The hydrogen adsorption characteristics and mechanism of transition metal-doped zeolite template carbon (ZTC) as a novel porous material are studied by theoretical calculations employing first-principle all-electron atomic orbital method based on density functional theory. The stability of transition metal atoms (Sc, Ti, and V) decorated on zeolite template carbon is investigated by calculating the absorption binding energy. The adsorption configurations of the doped metal atom and adsorbed hydrogen are obtained from the energy functional minimization of first-principles calculations. The underlying mechanism for improving hydrogen storage performance of ZTC by doping transition metal atoms are explored through analyzing charge/spin populations of metal atoms in combination with the calculated results of hydrogen adsorption quantity and binding energy. To improve the hydrogen storage capability, the Sc, Ti, and V are individually introduced into the ZTC model according to the triplex axisymmetry. The hydrogen storage properties of ZTC decorated with different metal atoms are characterized by the adsorption energy and structure of several hydrogen atoms. The more energetically stable complex system with higher binding energy and adsorbing distance of hydrogen than lithium-doped ZTC can be achieved by doping Sc, Ti, V atoms in ZTC, which is expected to fulfill the substantial safe hydrogen storage by increasing hydrogen capacity with multi-sites doping of transition metal atoms. The present investigation provides a theoretical basis and predictions for the following experimental research and design of porous materials for hydrogen storage.

The interface area of nano-dielectric is generally considered to play an important role in improving dielectric properties, especially in suppressing space charge. In order to study the role of interface area on a microscopic scale, the natural charge and injected charge movement and diffusion on the surface of pure LDPE and SiO₂/LDPE nanocomposite were observed and studied by gradual discharge under electrostatic force microscope (EFM). It was detected that the charge in SiO₂/LDPE nanocomposite moved towards the interface area and was captured, which indicates that the charge was trapped in the interface area and formed a barrier to the further injection of charge and improving the dielectric performance as a result. Moreover, pulsed electro-acoustic (PEA) short-circuited test after charge injection was carried out, and the change of total charge was calculated. The trend of charge decay in the EFM test is also generally consistent with that in PEA short-circuit test and can be used to verify one another. The results revealed the law of charge movement and verified the interface area can inhibit space charge injection in nano-dielectric at the microscale, which provides an experimental reference for relevant theoretical research.

Nanodoping is an effective way to improve the dielectric properties and the aging resistance of polyethylene. Nano-zeolite has a nano-level porous structure and larger specific surface area than ordinary nano-inorganic oxide, which can be used to improve dielectric properties of low-density polyethylene (LDPE) nanocomposite. The zeolite/LDPE nanocomposites were prepared and subjected to thermal aging treatment to obtain samples with different aging time. Using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and the differential scanning calorimetry (DSC) test to study the microscopic and structure characteristics, it was found that nano-zeolite doping can effectively reduce the thermal aging damage to the internal structure of the nanocomposite; carbonyl and hydroxyl decreased significantly during the thermal aging time, and the crystallinity effectively improved. Nano-zeolite doping significantly improved the morphology and strengthened the aging resistance of the nanocomposite. In the dielectric strength test, it was found that nanodoping can effectively improve the direct current (DC) and alternating current (AC) breakdown field strength and the stability after the thermal aging. The dielectric constant of nanocomposite can be reduced, and the dielectric loss had no obvious change during the aging process. Moreover, the zeolite/LDPE nanocomposite with the doping concentration of 1 wt % had the best performance, for the nano-zeolite was better dispersed.

Nanocomposite doping is an effective method to improve the dielectric properties of polyethylene. Meanwhile, the introduction of thermal conductivity groups in crosslinked polyethylene (XLPE) is also an effective way to improve the thermal conductivity. Nano-zeolite is an inorganic material with a porous structure that can be doped into polyethylene to improve the insulation performance. In this paper, hyperbranched polyarylamide (HBP) with a high thermal conductivity and an auxiliary crosslinking agent (TAIC) was grafted on the surface of ZSM-5 nano-zeolite successively to obtain functionalized nano-zeolite (TAICS-ZSM-5-HBP) (the “S” in TAICS means plural). The prepared functionalized nano-zeolite was doped in polyethylene and grafted under a thermal crosslinking reaction to prepare nanocomposites (XLPE/TAICS-ZSM-5-HBP). The structural characterization showed that the nanocomposite was successfully prepared and that the nanoparticles were uniformly dispersed in the polyethylene matrix. The space charge of the TAICS-ZSM-5-HBP 5wt% nanocomposite under a high electric field was obviously inhibited. The space charge short-circuit test showed that the porous structure of the nano-zeolite introduced more deep traps, which made the trapped charge difficult to break off, hindering the charge injection. The introduction of TAICS-ZSM-5-HBP particles can greatly improve the thermal conductivity of nanocomposites. The thermal conductivity of the XLPE/5wt% and XLPE/7wt% TAICS-ZSM-5-HBP nanocomposites increased by 42.21% and 69.59% compared to that of XLPE at 20 °C, and by 34.27% and 62.83% at 80 °C.

The purpose of this paper is to study the effect of nano-bismuth ferrite (BiFeO₃) on the electrical properties of low-density polyethylene (LDPE) under magnetic-field treatment at different temperatures. BiFeO₃/LDPE nanocomposites with 2% mass fraction were prepared by the melt-blending method, and their electrical properties were studied. The results showed that compared with LDPE alone, nanocomposites increased the crystal concentration of LDPE and the spherulites of LDPE. Filamentous flake aggregates could be observed. The spherulite change was more obvious under high-temperature magnetization. An agglomerate phenomenon appeared in the composite, and the particle distribution was clear. Under high-temperature magnetization, BiFeO₃ particles were increased and showed a certain order, but the change for room-temperature magnetization was not obvious. The addition of BiFeO₃ increased the crystallinity of LDPE. Although the crystallinity decreased after magnetization, it was higher than that of LDPE. An AC test showed that the breakdown strength of the composite was higher than that of LDPE. The breakdown strength increased after magnetization. The increase of breakdown strength at high temperature was less, but the breakdown field strength of the composite was higher than that of LDPE. Compared with LDPE, the conductive current of the composite was lower. So, adding BiFeO₃ could improve the dielectric properties of LDPE. The current of the composite decayed faster with time. The current decayed slowly after magnetization.

This study successfully fabricated the quaternary topological insulator thin films of Bi_1.2Sb_0.8Te_0.4Se_2.6 (BSTS) with a thickness of 25 nm, improving the intrinsic defects in binary topological materials through doping methods and achieving the separation of transport characteristics between the bulk and surface of topological insulator materials by utilizing a comprehensive Physical Properties Measurement System (PPMS) and Terahertz Time-Domain Spectroscopy (THz-TDS) to extract electronic transport information for both bulk and surface states. Additionally, the dielectric polarization behavior of BSTS in the low-frequency (10–10⁷ Hz) and high-frequency (0.5–2.0 THz) ranges was investigated. These research findings provide crucial experimental groundwork and theoretical guidance for the development of novel low-energy electronic devices, spintronic devices, and quantum computing technology based on topological insulators.