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Vitrimer materials that obscure the line between ″thermoset″ and ″thermoplastic″ have already attracted a great deal of interest since they exhibit dynamic properties of stress relaxation or reprocessability without losing their permanently cross-linked networks. While much research has been aimed at developing new exchangeable dynamic bonds to broaden the scope, there is a dearth of effort in exploring the key factors that influence the dynamic properties of vitrimer materials. These explorations are not only useful in the exact design and synthesis of vitrimer materials but also quite important in their theory establishment and computer simulation. However, only a few ways including catalyst control have been confirmed to be the key factors in controlling the dynamic properties of classical vitrimer materials like the polyester-based epoxy vitrimer. Here, we proposed that the density of exchangeable ester bonds (υ) in networks also has a crucial role in adjusting the dynamic properties of epoxy vitrimers. Four polyester-based epoxy vitrimers were synthesized from the tricarboxylic acid curing agent and different epoxy monomers, resulting in various υ’s. These epoxy vitrimers were named ″E202-vitrimer″, ″E380-vitrimer″, ″E500-vitrimer″, and ″E640-vitrimer″ according to the different molecular weights of the epoxy monomer. It was revealed that the dynamic properties of these vitrimer materials varied with the υ value. From the E640-vitrimer to E202-vitrimer, the stress relaxation behavior sped up with the rise in υ and the characterized relaxation times (τ’s) obviously decreased. Meanwhile, the activation energy (E a) and the Arrhenius prefactor (τ0), which are two important intrinsic parameters in evaluating the dynamic properties of vitrimers, exhibited heavy dependence on υ, while linear models were applied to describe their relationships. Moreover, the τ at various temperatures could be also predicted from a linear model that relied on the υ in polyester vitrimers. These results indicated that υ has a crucial role in controlling the dynamic properties of polyester-based epoxy vitrimers and the value of υ could be applied to calculate the τ, E a, and τ0. Besides, the influence of υ on the dynamic properties of polyester-based epoxy vitrimers and the resulted models might be workable in other vitrimer materials, which can be utilized to design desired vitrimer materials for various applications.

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Porous carbon and metal oxides/sulfides prepared by using metal–organic frameworks (MOFs) as the precursors have been widely applied to the realm of supercapacitors. However, employing MOF‐derived metal phosphides as positive and negative electrode materials for supercapacitors has scarcely been reported thus far. Herein, two types of MOFs are used as the precursors to prepare CoP and FeP4 nanocubes through a two‐step controllable heat treatment process. Due to the advantages of composition and structure, the specific capacitances of FeP4 and CoP nanocubes reach 345 and 600 F g−1 at the current density of 1 A g−1, respectively. Moreover, a quasi‐solid‐state asymmetric supercapacitor is assembled based on charge matching principle by employing CoP and FeP4 nanocubes as the positive and negative electrodes, respectively, which exhibits a high energy density of 46.38 Wh kg−1 at the power density of 695 W kg−1. Furthermore, a solar‐charging power system is assembled by combining the quasi‐solid‐state asymmetric supercapacitor and monocrystalline silicon plates, substantiating that the device can power the toy electric fan. This work paves a practical way toward the rational design of quasi‐solid‐state asymmetry supercapacitors systems affording favorable energy density and long lifespan.

Layered double hydroxides (LDHs), as an effective oxygen evolution reaction (OER) electrocatalyst, face many challenges in practical applications. The main obstacle is that bulk materials limit the exposure of active sites. At the same time, the poor conductivity of LDHs is also an important factor. Exfoliation is one of the most direct and effective strategies to increase the electrocatalytic properties of LDHs, leading to exposure of many active sites. However, developing an efficient exfoliation strategy to exfoliate LDHs into stable monolayer nanosheets is still challenging. Therefore, we report a new and efficient solid-phase exfoliation strategy to exfoliate NiFe LDH and graphene oxide (GO) into monolayer nanosheets and the exfoliating ratios of NiFe LDH and GO can reach up to 10 and 5 wt %, respectively. Based on the solid-phase exfoliation strategy, we accidentally discovered that there is a dynamic evolution process between NiFe-LDH nanosheets (NiFe-LDH-NS) and GO nanosheets (GO-NS) to assemble new NiFe-LDH/GO nanohybrids, i.e., NiFe-LDH-NS could be horizontal bespreading on GO-NS or well-organized standing on GO-NS, or both simultaneously. The electrocatalytic OER property test results show that NiFe-LDH/RGO-3 (NFRG-3) nanohybrids obtained by the reduction treatment of NiFe-LDH/GO-3 (NFGO-3) nanohybrids, in which NiFe-LDH-NS are well-organized standing on GO-NS, have excellent electrocatalytic properties for OER in an alkaline solution (with a small overpotential of 273 mV and a Tafel slope of 49 mV dec–1 at the current density of 30 mA cm–2). The excellent electrocatalytic properties for OER of NFRG-3 nanohybrids could be attributed to the unique three-dimensional arraylike structure with many active sites. At the same time, reduced graphene oxide (RGO) with excellent conductivity can improve the charge-transfer efficiency and synergistically improve OER properties of nanohybrids.