Rational Design of Hierarchical SiO₂@TiO₂ Composite with Large Internal Void Space for High-Performance Microwave Absorption

The design and development of excellent microwave absorption (MA) material is significant for healthcare, electronic, and security industries. Herein, a sophisticated composite with the advantages of large interlayer space, nanoparticles with small size, and hierarchical nanostructure (core@shell@void@shell configuration) simultaneously is demonstrated for the first time. Such unique SiO₂@TiO₂ nanoparticle was fabricated via a multi-step process. Associating maximum reflection loss value can reach –35.2 dB in certain frequency of 11 GHz and thickness of 3.0 mm. Small-sized TiO₂ nanoparticles (about 6 nm) in first coating and large gap between TiO₂ coating layers are significantly critical for the superior MA performance. Our work points a new direction to rationally construct high-performance microwave absorber.