Constructing and optimizing core-shell structured Co@TiO2 as highly efficient electromagnetic wave absorber

To achieve highly efficient electromagnetic wave absorber, elaborately designing magnetic-dielectric Co@TiO2 microspheres with core-shell configuration are successfully constructed through a facile sequential process of liquid phase reduction-sol-gel-annealing. Owing to the core-shell configuration and the synergistic effect among magnetic and dielectric components, the annealed sample shows outstanding electromagnetic wave absorption (EMA) in X and K-u band. Impressively, a maximum reflection loss (RLmax) is reached -56.6 dB at a coating thickness of 2.3 mm with corresponding effective absorption bandwidth (EAB(10)) of 7.2 GHz (including 65% of K-u band and 82.5% of X band), much stronger than those of as-prepared Co (EAB(10) of 1.6 GHz, RLmax of 14.6 dB) and pristine Co@TiO2 (EAB(10) of 2.9 GHz, RLmax of 16.3 dB). An EAB(10) covering completely the whole X and K-u band could be obtained by controlling the thickness only from 2.0 mm to 2.5 mm. The composites have both outstanding RL and wide EAB(10) with the thin coating thickness, reinforcing that fabricating core-shell configuration composites is an efficient strategy to boost the EMA efficiency.

Automated summary

By designing magnetic-dielectric Co@TiO2 microspheres with core-shell configuration, highly efficient electromagnetic wave absorber was constructed, showing outstanding absorption performance with a maximum reflection loss of -56.6 dB. By controlling the coating thickness, a complete coverage of the entire X and K-u band for effective absorption bandwidth can be achieved.