Novel hollow urchin-like /-MnO₂ boost microwave absorption

The synthesis of novel structural materials is one of the hot topics in advanced materials. Herein, the hollow urchin-like structure of manganese dioxide (MnO2) was synthesized via a one-step hydrothermal strategy, demonstrating exceptional microwave absorption properties. The multiphase MnO2 has a hollow urchin-like structure composed of alpha-MnO2 and gamma-MnO2, which exhibits outstanding impedance matching characteristics and favorable attenuation abilities. In the frequency range of 2-18 GHz, the hollow urchin-like alpha/gamma-MnO2 presents excellent microwave absorption with the minimum reflection loss (RLmin) of - 53.3 dB at 14.17 GHz with a thickness of only 1.9 mm, and the corresponding effective absorption bandwidth (EAB) can reach 5.45 GHz at the same thickness. Meanwhile, the hollow urchin-like alpha/gamma-MnO2 shows a practical microwave absorption capacity of approximately with EAB of 4.97 GHz at the ultrathin thickness of 1.5 mm via adjusting absorbent concentration. This study confirms the exceptional performance of the material in terms of its microwave absorption, providing valuable insights for the development of environmentally friendly, cost-effective, and high-performance materials.