Metal/N-Doped Carbon Nanoparticles Derived from Metal–Organic Frameworks for Electromagnetic Wave Absorption

Abstract

Metal–organic frameworks (MOFs) have diverse structures and compositions, inspiring the boundless enthusiasm and creativity of researchers in the field of electromagnetism. The synthesis of MOF-derived nanomaterials for electromagnetic wave (EMW) absorption with ultrathin matching thickness (below 1.6 mm) is highly desired and challenging. Here, we demonstrate a general synthesis strategy for metal (Co, Ni, Fe)-based MOFs, which transformed into metal/metal-oxide nanoparticles (NPs) of being coated by nitrogen (N)-doped graphitized carbon. The obtained carbon-coated NPs show excellent EMW absorption properties. Specifically, Co-based MOFs are pyrolyzed into rhombic dodecahedrons with numerous ultrasmall Co NPs coated by N-doped carbon (Co-NC core–shell NPs). The synthesized Co-NC core–shell NPs possess a unique porous structure, abundant defects, and doped N heteroatoms, resulting in good magnetic loss (eddy current loss), dielectric loss (multiple reflections, interfacial polarization, conduction loss), and impedance matching. Therefore, the Co-NC core–shell NPs exhibit an excellent EMW absorption property with a very strong reflection loss of −56.5 dB at a matching thickness of only 1.58 mm. The effective absorption bandwidth (EAB) is 4.4 GHz. In addition, the EAB between 1 and 5 mm in thickness is up to 13.2 GHz, which already includes all C bands and X bands, even the absolute S bands and Ku bands. This work provides an avenue to design high-performance EMW absorption devices based on MOF-derived nanomaterials.

Interfacial engineering and chemical reconstruction of Mo/Mo2C@CoO@NC heterostructure for promoting oxygen evolution reaction

“…Furthermore, the peaks at 786.2 eV and 802.5 eV are shakeup satellites, which belong to Co 2+ . 34 These results further confirm the presence of CoO. At the same time, the C 1s peaks at 283.6 eV, 284.0 eV, 284.6 eV, and 287.4 eV can be attributed to Mo–C, C–C, C–N/C–O, and O–CO bonding (Fig.…”

“…The formation of the CoO phase originates from the carbonization of ZIF-67. 34 On the other hand, the MoO 3 @CoO x and MoO 3 @ZIF-67-P samples mainly show the MoO 3 phase (Fig. S4 and S5 †).…”

MXene-derived Ti3C2–Co–TiO2nanoparticle arraysviacation exchange for highly efficient and stable electrocatalytic oxygen evolution

“…S12 (ESI†) also detect (111) planes of metallic Co with a lattice spacing of ∼0.2 nm, as indicated within the yellow line region. 26 The lattice spacing of 0.237 nm can be assigned to the (311) plane of Co 3 O 4 , 27 consistent with the XPS results. Elemental mapping confirms that Ti and O elements are uniformly distributed throughout the LM–Co–TO NA (Fig.…”

Hierarchical porous carbon frameworks derived from Juncus effusus biomass with robust electromagnetic wave absorption properties

“…In particular, trace elements like Si, P, and K are believed to be instrumental in establishing the interface polarization by alternating EMW fields to improve the EMW absorption properties of materials due to the electronegativity difference with C atoms. 25,26 The chemical structures of JE and JE-700 were examined through FTIR spectroscopic analysis, as depicted in Fig. 2(A).…”