Enhancing surface polarization and reducing bandgap of BaTiO3 nanofiller for preparing dielectric traits-improved composites via its hybridization with layered g-C3N4

Polymer-based composites with high dielectric constant and low filler load are urgently desired for electrostatic energy storage. To increase dielectric constant of composites with low-content filler, in this work, we have employed a novel strategy of hybridization between BaTiO 3 (BTO) and graphitic carbon nitride (g-C 3 N 4 ) to fabricate ternary composites. First, g-C 3 N 4 @BTO hybrid-filler was synthesized. Then, two series of composite films namely poly(vinylidene fluoride-chlorotrifluoroethylene) (P(VDF-CTFE))/BTO binary composites and P(VDF-CTFE)/hybrid ternary composites were fabricated. Later, dielectric, conductive and breakdown properties of all composites were measured. Finally, density functional theory (DFT) calculations on interface of hybrid-filler were performed to verify high contribution of interface to high dielectric constant of ternary composites. Compared with binary composites, the reduced dielectric loss (@ 100 Hz) and breakdown strength of ternary composites are ascribed to low polymer/BTO interface leakage current and bandgap of hybrid-filler respectively. In ternary composite with 15 wt % hybrid, we detected a high dielectric constant of ∼72 at 100 Hz, low dielectric loss of ∼0.065 at 100 Hz and high breakdown strength of ∼215.8 MV m −1 . For the novelty, an excellent synergy between BTO and g-C 3 N 4 for dielectric applications has been found. This work might pave a road for fabricating promising composites for energy storage.