Rationally controlling interfaces and oxygen vacancies of CeO2@C core–shell nanorods/nanofibers for superior microwave absorption and thermal conduction

[Display omitted] •Controllable preparation of CeO2@C core–shell nanorods/nanofibers.•Optimizing the composition, structure, and properties of the composites.•A synchronous enhancement of heat conductance and EMW absorption.•Revealing the interfaces and oxygen vacancy dependent of performance. High-performance thermally conductive-microwave absorbing integrated materials are highly required to mitigate the severe electromagnetic pollution and overheating generated in electronic devices. However, the incompatibility between thermal conduction and microwave absorption impedes their collaborative development. Herein, an adjustment strategy for interface- and oxygen-vacancy-linkage was adopted to rationally construct CeO2@C core–shell nanorods/nanofibers (CSNRs/NFs) and cooperatively boost their electrical, thermal, and microwave absorption properties. A hydrothermal-annealing technique was employed to synthesize CeO2@C CSNRs/NFs. Their core–shell structure, oxygen vacancies/lattice defects, and length-to-diameter ratio were accurately adjusted by changing the annealed temperature (Ta) and toluene volume (V). The CeO2@C CSNRs/NFs produced under Ta = 600 °C and V = 1.5 mL exhibit high thermal conductivity (TC = 2.94 W/(m·K)) at a small load of 40 wt%. The large TC is mainly due to the weak phonon defect/interface scattering and electron/phonon co-transfer in a 3D continuous path consisting of a 1D structure. Furthermore, the CeO2@C CSNRs/NFs display strong microwave absorption (EABmax/d = 3.27 GHz/mm; RLmin=− 50.98 dB) due to their various polarizations, tunable conduction loss, and multiple internal reflections. These results demonstrate that the CeO2@C CSNR/NFs are an ideal multifunctional material that protects against concurrent EM interference and excess heat in electronic packaging materials.