Size-morphology control, surface reaction mechanism and excellent electromagnetic wave absorption characteristics of Fe3O4 hollow spheres

This paper designs and regulates unique monodisperse Fe3O4 hollow spheres through solvothermal method. Hollow structure provide light-weight property which is required for electromagnetic wave (EMW) absorbing materials. First and foremost, the size (700–350 nm) and surface of Fe3O4 hollow spheres can be adjusted by different urea contents, which realizes the morphology control of “big to small” and “smooth to rough”. Secondly, we select different reaction time to study how morphology of Fe3O4 hollow sphere changes, such as the flower-like (F6, 24 h). Thirdly, our work explores the relationship between morphology and property. In addition, the data shows the “double peaks” characteristic of EMW absorption. Overall, the sample F2 has the balance of bandwidth (4.56–9.24 GHz, 4.68 GHz), thickness (3.62 mm) and RL value (−56.90 dB, at 8.32 GHz), leading excellent performance. Finally, Fe3O4 hollow spheres may be widely applied not only in EMW absorption but also in energy storage, biomedical field, etc.