Hollow but perforated C/Co/Mo₂C cubes enhance electromagnetic absorption

The development of advanced electromagnetic (EM) wave absorbers is crucial for applications in stealth technology and EM interference shielding. A major challenge in this field is achieving high absorption efficiency across a broad frequency range while maintaining lightweight and structurally robust materials. In this study, we successfully developed a precise and flexible synthesis strategy to prepare hollow C/Co/Mo₂C cubes using Zn/Co(C₄O₄)(H₂O)₂ as a flexible template, which offers the advantages of simultaneous removal and easy control of metal Co content. The shell of the hollow cubes can be further optimized by changing the oxidizer content for polypyrrole (PPy). At optimum shell thickness and Co content, the C/Co/Mo₂C-0.4 composites, featuring hollow but perforated structures, exhibit superior EM wave absorption properties, with a minimum reflection loss (RL_min) of −73.46 dB and an effective absorption bandwidth (EAB) of 5.20 GHz at 2.0 mm with 15 wt% filler. Detailed investigations reveal that the hollow C/Co/Mo₂C-0.4 cubes provide polarization loss, conduction loss, magnetic loss, and optimal impedance matching characteristics, significantly enhancing EM wave absorption performance. This work offers a promising strategy for assembling multiple components into a hollow architecture, offering superior molybdenum carbide microwave absorbers.