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[Display omitted] • Core-shell NiC 2 O 4 @C/N-doped NiCoZn-LDH(NCO@C/N-LDH) structure was prepared by two-step hydrothermal process. • Carbon and nitride were directly doped into NiCoZn-LDH nanosheets as shell. • The assembled NCO@C/N-LDH//AC devices provided high energy storage capability. Layered double hydroxides (LDHs) are promising cathode materials for supercapacitors due to high theoretical specific capacitance and unique layered structure. Constructing hierarchical core–shell structure for the multicomponent LDHs is an effective strategy to further utilize them. Herein, a novel hierarchical core–shell structure (NCO@C/N-LDH) was fabricated by direct-doping of C and N species into NiCoZn-LDH nanosheets (C/N-LDH) coved on NiC 2 O 4 (NCO) arranged on the nickel foam via two-step hydrothermal method. The NCO as a backbone prevented C/N-LDH nanosheets from collapsing in charge/discharge process, while the C/N-LDH shell provided abundant active sites and exclusive access to electron/ion transport for accelerating the Faradaic reaction kinetics. The optimal NCO@C/N-LDH (2.0) displayed a remarkable electrochemical performance with a high specific charge of 1841.0C/g at 1 A/g and good rate capability. Furthermore, the as-fabricated NCO@C/N-LDH//AC device delivered a high energy density of 56.9 Wh kg−1 at power density of 800 W kg−1. [ABSTRACT FROM AUTHOR]

Layered double hydroxides (LDH) are regarded as promising electrode materials for supercapacitors due to their abundance, multiple oxidation states, and high theoretical capacitance. However, the limited active sites and dull reaction kinetics restrict their commercialization. In this work, the 3D hierarchical N-doping ZnCo-LDH array on nickel foam (NF) as an electrode material (N-ZnCo-LDH) was designed and directly fabricated via a hydrothermal method using 2-Methylimidazole as a nitrogen source. Consequently, the N-doping confined the growth of the N-ZnCo-LDH to form ultrathin nanosheets, which exposed more redox reaction active sites and facilitated the charge transfer, resulting in the enhancement in charge storage capacity. As a result, the optimal N (0.5) -ZnCo-LDH achieved a high specific charge of 942.6 C g−1 at 1.0 A g−1, excellent charge-discharge rate property (68.9% retention) and long durability (84.1% after 5 000 cycles). Also, the hybrid supercapacitor (N-ZnCo-LDH//AC) was fabricated employing N (0.5) -ZnCo-LDH as anode and activated carbon (AC) as cathode, which achieved an energy density of 29.2 Wh kg−1 at a power density of 750.0 W kg−1, and excellent cycling stability (84.0% retention after 10,000 cycles), which highlighted the potential of the N (0.5) -ZnCo-LDH electrode material towards practical application of supercapacitors. [Display omitted] • The ultrathin N-doped ZnCo-LDH nanosheets were synthesized using 2-Methylimidazole as nitrogen source. • N-doping confined the growth of the nanosheets, making them smaller and thinner. [ABSTRACT FROM AUTHOR]

Due to the inherent defect of flammability of polypropylene (PP), a novel and highly efficient carbon microspheres@layered double hydroxides@copper lignosulfonate (CMSs@LDHs@CLS) flame retardant was designed and prepared, which was attributed to the strong electrostatic interaction between carbon microspheres (CMSs), layered double hydroxides (LDHs) and lignosulfonate as well as the chelation effect of lignosulfonate on copper ions, and then it was incorporated into the PP matrix. Significantly, CMSs@LDHs@CLS not only observably improved its dispersibility in PP matrix, but also simultaneously achieved excellent flame retardant properties for composites. With the addition of 20.0 % CMSs@LDHs@CLS, the limit oxygen index of CMSs@LDHs@CLS and PP composites (PP/CMSs@LDHs@CLS) reached 29.3 % and achieved the UL-94 V-0 rating. Cone calorimeter tests indicated that the peak heat release rate, total heat release and total smoke production of PP/CMSs@LDHs@CLS composites exhibited declines of 28.8 %, 29.2 % and 11.5 %, respectively, compared with those of PP/CMSs@LDHs composites. These advancements were attributed to the better dispersibility of CMSs@LDHs@CLS in PP matrix and illustrated that CMSs@LDHs@CLS observably reduced fire hazards of PP. The flame retardant property of CMSs@LDHs@CLS might relate to condensed phase flame retardant effect of char layer and catalytic charring of copper oxides. [ABSTRACT FROM AUTHOR]

In this paper, a functionalized layered double hydroxide (LDH-LS@Ni(OH) 2) flame retardant was designed and fabricated based on a multi-modifier system consisting of lignosulfonate (LS) and Ni(OH) 2 and used as a novel flame retardant for polypropylene (PP). In this multi-modifier system, LS as a compatibilizer and charring agent to improve compatibility and char yield, and Ni(OH) 2 was utilized to improve the graphitization of char residual, resulting in a PP/LDH-LS@Ni(OH) 2 composite with higher thermal stability. With the addition of LDH-LS@Ni(OH) 2 was only 15 wt%, the PP/LDH-LS@Ni(OH) 2 composite achieved a limiting oxygen index (LOI) of 30.8% and passed the UL-94 V-0 rating. At the same time, the peak heat release rate (PHRR), total heat release (THR), and total smoke production (TSP) were significantly reduced by 62.7%, 29.5%, and 46.2%, respectively. The flame retardant properties of LDH-LS@Ni(OH) 2 were mainly due to the catalytic charring effect of the transition metal elements and the physical barrier effect of the hydrotalcite. More specifically, as a highly efficient flame retardant, LDH-LS@Ni(OH) 2 has promising potential in reducing the fire hazards of PP composites. [Display omitted] • The dual modified LDH flame retardant was synthesized by co-precipitation method. • A novel hybrid flame retardant of S/Ni-containing (LDH-LS@Ni(OH) 2) was prepared. • PP/LDH-LS@Ni(OH) 2 (15 wt%) increased the LOI to 30.8% and passed the UL-94 V-0 rating. [ABSTRACT FROM AUTHOR]

To overcome the flammable defects of polypropylene (PP) and expand its application in more fields, it is imperative to develop PP composites with fire retardance, smoke suppression, and mechanical strength. Here, inspired by the structure of the dandelion flowers, a core-shell CMSs@LDHs flame retardant was prepared by growing LDHs nanoflakes on the surface of CMSs to combine the excellent flame retardancy of CMSs with the advanced smoke suppression of LDHs, and then it was applied into PP matrix through melt blending to satisfy the fire safety requirements of PP. With the addition of 20 wt% CMSs@LDHs, the PP/CMSs@LDHs composite passed the vertical combustion tests (UL-94) V-0 rating, and its limiting oxygen index (LOI) value of it also reached 28.9 %. The peak heat release rate (PHRR), total heat release (THR), and total smoke production (TSP) of the PP/CMSs@LDHs were also decreased by 46.5 %, 30.8 %, and 11.9 %, respectively, compared with those of the Neat PP. [Display omitted] • The synthetic raw materials of CMSs are renewable. • The core-shell structure was synthesized based on the flower structure of dandelion. • CMSs act as the carrier of LDHs and promote the dispersion of LDHs. • LOI of PP/CMSs@LDHs (20 wt%) reached 28.9 % and samples can pass the UL-94 V-0 rating. [ABSTRACT FROM AUTHOR]

In this paper, an interlayered/surface-modified flame retardant (LDHs@PA-MEL) was prepared via a one-pot method with phytic acid (PA), melamine (MEL), and layered double hydroxides (LDHs-C) and used as a novel flame retardant for polypropylene (PP). In LDHs@PA-MEL, PA and MEL self-assembled to form a PA-MEL supramolecular network for functionalization on the surface of LDHs-C, and phytate anions intercalated into the interlayer. The extreme dispersibility of LDHs@PA-MEL in PP is attributed to the dual modification of PA and MEL. With the addition of 20 wt%, the PP/LDHs@PA-MEL composites achieved the limiting oxygen index (LOI) of 29.6%, whereas the PP/LDHs-C composites exhibited only LOI of 24.8%. The peak heat release rate (PHRR), total heat release (THR) and total smoke production (TSP) for PP/LDHs@PA-MEL were 409 kW∙m−2, 70.3 MJ∙m−2, and 7.1 m2, respectively, which presented declines of 63.5%, 26.2% and 43.7% compared with those of Neat PP. The flame retardancy of LDHs@PA-MEL was mainly due to catalytic charring, release of non-combustible gases, and physical barrier effects. More specially, this work provides a feasible method for the preparation of high-performance PP composites. [Display omitted] • The flame retardant was synthesized by interlayered/surface dual modified LDHs. • A novel and renewable flame retardant of P/N-containing (LDHs@PA-MEL) was prepared. • One-pot method provided a feasible idea for efficient preparation of modified LDHs. • PP/LDHs@PA-MEL (20 wt%) increased the LOI to 29.6% and passed the UL-94 V-0 rating. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel hierarchical CMSs@LDH@PZN nanospheres with double shells are synthesized. • CMSs@LDH@PZN has well compatible and outstanding thermostability in PP. • CMSs@LDH@PZN enhances the flame retardancy and toxic smoke suppression of PP. Developing advanced performance polypropylene (PP) composites with less smoke, eco-friendly and efficient flame retardants (FRs) has been a growing focus of research. In particular, it was significant to reduce the emissions of smoke and toxic gases generated during the burning of PP so that it meets green and safe industrial requirements. In this work, a CMSs@LDH@PZN hierarchical core–shell framework was designed and synthesized by using carbon microspheres (CMSs) and layered double hydroxides (LDHs) nanosheets connected to CMSs by electrostatic forces with polyphosphazene (PZN). The structure, composition and morphology of CMSs@LDH@PZN were characterized by SEM, TEM, FT-IR, XRD and TG, and the results were shown the triumphant preparation of the well-designed hierarchical core–shell structure CMSs@LDH@PZN. Additionally, the total smoke production, peak heat release rate and total heat release rate of PP/CMSs@LDH@PZN composites were decreased by 56.2%, 41% and 43.4%, respectively. With the addition of 20 wt% CMSs@LDH@PZN alone, the PP/CMSs@LDH@PZN composites reached a V-0 rating in the Vertical combustion tester (UL-94), and had a limiting oxygen index (LOI) value of 29.6%. Moreover, the heat release and toxic smoke emission were significantly lessened, which can be own to the adsorption of core–shell hybrid materials and the barrier effect of the P and N element crosslinked carbon layer. Herein, this work extends the idea of preparing multipurpose high-performance composites and designs and synthesizes an eco-friendly and efficient flame retardant with a double shell structure. [ABSTRACT FROM AUTHOR]

A novel and bio-based adenosine triphosphate (ATP) pillared Mg Al layered double hydroxide (LDHs-ATP) was fabricated via calcination-reconstruction, followed by the incorporation of a highly efficient flame retardant into polypropylene (PP). The XRD result indicated that the interlayer channel of LDHs-ATP was increased to 16.6 Å. Indeed, the increase of the LDHs-ATP interlayer spacing promoted the uniform dispersion and thermal stability, which were further proved by the SEM and TG-DTG results. As expected, the PP/LDHs-ATP composite reached a LOI value of 29.1% and created a UL-94 V-0 rating with only 20 wt% LDHs-ATP loading. Furthermore, CCT illustrated that the peak heat release rate (PHRR), total heat release (THR) and total smoke release (TSR) of PP/LDHs-ATP composite exhibited a series of decreases of 55.9%, 39.5% and 56.4%, respectively, compared with that of Neat PP. [Display omitted] • A bio-based ATP pillared hydrotalcite (LDHs-ATP) was successfully fabricated. • With 20 wt% LDHs-ATP, the PP/LDHs-ATP reached LOI of 29.1% and got UL-94 V 0 rating. • The improvements attributed to synergistic effect from LDHs and ATP. [ABSTRACT FROM AUTHOR]