High-temperature carbonized metal-organic frameworks (MOFs) derivatives have demonstrated their superiority for promising electromagnetic wave (EMW) absorbers, but they still suffer from limited EMW absorption capacity and narrow bandwidth. Considering the advantage of microstructure and chemical composition regulation for the design of EMW absorber, hierarchical heterostructured MoS₂/CoS₂-Co₃O₄@cabonized cotton fabric (CF) (MCC@CCF) is prepared by growing ZIF-67 MOFs onto CF surface, chemical etching, and carbonization. Aside from the dual loss mechanism of magnetic-dielectric multicomponent carbonized MOFs, chemical etching and carbonization process can effectively introduce abundant micro-gap structure that can result in better impedance matching and stronger absorption capacity via internal reflection, doped heteroatoms (Mo, N, S) to supply additional dipolar polarization loss, and numerous heterointerfaces among MoS₂, CoS₂, Co₃O₄, and CCF that produce promoted conduction loss and interfacial polarization loss. Thus, a minimal reflection loss of −52.87 dB and a broadest effective absorption bandwidth of 6.88 GHz were achieved via tunning the sample thickness and filler loading, showing excellent EMW absorption performances. This research is of great value for guiding the research on MOFs derivatives based EMW absorbing materials.

Rational construction of hierarchical multi-component materials with abundant heterostructure is evolving as a promising strategy to achieve excellent metal-organic frameworks (MOFs) based electromagnetic wave (EMW) absorbers. Herein, hierarchical heterostructure WS₂/CoS₂@carbonized cotton fiber (CCF) was fabricated using the ZIF-67 MOFs nanosheets anchored cotton fiber (ZIF-67@CF) as a precursor through the tungsten etching, sulfurization, and carbonization process. Apart from the synergetic effect of dielectric-magnetic dual-loss mechanism, the hierarchical heterostructure and multicomponent of WS₂/CoS₂@CCF also display improved impedance matching. Furthermore, numerous W-S-Co bands and heterojunction interfaces of heterogeneous WS₂/CoS₂ are beneficial to promoting additional interfacial/dipole polarization loss and conductive loss, thereby enhancing the EMW attenuation performance. Based on the percolation theory, a good balance between impedance matching and EMW absorption capacity was achieved for the WS₂/CoS₂@CCF/paraffin composite with 20 wt.% filler loading, exhibiting strong EMW absorption capability with a minimum reflection loss (RL_min) value of −51.26 dB at 17.36 GHz with 2 mm thickness and a maximum effective absorption bandwidth (EAB_max) as wide as 6.72 GHz. Our research will provide new guidance for designing high-efficient MOFs derived EMW absorbers.

Flexible pressure sensors have attracted wide attention due to their applications to electronic skin, health monitoring, and human-machine interaction. However, the tradeoff between their high sensitivity and wide response range remains a challenge. Inspired by human skin, we select commercial silicon carbide sandpaper as a template to fabricate carbon nanotube (CNT)/polydimethylsiloxane (PDMS) composite film with a hierarchical structured surface (h-CNT/PDMS) through solution blending and blade coating and then assemble the h-CNT/PDMS composite film with interdigitated electrodes and polyurethane (PU) scotch tape to obtain an h-CNT/PDMS-based flexible pressure sensor. Based on in-situ optical images and finite element analysis, the significant compressive contact effect between the hierarchical structured surface of h-CNT/PDMS and the interdigitated electrode leads to enhanced pressure sensitivity and a wider response range (0.1661 ​kPa⁻¹, 0.4574 ​kPa⁻¹ and 0.0989 ​kPa⁻¹ in the pressure range of 0–18 ​kPa, 18–133 ​kPa and 133–300 ​kPa) compared with planar CNT/PDMS composite film (0.0066 ​kPa⁻¹ in the pressure range of 0–240 ​kPa). The prepared pressure sensor displays rapid response/recovery time, excellent stability, durability, and stable response to different loading modes (bending and torsion). In addition, our pressure sensor can be utilized to accurately monitor and discriminate various stimuli ranging from human motions to pressure magnitude and spatial distribution. This study supplies important guidance for the fabrication of flexible pressure sensors with superior sensing performance in next-generation wearable electronic devices.