Preparation and microwave absorption properties of uniform TiO₂@C core-shell nanocrystals

In this work, carbon-coated TiO₂ (TiO₂@C) core-shell nanocrystals have been synthesized by a simple acetylene decomposition method and further explored for the microwave absorbing application. Results demonstrate that a well-graphitized carbon layer with a thickness of about 3.5 nm can be uniformly coated on the surface of TiO₂. It is found that the microwave absorption properties of TiO₂@C are remarkably enhanced compared to the bare TiO₂. The optimal RL calculated from the measured complex permittivity and permeability is -58.2 dB at 7.6 GHz for TiO₂@C with a loading of 40 wt%. Whereas for TiO₂@C with a loading of 60 wt%, the effective bandwidth of less than -10 dB is found to reach 5.0 GHz with the coating thickness of 2.2 mm. The enhanced performance can be attributed to the increased dielectric properties and the multiple relaxation processes caused by the core-shell composite materials.