PVP-encapsulated CoFe2O4/rGO composites with controllable electromagnetic wave absorption performance

Abstract

Nowadays, developing electromagnetic wave (EMW) absorbers with lightweight, broad bandwidth and strong absorbing capacity is of great importance in electromagnetic radiation issue. In this work, a novel PVP encapsulated CoFe2O4/rGO composite is designed and synthesized by a facile hydrothermal technique. Noticeably, by altering the additive amount of PVP, the microstructure and morphology of CoFe2O4/rGO@PVP ternary composites can be effectively tuned. A typical capsule structure with a length of about 140 nm and a diameter of about 90 nm is obtained, where CoFe2O4/rGO binary composite is covered by PVP. Further, the electromagnetic parameters of as-synthesized CoFe2O4/rGO@PVP samples can be adjusted well by changing the weight fraction of PVP. Particularly, when the mass ratio of PVP to Fe(NO3)3·9H2O is 2, a maximum reflection loss (RL) value at 15.7 GHz with a thin thickness of 1.96 mm is −56.8 dB, Meanwhile, its effective absorption bandwidth (RL < −10 dB) is 6.8 GHz (from 10.64 to 17.44 GHz) with a thickness of 2.2 mm. Considering the specific CoFe2O4/rGO@PVP capsule structure, the possible mechanism of the enhanced EMW absorption is deeply investigated. Herein, a new route to improve the microwave absorbing performance of rGO-based composites is presented. Owing to its excellent EMW absorption performance, the obtained CoFe2O4/rGO@PVP composite can be considered as a promising and suitable candidate for high-performance EMW absorbers.