Synthesis of porous Fe3O4-SnO2 core-void-shell nanocomposites as high-performance microwave absorbers

Porous Fe3O4-SnO2 core-void-shell nanocomposites with a porous Fe3O4 core and urchin-like SnO2 shell have been fabricated through the combined processes of modified stobber method with hydrothermal deposition technique. These nanocomposites can be maximize the interface areas between the core and shell that consume higher microwave energy, with the goal of improving the microwave absorption performance, i.e., of achieving strong reflection loss and wide effective bandwidth. The surface area and pore width distribution confirmed the mesoporous morphology of the porous Fe3O4-SnO2 core-void-shell nanocomposites. The microwave absorption analysis shows that the present porous Fe3O4-SnO2 core-void-shell nanocomposites with lower amount (30 wt%) in paraffin wax matrix exhibit very strong reflection loss peak of-66.5 dB (6.8 GHz) with the 3 mm absorber thickness, and have a wide effective absorbing bandwidth of 5.6 GHz (10.2-15.8 GHz). The high performance of nanocomposites can be attributed to the porous core-shell structure together with the void space. The interspace between the core and the shell can induce multiple reflections, interfacial polarization and even microwave plasma. Thus, we believe that a controlled porous structure in Fe3O4-SnO2 core-void-shell nanocomposites constitutes a novel approach to attain high-performance microwave absorbers in the field of electromagnetic wave absorption.