Herein, we present a strategic approach to fabricate ultra-thin, structured electromagnetic interference (EMI) shielding films with Janus hydrophilic/hydrophobic surfaces, integrating polyetherimide (PEI) microsphere synthesis, silver (Ag) surface deposition, and solvent casting techniques. PEI microspheres with a diameter of ~4.78 μm are firstly synthesized via an emulsion technology. PEI@Ag composite films with a thickness of 25±5 μm were fabricated by conformal deposition of a dense silver shell through chemical plating and subsequently a micro-oscillation casting method. These films synergize ultra-thin dimensions with exceptional EMI shielding performance, which corresponds to an exceptional SE-to-thickness ratio (SE/d) of 1.2×10³ dB/mm, thereby highlighting the pronounced benefit derived from its ultra-thin architecture. Beyond shielding performance, these films demonstrate outstanding thermal stability, acid/alkali corrosion resistance, and efficient Joule heating conversion, coupled with remarkable flexibility and lightweight characteristics, while retaining the unique Janus wettability. Such multifunctional integration renders the films highly attractive for advanced EMI shielding applications in extreme outdoor environments, highlighting their potential as next-generation solutions for demanding engineering scenarios.

Perovskite barium titanate (BaTiO₃) demonstrates exceptional dielectric properties as a promising microwave-absorbing (MA) material. Leveraging structural flexibility of perovskites, magnetic components can be incorporated at A/B-sites to enhance MA performance, yet the fundamental disparity in MA mechanisms between A/B-site magnetic doping remains elusive. Herein, nickel-doped BaTiO₃ perovskites were systematically synthesized through precise adjustment of the Ba/Ti molar ratio to achieve both A-site (Ni_xBa_1−xTiO₃, N_xBTO) and B-site (BaTi_1−xNi_xO₃, BTN_xO) substitutions (0 ≤ x ≤ 0.1) via a simple one-step hydrothermal method. Notably, A-site Ni²⁺ substitution in N_xBTO induced superior magnetic loss (tanδ_μ = 0.39) attributed to eddy-current dissipation, while B-site doping in BTN_xO achieved higher dielectric loss (tanδ_ε = 0.49). The N_0.1BTO sample exhibited optimal MA performance with a remarkable minimum reflection loss (RL_min) of −44.39 dB and broad effective absorption bandwidth (EAB = 8.66 GHz) covering the Ku-band and 67% X-band. Multimodal analysis revealed synergistic interactions among multiple reflection and scattering, multi-polarization relaxation, natural resonance, and eddy currents. In contrast, BTN_0.01O demonstrated deeper RL_min (−50.88 dB) but narrower EAB (3.33 GHz) governed by dielectric mechanisms. Structural characterization indicated A-site doping induced lattice distortion, reduced unit-cell volume, and optimized oxygen vacancy distribution, synergistically balancing magneto-dielectric parameters. Conversely, B-site substitution increased oxygen vacancy concentration and carrier mobility while amplifying dielectric fluctuations. The spatial occupation preference of A/B dopants (A-site and B-site) governs lattice symmetry breaking, consequently establishing structure–property relationships and underpinning the material’s tunable dielectric behavior and magnetic phenomena. This work proposes a site-selective doping strategy for designing high-performance perovskite MA materials through magneto-dielectric equilibrium optimization.

With the escalating concerns over environmental pollution, effective management of industrial waste has emerged as a critical research focus in modern materials science. In this study, we developed cobalt-cobalt oxide doped lignin-based porous carbon materials (Co@CoO@MPC) by employing zeolitic imidazolate framework-67 (ZIF-67) decorated with industrial black powder—a byproduct rich in lignin and carbon. The synthesis involved potassium hydroxide (KOH)-assisted microwave activation, which enabled the creation of a porous structure, thereby markedly increasing the specific surface area and interfacial properties of the composites. During pyrolysis, ZIF-67 underwent transformation into cobalt (Co) and cobalt oxide (CoO) phases. The synergistic interaction between Co/CoO and the porous carbon significantly enhanced microwave absorption through both dielectric and magnetic loss mechanisms. The Co@CoO@MPC composites demonstrated exceptional microwave absorption properties across a broad frequency range, particularly at higher frequencies. Specifically, the sample after 2-min microwave irradiation exhibits a high EAB value of 5.7 GHz (1.6 mm thickness) and an RL_min value of −30 dB (2.0 mm thickness). This research not only offers an innovative approach to recovering resources from industrial black powder but also provides groundbreaking strategies for developing high-performance microwave-absorbing materials.

Herein, the electromagnetic shielding performance of surface concave-convex (SC) and zig-zag micro-arrays was studied by using a simulation prediction and a three-dimensional (3D) printing custom model. Firstly, surface stripe concave-convex (SSC) and surface cylindrical concave-convex (SCC) micro-arrays with or without zig-zag micro-arrays are designed, and their shielding performance is simulated in multi-bands (C-, X-band). The multiwalled carbon nanotubes/polydimethylsiloxane composites (MWCNT/PDMS) with different SC structures and different electrical conductivity are molded in acrylonitrile-butadiene-styrene copolymer (ABS) molds which are printed by a 3D printer. The results show that the electromagnetic interference shielding effectiveness (EMI SE) of the samples can be enhanced by constructing the SC micro-arrays with zig-zag micro-arrays, and improving with the increase of conductivity and frequency. In addition, the shielding mechanism of the SC-MWCNT/PDMS composites is investigated and discussed by an electromagnetic simulation.

Carbonized metallic organic frameworks (CMOF) have been attracting attention in microwave absorption (MA) research area because of their diverse structures, tunable compositions, and rich porosity. Herein, structure regulation on metal clusters in CMOF is achieved by tuning the interaction strength between metals and ligands to enhance microwave absorption performance. Due to relatively weak interaction among copper cations and ligands, copper nanoclusters (CuNC) can be uniformly formed and embedded within the cobalt/zinc (Co/Zn) CMOF. Firstly, copper cations are added to the Co/Zn bimetallic zeolitic imidazolate frameworks (ZIFs). Secondly, the CMOF composite particles with CuNCs (CuNCs/CoZn-CMOF) were developed by a pyrolysis process. The CuNCs/CoZn-CMOF with an appropriate amount of CuNCs can harmonize both dielectric and magnetic losses. As a result, the minimum reflection loss (RL_min) reaches –45.1 dB at a matching thickness of 2.30 mm and the effective absorption bandwidth (EAB) is 8.80 GHz at a thickness of 3.10 mm. The broadband response to electromagnetic waves is attributed to interfacial polarization at CuNCs surface and heterogeneous interfaces, impedance matching and multiple scattering of electromagnetic waves. This study provides a feasible method to develop CMOF microwave absorption materials with high EAB values.