Polymer-based dielectric composites are pivotal for advanced pulsed power and power electronics, yet synergistically enhancing dielectric constant and breakdown strength remains a formidable challenge. Herein, we report a controllable layer-by-layer spray assembly strategy to fabricate ordered multilayer polyetherimide (PEI)-based composites with alternating high-dielectric and high-insulation layers. Homologous carboxylated PEI (CPEI) was designed and covalently grafted onto boron nitride nanosheets (BNNS) and barium strontium titanate (BST) fillers, ensuring exceptional interfacial compatibility. This enabled the precise deposition of CPEI@BNNS/PEI and CPEI@BST/PEI layers, yielding 3-, 5-, and 7-layer films. The 7-layer film achieved a high dielectric constant of 7.43 at 1 kHz, a remarkable breakdown strength of 731.2 kV·mm^-1, and a record discharge energy density of 20.87 J·cm^-3—4.91 times that of pure PEI—while maintaining >90% charge-discharge efficiency. Comprehensive characterization and simulations revealed that the alternating multilayer structure creates deep-level interface traps that effectively suppress space charge migration, homogenize the internal electric field, and block electrical tree propagation. This work provides a facile and scalable pathway for the design and fabrication of high-performance ultrathin dielectric films.

The advancement of efficient and environmentally sustainable heterogeneous catalysts that facilitate the transformation of carbon dioxide (CO₂) into chemicals has gained considerable attention. In this study, we synthesized a carbon nitride (C₃N₄) functionalized with copper phthalocyanine (CuPc) and ionic liquid (IL) (C₃N₄-CuPc-IL) and employed it as an efficient catalyst enabling the cycloaddition of CO₂ with epoxides. The presence of urea/urethane groups, Cu²⁺ ions, and I⁻ ions that can effectively activate and open the epoxide ring was confirmed by Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), ultraviolet–visible (UV–vis) spectroscopy, thermogravimetric analysis (TGA), powder X-ray diffraction (XRD), and scanning electron microscopy (SEM). Meanwhile, the multiple nitrogen-containing structures (copper phthalocyanine, C₃N₄, and quaternary ammonium cationic structures) facilitated the adsorption and activation of CO₂. Consequently, C₃N₄-CuPc-IL demonstrated high catalytic efficiency for the cycloaddition between CO₂ and epoxides. Specifically, with 5.0 wt.% loading of C₃N₄-CuPc-IL catalyst under 2.0 MPa and 120 °C for 12 h, the yield of cyclic carbonate reached 98%. Additionally, the prepared catalyst demonstrated excellent structural stability and recyclability, alongside high catalytic activity toward various epoxides. Density functional theory (DFT) calculations indicated that the ring-opening reaction represents the rate-determining step in the C₃N₄-CuPc-IL catalyzed cycloaddition reaction, with an energy barrier of only 24.2 kcal/mol. The impressive catalytic performance of C₃N₄-CuPc-IL confirmed the synergistic catalytic effect of hydrogen bond donor groups, Lewis acidic sites, and ionic active sites in the CO₂ cycloaddition reaction, providing theoretical guidance for the design of CO₂ conversion catalysts.

Dielectric energy storage materials that are extensively employed in capacitors and other electronic devices have attracted increasing attentions amid the rapid progress of electronic technology. However, the commercialized polymeric and ceramic dielectric materials characterized by low energy storage density face numerous limitations in practical applications. In this study, we report the simultaneous enhancement of dielectric properties of poly(arylene ether nitrile) (PEN) through the incorporating of sulfonated PEN (SPEN) modified barium titanate nanorods (BTNR) (SPEN@BTNR) and hot-stretching. BTNR is synthesized using a two-step hydrothermal method, aminated with KH550, and then reacted with SPEN to form the cladding-modified SPEN@BTNR. Due to the intrinsic high permittivity of barium titanate (BT) and enhanced compatibility between SPEN@BTNR and PEN stemming from the cladding of SPEN, the dielectric constant and breakdown strength of SPEN@BTNR/PEN composite are as high as 14.0 at 10³ Hz and 198.1 kV/mm at the doping amount of 15 wt.%, respectively. As a result, the energy storage density of SPEN@BTNR/PEN is increased to 2.43 J/cm³, compared with that of 0.82 J/cm³ for PEN. In addition, derived from the rearrangement of SPEN@BTNR and orientation of PEN after hot-stretching, the dielectric constant and breakdown strength of SPEN@BTNR/PEN with 15 wt.% fillers are further enhanced to 17.1 and 204.8 kV/mm, respectively, resulting in an energy storage density of 3.36 J/cm³. The boosting of energy storage density up to 310% provides a new idea for improving the performances of dielectric energy storage materials.