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.