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Abstract Co-continuous morphology in polymer blends has been well demonstrated to reduce percolation threshold and enhance electrical conductivity by selective dispersion of carbon nanotubes in one phase or at interfaces. In this work, a flexible, co-continuous, and conductive poly(ethylene-co-1-octene)/thermoplastic polyurethane/multi-walled carbon nanotube (POE/TPU/MWCNT) composite has been fabricated by controlling the dispersion of MWCNTs in the TPU phase. The interfacial interaction between the two polymers in the composites has been enhanced by using a gentle crosslinking reaction. The percolation threshold of the composites decreased from 0.43 to 0.29 vol% and electrical conductivity rose more than one order of magnitude after gentle crosslinking because of the very continuous TPU/MWCNT phase, the MWCNT fillers selective distribution, and the strong interfacial interaction between the two polymers. Furthermore, the complex viscosity, storage modulus, tensile strength, and elongation at break of the composites were improved by the gentle crosslinking reaction. For example, the composites with 0.58 vol% MWCNT fillers achieved 1.4- and 2.4-fold improvement in tensile strength and elongation at break after gentle crosslinking, respectively. In addition, the flexibility of the composites was well maintained by the gentle crosslinking reaction, resulting in excellent piezoresistive behavior of the composites. The stability and reliability of the piezoresistive response of the composites were enhanced by the gentle crosslinking reaction, owing to the stability of the MWCNT conductive network and the strong interfacial interaction. We propose that a gentle chemical crosslinking reaction between the two polymers is an alternative method for improving electrical conductivity and stabilizing the conductive network for co-continuous conductive polymer composites. Highlights • The interfacial interaction between TPU and POE was enhanced by a gentle crosslinking reaction. • The very continuous TPU/MWCNT phase was found in the crosslinking POE/TPU/MWCNT composites. • The crosslinking composites exhibited high electrical conductivity and low percolation threshold. • The stability and reliability of piezoresistive response were enhanced by the gentle crosslinking reaction. • The gentle crosslinking reaction also enhanced the mechanical properties of the composites. [ABSTRACT FROM AUTHOR]

Multi-walled carbon nanotubes (MWCNTs) are known for improving the mechanical and electrical properties of polymers. The dispersion state of MWCNTs in the polymer matrix is critical for the fabrication of high-performance nanocomposites. Here, we show a simple strategy for tuning the dispersion state of MWCNTs in poly(ε-caprolactone) (PCL) via graphene oxide (GO) nanosheets and to further balance electrical and mechanical properties of the PCL/MWCNT nanocomposites. The strong π-π interactions between MWCNTs and GO nanosheets lead to easy adsorption of MWCNTs on GO nanosheet surfaces to form GO/MWCNT hybrids that retard the aggregation of MWCNTs in PCL. Furthermore, the GO/MWCNT ratio could also affect the dispersion of GO/MWCNT hybrids in PCL. Three different dispersion states of MWCNTs were found in the PCL matrix, i.e. PCL/MWCNT, PCL/GO/MWCNT (1/4) and PCL/GO/MWCNT (2/1) nanocomposites that represented severe, low and almost no aggregation of MWCNTs, respectively. The GO/MWCNT hybrids with a 2/1 ratio showed better dispersion in PCL matrix than the hybrids with a 1/4 ratio and pristine MWCNTs. The PCL/GO/MWCNT nanocomposites with almost no aggregation of GO/MWCNT (2/1) hybrids exhibited the highest tensile strength and elongation at break in comparison to the PCL/GO/MWCNT (1/4) nanocomposites and PCL/MWCNT nanocomposites. However, the best electrical conductivity was achieved in the PCL/GO/MWCNT (1/4) nanocomposites due to the low aggregation of MWCNTs. [ABSTRACT FROM AUTHOR]

• A new strategy is developed to achieve chemically stable Ti 3 C 2 T x MXene. • Mechanical properties of IL-MXene film is significantly improved. • The mechanism for improved chemical stability of IL-MXene sheet is proposed. Ti 3 C 2 T x MXene with two-dimensional (2D)-layered structure shows potential application in various fields owing to its superb metallic conductivity and excellent solution processability. However, a fundamental challenge limiting the implementation of Ti 3 C 2 T x in practical applications is its susceptibility to oxidation in either humid or aqueous environments only within a few days, which results in the disassembly of the 2D-layered structure and severely deteriorates the functional properties including electrical conductivity, mechanical strength and EMI shielding performance. Herein, we firstly demonstrate a robust procedure to protect sensitive Ti 3 C 2 T x from degradation by modification with imidazolium-based inion liquid (IL), which remarkably improves the chemical stability of Ti 3 C 2 T x in aqueous and significantly increases the mechanical strength of assembled freestanding Ti 3 C 2 T x film (IL-MXene). The crystalline structure of IL-MXene sheet remains intact up to 30 days and preserves the 2D-layered structure as long as 8 months in aqueous, meanwhile, the tensile strength of freestanding IL-MXene film is as high as 75.9 ± 4.9 MPa and the increment is up to 84% when compared to that of untreated MXene film (41.2 ± 4.5 MPa). A novel mechanism for improved chemical stability of MXene sheet was proposed and elucidated based on the radical-scavenging ability of IL and the surface chemistry of MXene sheet. This study provides a new strategy to achieve chemically stable Ti 3 C 2 T x and improved mechanical strength of assembled MXene film, which is also available for other type of MXenes. [ABSTRACT FROM AUTHOR]

Conductive polydimethylsiloxane (PDMS) composites have attracted extensive attention worldwide due to its potential application on wearable electronics and strain sensors. In this work, silicon dioxide micro-particles (μ-SiO 2) were added into the flexible PDMS/multi-walled carbon nanotubes (MWCNT) composites to improve their electrical conductivity and piezoresistive sensitivity. First, the μ-SiO 2 particles can exhibit volume exclusion effect to dense MWCNT fillers in PDMS matrix, which leads to the high electrical conductivity and low percolation threshold. Furthermore, the larger μ-SiO 2 particles could give higher electrical conductivity and lower percolation threshold. For examples, the electrical conductivity and percolation threshold of the PDMS/MWCNT composites with 0.3 vol% MWCNT increased from 3.5 × 10−9 to 2.2 × 10−4 S/m and decreased from 0.44 to 0.08 vol%, respectively, by the incorporation of 30 vol% 85 μm-SiO 2 particles. Second, the piezoresistive sensitivity of PDMS/MWCNT composites was abruptly enhanced by the addition of μ-SiO 2 particles because of the high modulus of μ-SiO 2 particles, which resulted in the asymmetric deformation in the composites. The deformation of PDMS/MWCNT phase was higher in the PDMS/MWCNT/μ-SiO 2 composites than that of the PDMS/MWCNT composites, which leaded to high piezoresistive sensitivity. For example, the gauge factor (GF) of the PDMS/MWCNT composites increased from 1.3 to 62.9 at 30% compression strain by the addition of 30 vol% 1 μm-SiO 2 particles. The highest piezoresistive sensitivity was found in the PDMS/MWCNT/μ-SiO 2 composites with lowest size of μ-SiO 2 particles due to the highest deformation of PDMS/MWCNT phase. [ABSTRACT FROM AUTHOR]

Anisotropic conductive composites with segregated conductive networks were constructed in poly( l- lactide)/poly(ε-caprolactone)/multi-walled carbon nanotubes/nickel (PLLA/PCL/MWCNT/Ni) composites by aligning Ni particles using a low magnetic field. Firstly, MWCNTs were melt-mixed with PLLA to form PLLA/MWCNT composites and then pulverized into microscale PLLA/MWCNT particles 425–850 μm in size. Later, the Ni particles were dispersed in PCL to yield PCL/Ni composites and then mixed with PLLA/MWCNT particles at 100 °C, a temperature lying in between the melting temperatures of PCL and PLLA. The coated PLLA/MWCNT particles were compressed to form PLLA/PCL/MWCNTs/Ni composites with segregated structures. A remarkable conductive anisotropy was observed in the segregated samples after magnetic alignment in a low magnetic field of ∼47.5 mT at 100 °C for 30 min. The electrical conductivity of the segregated samples diametrically increased in the direction parallel to the magnetic field, but decreased in the direction perpendicular to the magnetic field after the magnetic alignment of Ni particles in the PCL phase. Electrical conductivity in the parallel direction was almost eight orders of magnitude higher than that in the perpendicular direction at 3.0 wt% Ni and 0.7 wt% MWCNTs. Conductive anisotropy in the segregated systems could also be easily regulated by controlling the treatment time or changing the direction of the magnetic field. However, electrical conductivity could be maintained in both vertical and parallel directions in conventional composites after magnetic treatment because Ni particles preferably dispersed in the continuous PLLA phase, in which the Ni particles cannot be aligned at 100 °C. In addition, these segregated samples with alignment of Ni particles also exhibited the mechanical enhancement and high-performance electromagnetic interference shielding. [ABSTRACT FROM AUTHOR]

A novel strategy for confined synthesis of graphene wrapped nano-sized LiMn 0.5 Fe 0.5 PO 4 hybrid composite has been developed, including co-precipitation and solvothermal reactions. The LiMn 0.5 Fe 0.5 PO 4 nanoparticles with a constrained diameter of 20 nm are homogeneously wrapped by a continuous interconnected graphene sheets. The mechanism and composite structure evolution during the process are carefully investigated and discussed. With the shortened Li + diffusion paths and enhanced electron conductivity, the hybrid composite shows high discharge capacity and superior rate performance with the discharge capacities of 166 mA h g −1 at 0.1 C and 90 mA h g −1 at 20 C. Excellent cycle stability is also demonstrated with only about 7.8% capacity decay after 500 cycles at 1 C. [ABSTRACT FROM AUTHOR]

Single-walled carbon nanotubes (SWCNTs) are ideal candidates for transparent conductive films (TCFs) due to their excellent optical transparency and electrical conductivity. The geometry of SWCNTs, including the tube diameter, bundle length and bundle diameter, is vital to high-performance TCFs. Herein, we synthesized SWCNTs by floating catalyst chemical vapor deposition (FCCVD). The SWCNT geometries were tuned by hydrogen (H 2), and we found that the tube diameter, bundle length and bundle diameter increase with the H 2 concentration. Besides, we observed the formation of SWCNT loop at the tube ends. Both the number and circumference of loops increased with the increment of bundle length. Further, the loops were also found to affect the conductivity of SWCNT thin film. Excessive number of loops with large size could reduce the conductivity of SWCNT thin film. At the optimized H 2 concentration, we obtained the SWCNT TCF with sheet resistances of 290 and 95 Ω/sq. for the pristine and AuCl 3 doped SWCNT films, respectively, at 90% transmittance. Our work demonstrates the importance of H 2 for SWCNT synthesis and the critical role of loops on film conductivity, blazing new ideas for future research to obtain SWCNT TCFs with improved performance. [Display omitted] • The geometry of SWCNT (i.e. tube diameter and length) is controlled by H 2. • As the length of SWCNT increases, the number and size of SWCNT loops increase. • The large proportion of the loops in SWCNT reduces the conductivity of TCFs. [ABSTRACT FROM AUTHOR]

Exploring high-efficiency and low-cost electrocatalysts with outstanding durableness for oxygen evolution reaction (OER) is the key to practical production of eco-friendly hydrogen energy by water electrolysis technology, which remains challenging. In this paper, the tremella-like MnO 2 /(Fe,Ni) 3 S 4 hybrid nanostructures are supported on nickel foam matrix by a facile and governable method, with predominant OER properties in 1.0 M KOH solution. Profiting from the synergistic effect between MnO 2 and (Fe,Ni) 3 S 4 , this optimal MnO 2 /(Fe,Ni) 3 S 4 catalyst only requires 220 and 325 mV to fulfill current densities of 10 and 500 mA cm−2, respectively. Through the inheritance and optimization of MnO 2 and (Fe,Ni) 3 S 4 nanostructures, this hybrid catalyst possesses a large specific surface area, appropriate exposure active site and favorable electrical conductivity. Besides, the self-supported MnO 2 /(Fe,Ni) 3 S 4 electrode exhibits eminent stability at 10 and 100 mA cm−2 during the 20 h OER process. • 1.The tremella-like nanostructure provides plentiful active sites. • 2.Vast openings are beneficial to the conversion of water molecules. • 3.MnO 2 and (Fe,Ni) 3 S 4 form hybrid nanostructures. • 4.This unique hybrid material has a good synergistic effect. • 5.This electrocatalyst exhibits excellent OER activity and stability. [ABSTRACT FROM AUTHOR]

• α-MnSe Nanosheets are prepared via a facile hydrothermal method. • The effect of reaction time on electrochemical performance is investigated. • The α-MnSe electrode delivers a high capacity of 88.3 mAh g−1 at 1 A g−1. • The asymmetric supercapacitor exhibits a high energy density of 39.3 Wh kg−1. Transition metal selenides are regarded as emerging materials for energy storage devices because of their good electrical conductivity and electrochemical activity. Here, a binder-free ultrathin α-MnSe nanosheets electrode is prepared and the supercapacitor performance is comprehensively explored. Due to the increased active sites, enlarged contact area for electrolyte, as well as shorten ions diffusion pathway, the prepared electrode delivers high capacity of 88.3 mAh g−1 at 1 A g−1, good rate capability, and long-term durability (91% remain after 5000 cycles). Moreover, the asymmetric supercapacitor, fabricated by α-MnSe anode and active carbon cathode, displays a high energy density of 39.3 Wh kg−1 at a power density of 0.92 kW kg−1 and satisfying cycle performance. This study demonstrates that the binder-free α-MnSe electrode holds great promise for supercapacitor. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel strategy was proposed to achieve flexible liquid metal/cellulose nanofiber film. • The film exhibits excellent structural stability and EMI shielding effectiveness of ~ 65 dB. • Simulation in the frequency domain was introduced to investigate the shielding mechanism. Liquid metal (LM) is a promising candidate for electromagnetic interference (EMI) shielding due to the superb electrical conductivity and easy processing. However, poor compatibility caused by high surface tension, insulated oxide shells formed during processing, and unmanageable fluidity at elevated temperature of LM severely hinder its application in the field of EMI shielding. Herein, we develop a novel processing strategy integrating ball-milling dispersion, freeze-drying and compression molding to achieve free-standing and flexible LM/cellulose nanofiber composites (LM/CNF) film, in which the oxide shells of LM droplets generated by ball-milling are broken by mechanical compression, and LM droplets are coalesced while confined by CNF to construct a continuously conductive path. As a result, the robust LM/CNF film shows tensile strength of above 30 MPa, and it possesses electrical conductivity of 96,000 S/m, leading to remarkable shielding effectiveness (SE) of above 65 dB with a thickness of only 300 µm in a broad frequency range of 4–18 GHz covering C-band, X-band and Ku-band. Moreover, LM/CNF film exhibits excellent structural stability and EMI shielding performance reliability after high-temperature treatment. Besides, simulation in the frequency domain with ANSYS HFSS 2019 R2 is performed to intuitively understand the shielding mechanism of LM/CNF film. It is found that the attenuation of electromagnetic waves is mainly based on reflection. This study proposes a fresh scenario to achieve high-performance EMI shielding material and paves the way for potential applications of LM in portable and wearable smart electronics. [ABSTRACT FROM AUTHOR]

High-quality F-doped graphene as rate capability anode for Li-ion battery is prepared by a one-step arc-discharge method. The in-situ formation of LiF nano-particles in the first lithium insertion process enhance the interlayer spacing of graphene, thus provid enough void for rapid ion diffusion, which is capable to deliver much high reversible capacity, outstanding rate performance, and excellent cycling stability. • A high-quality F-modified graphene as rate capability anode for Li-ion battery is reported. • The structural evolution of F-modified graphene electrode during the Li+ insertion/extraction is investigated. • The F-modified graphene delivers a high reversible capacity, outstanding rate performance, and excellent cycling stability. The application of lithium ion battery (LIB) in portable electronics and electric vehicle has received tremendous attention, however, challenges remain in seeking suitable high-capacity anode materials with excellent rate performance and thus potentially to boost the energy/power density. Here we report an arc-discharge production of high-quality F-modified graphene as anode for LIB with high-rate capability. As a result of F-modified, the acquired graphene exhibits high atomic ratio of C/O, excellent electric conductivity and more crumpled and wrinkled surface. Interestingly, the in-situ formation of LiF nanoparticles during the first Li+ insertion process not only act as barriers to effectively prevent the agglomeration and re-stacking of graphene sheets but also enhance the interlayer spacing, thus providing enough void for rapid Li+ ion insertion/extraction. These optimized features enable the resultant F-modified graphene delivers a high reversible capacity (783.2 mAh g−1 at 100 mA g−1), outstanding rate performance (298.5 mAh g−1 at 10 A g−1), and excellent cycling stability (>91% capacity retention after 1000 cycles), providing great application prospect in high-enegy-power LIB. [ABSTRACT FROM AUTHOR]