Multifunctional polymer composites with both high dielectric constants and high thermal conductivity are urgently needed by high-temperature electronic devices and modern microelectromechanical systems. However, high heat-conduction capability or dielectric properties of polymer composites all depend on high-content loading of different functional thermal-conductive or high-dielectric ceramic fillers (every filler volume fraction ≥ 50%, i.e., f_filler ≥ 50%), and an overload of various fillers (f_{thermal-conductive filler} + f_{high-dielectric filler} > 50%) will decrease the processability and mechanical properties of the composite. Herein, series of alumina/barium titanate/polypropylene (Al₂O₃/BT/PP) composites with high dielectric- and high thermal-conductivity properties are prepared with no more than 50% volume fraction of total ceramic fillers loading, i.e., f_fillers ≤ 50%. Results showed the thermal conductivity of the Al₂O₃/BT/PP composite is up to 0.90 W/m·K with only 10% thermal-conductive Al₂O₃ filler, which is 4.5 times higher than the corresponding Al₂O₃/PP composites. Moreover, higher dielectric strength (E_b) is also found at the same loading, which is 1.6 times higher than PP, and the Al₂O₃/BT/PP composite also exhibited high dielectric constant ( ${\epsilon }_{\mathrm{r}}$ = 18 at 1000 Hz) and low dielectric loss (tan δ ≤ 0.030). These excellent performances originate from the synergistic mechanism between BaTiO₃ macroparticles and Al₂O₃ nanoparticles.

Mono‐dispersed ceria (CeO ₂ ) hollow nanospheres about 400 nm have been prepared via a facile one‐step hydrothermal method, wherein cerium nitrate hexahydrate (Ce(NO ₃ ) ₃ ·6H ₂ O) was used as cerium sources with the assistance of polyvinylpyrrolidone (PVP) in the ethylene glycol aqueous solution. X‐ray diffraction, X‐ray photoelectron spectra, scanning electron microscope, transmission electron microscope, nitrogen adsorption–desorption and Fourier transform infrared results indicate that PVP can improve the dispersion and control the morphology and sizes of CeO ₂ hollow nanospheres as a surfactant, and the internal diameter of CeO ₂ hollow nanosphere gradually increases with reaction time. Based on the time‐dependent experiment, the formation mechanism was proposed and discussed. These CeO ₂ hollow nanospheres show an excellent adsorption rate of heavy metal ions for Cr(VI) and the adsorption rate is about 70%. The CeO ₂ hollow nanospheres also had exhibited superior performance in the degradation of methyl orange dye.