reviewed regarding incorporated metal types and spatial arrangement, heterogeneous structure of MOFs and porous structure of carbon matrix. Finally, the challenges and perspectives of MOFs-derived carbon composites in the application of EMW absorption are also presented.

With the popularization of high-frequency communication technology, the problem of electromagnetic radiation has received increasing attention. The construction of novel electromagnetic wave (EMW) absorption materials based on conductive metal-organic frameworks (MOFs) has become a research hotspot in recent years. In this work, MXene modified MOF/polypyrrole (PPy) was proposed, with which high-performance EMW absorption materials with broadband and strong absorption were successfully obtained through the cooperative optimization of dielectric loss of the three components. When the filling content is only 10 wt.%, the minimum reflection loss (RL_min) of the composites can reach -56.21 dB at a thin thickness of 1.98 mm, while the maximum effective absorption bandwidth (EAB) can be up to 7.12 GHz (10.88-18.00 GHz), which is superior to the conductive MOF-based microwave absorbers reported in the open literture. By analyzing the components and microstructure of the materials, it is found that the excess PPy is not only polymerized in-situ in the pores and outer surface of UiO-66, but also loaded on the MXene substrate, which effectively builds up conductive network and promotes the conductive loss. Meanwhile, the ternary heterogeneous interface composed of UiO-66, PPy and MXene greatly enhanced the interfacial polarization loss, which further promoted the attenuation of electromagnetic waves. In addition, the simple preparation process and high yield of MXene/UiO-66/PPy have strong potential for large-scale production, which is promising to be applied in the field of electromagnetic protection.

Powder metallurgy is important in material preparation. Due to the inertness of carbon materials, however, sintering powdered carbon into physically coherent bulks has been a great challenge even at a high temperature (2000 ℃). Improving the sintering activity of carbon powders is the key to the success of the consolidation of the carbon powders. Here ordered mesoporous carbon (OMC) is used as the starting material to produce highly homogeneous novel carbon bulks. During sintering at 1800 ℃, the huge specific surface area of the OMC greatly promotes the migration of carbon atoms and thus the sintering of the OMC by surface diffusion mechanism. When nanodiamond (ND) is added, the volume expansion associated with the phase transformation of diamond to graphite facilitates the densification of the powder compacts. The strong connection between the OMC and the graphite onions derived from the ND bestows the as-prepared carbon bulks with excellent mechanical properties. The current research pioneers a novel way to prepare high-strength carbon materials at relatively low temperatures.

As a semiconducting material with relatively low thermal conductivity, MoS₂ nanoflake has the potential to serve as a modulator for optimizing the performance of thermoelectric (TE) materials. However, the low yield of MoS₂ nanoflakes prepared by conventional methods has constrained the development of MoS₂ optimized TE materials. We propose a mechanical exfoliation method for mass production of MoS₂ nanoflakes using attrition mill. After mixed with La and Nb co-doped SrTiO₃ (SLNT) powder, the MoS₂/SLNT composites are fabricated by spark plasma sintering. It is found that the heterojunctions formed at MoS₂/SLNT interfaces with proper band offset can effectively scatter the low-energy electrons, resulting in enhanced Seebeck coefficient without significantly undermining the electrical conductivity. The power factor of composites is improved when the MoS₂ content is lower than 1.5 vol%. Meanwhile, the thermal conductivity of composites is significantly decreased due to the phonon scattering induced large thermal resistance at MoS₂/SLNT interfaces, which is much higher than that in graphene embedded SrTiO₃ composites. Consequently, a maximum ZT = 0.24 is obtained at 800 K in 1.5 vol% MoS₂/SLNT composite, which is ~26 % higher compared with pristine matrix. This work paves the way for application of TE materials modulated by transition metal dichalcogenides.