p(C₃O₂)ₓ-derived defect‑rich 2D metal composites via multi‑metal doping for enhanced microwave absorption

The development of two-dimensional (2D) metal composite materials for electromagnetic wave (EMW) absorption is hindered by complex fabrication processes, high raw material costs, and insufficient absorption performance. We ingeniously integrate a multi-metal doping strategy with the oxygen-rich two-dimensional structure of p(C₃O₂)ₓ to successfully construct a defect-rich two-dimensional metal composite microwave absorber. Spectroscopic analysis reveals that multi-metal doping and oxygen release during pyrolysis generate abundant heterogeneous interfaces (oxides/alloys) and induce pronounced electron delocalization, promoting lattice distortions and defect formation. This synergistic effect significantly enhances both local dipole and interfacial polarization, boosting dielectric response. Consequently, the optimized OC-FeMnCuCo sample achieves exceptional EMW absorption with a minimum reflection loss (RL min ) of –55.0 dB and a broad effective absorbing bandwidth (EAB) of 6.8 GHz at an ultra-thin thickness of 1.9 mm. CST simulations further confirm its practical applicability. This work provides a simple, cost-effective strategy for designing advanced 2D absorbers.