Design of Multi-Interface Hydrogenated Yolk–Shell C@TiO2 Microspheres With Enhanced Microwave Absorption Performances

Rational design on the microstructure and chemical composition is a feasible strategy to boost the performance of some conventional microwave absorbers. In this study, we designed and synthesized unique hydrogenated yolk–shell C@TiO₂ composites (C@TiO₂-H₂). The results indicate that the as-prepared composite can effectively modify the matching degree of characteristic impedance and dielectric loss property by high complex permittivity carbon cores, crystal/disorder microstructure of TiO₂ shells, and yolk–shell microstructure. The maximum reflection loss is −76.8 dB at 7.6 GHz with an absorber thickness of 3.0 mm. With an absorber thickness of 2.0 mm, the bandwidth over −10.0 dB is 4.5 GHz from 10.7 to 15.2 GHz. Notably, C@TiO₂-H₂ outperformed TiO₂, hydrogenated TiO₂ (TiO₂-H₂), carbon microspheres (C_m), as well as unhydrogenated yolk–shell C@TiO₂ (C@TiO₂-N₂) microspheres, where superior reflection loss and wide response bandwidth can be achieved simultaneously. Therefore, the yolk–shell C@TiO₂-H₂ microspheres are expected to be promising candidates for microwave absorption applications.