Yan Shang

In this study, benzophenone compounds substituted with electron-withdrawing groups (-NO₂, -F, and -Cl) and electron-donating groups (-OH, -CH₃, -NH₂, and -OCH₃) were employed as voltage stabilizers for crosslinked polyethylene (XLPE) insulation materials. At B3LYP/6-311+G(d,p) level, reaction Gibbs free potential energy data for eleven reaction channels and molecular characteristics, including electron affinity EA(s), ionization potential IP(s), and HOMO-LUMO gap (E_g) of benzophenone derivatives, were obtained. The effects of electron-donating and electron-withdrawing functional groups were systematically evaluated. The calculated results indicate that benzophenones exhibit the lowest Gibbs free energy barrier for grafting onto polyethylene among the investigated molecules. With the introduction of electron-donating groups, the reaction Gibbs free energy barrier increases. It is worth noting that 2-Nitrobenzophenone is considered to possess superior electrical resistivity, attributed to its highest electron affinity among the studied compounds. This investigation is expected to provide reliable insights for the development of modified polyethylene-based insulating materials for high-voltage cables.

Cross-linked polyethylene (XLPE) insulation is used in most advanced power cable technology. However, in traditional cross-linking, the conductivity of the cross-linking system sharply increases due to the presence of additives (antioxidants and cross-linked agents). Therefore, reducing the number of antioxidants to further reduce conductivity is a very promising method. The structural design of a new dual-functional antioxidant 5-allyloxy-2-hydroxyl-3-tert-butylbenzophenone (5ATB) has been established. The antioxidant behavior and grafting reaction of 5ATB after photocatalysis under ultraviolet (UV) conditions were further studied using density functional theory (DFT). The reaction potential energy information of the six reaction channels at the B3LYP/6-311+G(d,p) level were obtained. The calculation results indicated that the reaction Gibbs energy barrier of 5ATB with O₂ is approximately 0.48 eV lower than that of the polyethylene chain with O₂ to achieve an anti-oxidative effect. Furthermore, the reaction-active site of 5ATB accepting H is located on the C of CH₂ in a C=C double bond, as demonstrated by an analysis of NBO charge populations. The proposed mechanism has the potential to further expand the design concept of insulation materials for advanced future power cables.

The effect of electron-donating and electron-withdrawing groups grafted onto polyethylene on electron mobility was studied using density functional theory. In order to ensure the accuracy of the calculation results, 17 basis sets from six methods were screened. 3-methylpentane was selected as the cross-linked polyethylene model. Compared with the experimental values, the theoretical calculation results show that wB97XD/6-311G(d,p) is more suitable for studying the electron mobility system. The roles of electron-donating and electron-withdrawing functional groups were studied. The results show that the electron mobility of grafting nitrobenzene (Ebnb) to polyethylene is the smallest among the studied molecules. As the ability of electron-donating groups increases, the electron mobility gradually increases, while the addition of the electron-withdrawing group reduces the electron mobility and the electron mobility gradually increases with increasing temperature. This investigation is expected to provide reliable information for the development of insulation materials for cables.

Cross-linked polyethylene (XLPE) is applied in most advanced high-voltage direct-current (HVDC) power cable insulations, which are produced via dicumyl peroxide (DCP) technology. The electrical conductivity of insulation material can be increased by cross-linking byproducts from the DCP process. Hence, currently much attention is being paid to a new process to produce cross-linking byproduct-free XLPE. The cross-linking in situ between ethylene–glycidyl methacrylate copolymer and 1,5-disubtituted pentane via reactive compounding is a substitute for DCP. The reaction potential energy information of the eighteen reaction channels was obtained at the B3LYP/6-311+G(d,p) level. Results demonstrated that epoxy groups and 1,5-disubtituted reactive groups can react in situ to realize the XLPE-based network structure via covalent linking, and epoxy ring openings yielded ester. 1,5-disubtituted pentane played a cross-linker role. The reactivity of the carboxyl group was stronger than that of the sulfydryl or hydroxyl group. The reaction channel RTS1 was more kinetically favorable due to the lower reaction Gibbs energy barrier height of 1.95 eV. The cross-linking network construction of the new XLPE insulation without byproducts opens up the possibility of DCP substitution, which is beneficial to furthering the design of thermoplastic insulation materials for power cables in the future.

An FePc/CeO₂ heterojunction is constructed by hydrogen bonding induced assembly and follows the Z-scheme mechanism of effective charge separation. Fe²⁺ in FePc promotes O₂ activation, thus enhancing the photocatalytic degradation of 2,4-DCP.

A series of double-layer Fe_n/C₆₀-GNR (n = 2, 4) devices have been designed and their transport characteristics have been thoroughly investigated. Theoretical guidance is provided for optimising the transport characteristics.

A series of four-terminal V₇(Bz)₈-WGNR devices were established with wrinkled graphene nanoribbon (WGNR) and vanadium-benzene nanowire (V₇(Bz)₈). The spin-polarized V₇(Bz)₈ as the gate channel was placed crossing the plane, the concave (endo-positioned) and the convex (endo-positioned) surface of WGNR with different curvatures via Van der Waals interaction. The density functional theory (DFT) and nonequilibrium Green’s function (NEGF) methods were adopted to calculate the transport properties of these devices at various bias voltages (V_S) and gate voltages (V_G), such as the conductance, spin-polarized currents, transmission spectra (TS), local density of states (LDOS), and scattering states. The results indicate that the position of V₇(Bz)₈ and the bending curvature of WGNR play important roles in tuning the transport properties of these four-terminal devices. A spin-polarized transport property is induced for these four-terminal devices by the spin-polarized nature of V₇(Bz)₈. Particularly, the down-spin channel disturbs strongly on the source-to-drain conductance of WGNR when V₇(Bz)₈ is endo-positioned crossing the WGNR. Our findings on the novel property of four-terminal V₇(Bz)₈-WGNR devices provide useful guidelines for achieving flexible graphene-based electronic nanodevices by attaching other similar multidecker metal-arene nanowires.