As a transparent semiconductor, indium oxide (In₂O₃) exhibits intrinsically low dielectric parameter, rendering it ineffective for microwave absorption. Overcoming its inherent wide bandgap and limited dielectric loss to achieve effective microwave absorption presents a significant challenge. Herein, a lattice defect engineering strategy is proposed to construct oxygen vacancy-rich indium oxide (In₂O_3-x) and carbon-doped indium oxide (In₂O_3-x/C) particles with extrinsic defects. This approach achieves a breakthrough in the effective absorption bandwidth (EAB) of pristine In₂O₃, expanding it from 0 to 3.7 GHz. Furthermore, this study discovers that higher 1,2-benzisothiazoline-3-one dosages increase the oxygen vacancy concentration in In₂O_3-x/C, which is crucial for the material to exhibit microwave absorption capabilities. In particular, the In₂O_3-x/C-0.3 sample demonstrates enhanced microwave absorption through the synergistic effect of carbon doping, achieving a broad EAB of 5.0 GHz. Density Functional Theory calculations further reveal that the introduction of oxygen vacancies and carbon doping can optimize the band structure, reduce the bandgap and induce internal charge redistribution, thereby enhancing the conductive and polarization losses. This research is expected to open up a new avenue in the field of microwave absorption for In₂O₃ applications.

N-heterocyclic carbene (NHC) polymers, characterized by abundant nitrogen sources, tunable metal centers and excellent chemical stability, serve as ideal precursors for metal-incorporated N-doped carbon materials. Herein, ligand engineering and temperature-induced strategies are employed to fabricate NHC-derived N/metal dual-doped carbon materials (CN-X-700, X = Cu, Cu/Co, and Co) with two-dimensional nanoribbon morphology. The optimized carbonization temperature endows CN-X-700 with substantial N-doping levels, numerous defects and moderate electrical conductivity. These structural advantages balance polarization and conductive losses, thereby elevating dielectric dissipation. More importantly, the Cu/Co bimetallic heterointerfaces significantly improve the electromagnetic wave (EMW) absorption capability by combining impedance matching and multiple synergistic losses, including magnetic loss, interfacial polarization and conductive loss. The comparison shows that CN-Cu/Co-700 exhibits superior loss capacity and a broad absorption range, with a minimum reflection loss (RL_min) of −62.24 dB and an effective absorption bandwidth (EAB) covering 7.11 GHz (10.53–17.64 GHz). This study reveals the intrinsic relationship between heterointerfaces, multi-loss mechanisms and EMW dissipation, providing a novel structural regulation strategy for designing high-performance carbon-based microwave absorbers.

Rapid advancements in flexible electronics and military applications necessitate high-performance electromagnetic wave (EMW) absorbers. While huge breakthroughs in achieving high-attenuation microwave absorption, conventional EMW absorbing materials have single function and ambiguous absorption mechanisms. Herein, numerous gel-type absorbers are fabricated by introducing “regulators” into poly(acrylamide-co-acrylic acid) (P(AM-co-AA)) networks through radical polymerization in a glycerol-water mixed solvent. The dielectric constant and EMW absorption performance of the gels are precisely predicted by adjusting monomer concentration, the ratio of glycerol/water, and the content of the regulators. Notably, A₆G₂₀T₂₀-2 exhibits promising absorption performance with a minimum reflection loss (RL_min) of –33.8 dB at 12.4 GHz. The effective absorption bandwidth (EAB) covers the entire X-band (8.2–12.4 GHz) at a thickness of 2.7 mm. A₆G₂₀T₂₀-2 also has sensitive deformation responses and excellent tensile strength, adhesiveness, self-healing and anti-freezing properties. Overall, this work not only provides insight into the polarization loss mechanism of the gels as the result of high correlation between EMW absorbing properties and molecular polarization, but also offers an important reference for developing functional protective materials because of the rich functionalities and efficient protective capabilities of the gels.