To meet the requirements for electromagnetic wave (EMW) absorbing materials in corrosive environments such as the ocean, (NiZnCuMn)Co₂O₄ medium-entropy oxides (MEOs) with anticorrosion properties have been developed as novel EMW absorbing materials. The (NiZnCuMn)Co₂O₄ MEOs, which are synthesized via a hydrothermal reaction followed by calcination, exhibit robust EMW absorption performance with a minimum reflection loss of −64.05 dB and an ultrabroad effective absorption bandwidth that can reach 7.35 GHz by adjusting the hydrothermal reaction time. This high performance is attributed to the synergistic effect of dielectric loss, magnetic loss, and the unique structure of the MEOs. (NiZnCuMn)Co₂O₄ can be doped into epoxy resin, endowing it with excellent anti-corrosion properties. After being soaked in 3.5 wt.% NaCl for 14 days, (NiZnCuMn)Co₂O₄ prepared with a hydrothermal time of 12 h, shows a minimum corrosion current of 6.61 × 10⁻⁶ A/cm². When the hydrothermal time is 18 h, the corrosion current is 6.66 × 10⁻⁶ A/cm² and the corrosion potential reaches −0.712 V. This study provides new insights into the design of EMW absorbing materials with anticorrosion properties.

The development of multifunctional composites with desirable electromagnetic wave absorption and antibacterial performance for the medical field has aroused wide interest. In this work, SiOC/Ag composites were successfully fabricated via the liquid-phase method. When the filler content of SiOC/Ag-3 is 40 wt%, SiOC/Ag-3 exhibits excellent electromagnetic wave absorption performance, achieving a minimum reflection loss (RL_min) value of −58.03 dB with a matching thickness of only 2.82 mm. The superior electromagnetic wave absorption performance is attributed to (i) multiple reflections, (ii) conductive loss, and (iii) interfacial polarization loss. In addition, the radar cross-section (RCS) simulation indicates that all RCS values of the perfect electric conductor (PEC) with the SiOC/Ag-3 coating are below −20 dB·m² across the incident angle range from −60° to 60°, indicating strong radar stealth performance. Moreover, SiOC/Ag composites also achieve excellent antibacterial ability against E. coli and S. aureus through the generation of reactive oxygen species (ROS) under visible light irradiation. This work provides new insights into the design and development of bifunctional composites with electromagnetic wave absorption and antibacterial performance for application in medical devices.

SiOC-based ceramics are considered promising electromagnetic wave-absorbing materials because of their lightweight, high-temperature resistance, and heat insulation properties. Herein, SiOC@C ceramic nanospheres were prepared using a liquid-phase method combined with a polymer-derived ceramic (PDC) method, followed by heat treatment in N₂ and Ar atmospheres at different temperatures. The morphology, microstructure, phase composition, and electromagnetic wave absorption performance of the SiOC@C ceramic nanospheres were investigated in detail. The SiOC@C ceramic nanospheres obtained in the Ar atmosphere showed a minimum reflection loss (RL_min) of −67.03 dB, whereas the SiOC@C ceramic nanospheres obtained in the N₂ atmosphere exhibited an RL_min value of −63.76 dB. The outstanding electromagnetic wave absorption performance of the SiOC@C ceramic nanospheres was attributed to the synergistic effect between conductive loss, interfacial/defect polarization loss, multiple reflections, and scattering. Therefore, this research provides valuable insights into the design and fabrication of SiOC ceramic-based electromagnetic wave absorbers.

The development of low-cost, stable, and robust non-noble metal catalysts for water oxidation is a pivotal challenge for sustainable hydrogen production through electrocatalytic water splitting. Currently, such catalysts suffer from high overpotential and sluggish kinetics in oxygen evolution reactions (OERs). Herein, we report a "continuous" single-crystal honeycomb-like MXene/NiFeP_x–N-doped carbon (NC) heterostructure, in which ultrasmall NiFeP_x nanoparticles (NPs) encapsulated in the NC are tightly anchored on a layered MXene. Interestingly, this MXene/NiFeP_x–NC delivers outstanding OER catalytic performance, which stems from "continuous" single-crystal characteristics, abundant active sites derived from the ultrasmall NiFeP_x NPs, and the stable honeycomb-like heterostructure with an open structure. The experimental results are rationalized theoretically (by density functional theory (DFT) calculations), which suggests that it is the unique MXene/NiFeP_x–NC heterostructure that promotes the sluggish OER, thereby enabling superior durability and excellent activity with an ultralow overpotential of 240 mV at a current density of 10 mA·cm⁻².