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Silicon (Si) as the anode material for lithium-ion batteries (LIBs) has attracted much attention due to its high theoretical specific capacity (4200 mAh/g). However, the specific capacity and cycle stability of the LIBs are reduced due to the pulverization caused by the expansion of Si coated on Cu (copper) foil during cycles. In order to solve this problem, researchers have used an ultra-thin Si deposition layer as the electrode, which improves cyclic stability and obtains high initial coulomb efficiency of LIBs. However, suitable substrate selection is crucial to fabricate an ultrathin Si deposition layer electrode with excellent performance, and a substrate with a three-dimensional porous structure is desirable to ensure the deposition of an ultrathin Si layer on the whole surface of the substrate. In this paper, the Si thin layer has been deposited on a binder-free hybrid film of carbon nanotubes (CNTs) and carbon nanocoils (CNCs) by magnetron sputtering. Compared with densely packed CNT film and flat Cu foil, the loose and porous film provides a large surface area and space for Si deposition, and Si can be deposited not only on the surface but also in the interior part of the film. The film provides a large number of channels for the diffusion and transmission of Li+, resulting in the rapid diffusion rate of Li+, which improves the effective lithium storage utilization of Si. Furthermore, the CNC itself is super elastic, and film provides an elastic skeleton for the Si deposition layer, which eases its volume expansion during charge and discharge processes. Electrochemical tests have showed that the Si/CNT–CNC film electrode has excellent performance as anode for LIBs. After 200 cycles, the Si/CNT–CNC film electrode still had possessed a specific capacity of 2500 mAh/g, a capacity retention of 92.8% and a coulomb efficiency of 99%. This paper provides an effective way to fabricate high performance Si-nanocarbon composite electrodes for LIBs. [ABSTRACT FROM AUTHOR]

[Display omitted] • A biomass-derived hydrogel solar evaporator is constructed by PVA, SLS and CNT. • Evaporator shows an evaporation rate of 2.09 kg m−2 h−1 under 1 Sun illumination. • Evaporator can precisely adjust the type of water and reduce the vapor enthalpy. • The remarkable antibacterial performance is realized by the addition of SLS. • It shows high performance in outdoor solar desalination to produce freshwater. Hydrogel has been regarded as one of the most promising candidates for next-generation solar evaporation technology to produce freshwater from non-potable water. However, synthesizing hydrogel absorbers that can precisely regulate water state and significantly reduce the water vaporization enthalpy remains a grand challenge. Herein, we report the rational design of a novel hydrogel hybrid solar evaporator constructed by poly(vinyl alcohol) and sodium lignosulfonate (SLS), with addition of carbon nanotube as a light absorption material. The abundant sulfonate and hydroxyl groups of SLS enhance the interplay between hydrogel and water molecule through electrostatic interaction and hydrogen bond. As such, the presence of SLS not only remarkably promotes the hydrophilicity and water transport of hydrogel, but also precisely tunes the state of water molecule and the content of intermediate water for reducing the water vaporization enthalpy. The combined advantageous features endow the as-prepared hydrogel with an evaporation rate up to 2.09 kg m−2 h−1 under 1 Sun illumination, along with good anti-acid/basic abilities, antibacterial property, high salt-tolerance, and self-cleaning capability in purifying different types of wastewater. Finally, an outdoor solar seawater desalination device is designed to generate drinking water from seawater. The daily drinking water production amount per square meter is ca. 13 kg, which satifies the five adults' daily water consumption (12.5 kg). The present study highlights that rationally constructing the molecular architecture of hydrogel and tuning the interplay between water and hydrogel are effective strategies to fabricate advanced hydrogel solar evaporators for addressing the global freshwater shortage. [ABSTRACT FROM AUTHOR]

• A hybrid model of Li-O 2 battery is developed with the morphological evolution of the cathode pore structure. • Mechanisms of discharge failure under different conditions are revealed. • Evolution of the cathode pore structure morphology needs to be considered for the cathode made of small-sized CNP or CNT. A comprehensive model for lithium-oxygen (Li-O 2) batteries is proposed and the discharge performance across varying cathode thickness, porosity, and pore structural evolution modes is thoroughly investigated. The results reveal that the cathode surface passivation restricts the discharge capacity but promotes the uniform distribution of lithium peroxide (Li 2 O 2), especially near the O 2 side. The electrode thickness of 255 μm serves as the boundary point between the two limiting mechanisms, with thicker electrodes primarily governed by O 2 diffusion and thinner ones by surface passivation. In addition, a novel hybrid model is proposed with the morphological change of the cathode pore structure, which can predict the discharge performance made of different carbon materials, proving its superiority over the commonly used Single model. The maximum discharge capacities of carbon nanoparticle (CNP)- and carbon nanotube (CNT)-based cathodes are obtained at the radius of CNP and CNT of 30 nm and 20 nm, respectively. The superiority of discharge performance of the CNP-based cathode over the CNT-based cathodes becomes more pronounced as the carbon material radius increases. The evolution of the cathode pore structure morphology needs to be considered for the cathode made of small-sized CNP or CNT, such as r CNP = 10 nm and r CNT = 20 nm. [ABSTRACT FROM AUTHOR]

Abstract: Amorphous RuO2·xH2O was well coated on the benzenesulfonic functionalized multi-wall carbon nanotubes (f-MWCNTs) successfully via hydrothermal method. The decorated benzenesulfonic groups served as a bifunctional role both for solubilizing and dispersing MWCNTs into aqueous solution and for tethering Ru3+ precursor to facilitate the following uniform chemical deposition of RuO2·xH2O. The electrochemical performance of RuO2/f-MWCNTs and utilization of RuO2·xH2O were evidenced by cyclic voltammetry and galvanostatic charge/discharge tests. The specific capacitance of 1143Fg−1 for RuO2·xH2O was obtained from RuO2/f-MWCNTs with 32wt.% RuO2·xH2O, which was much higher than that of just 798Fg−1 for the RuO2/p-MWCNTs. Even though the RuO2·xH2O loading increases to 45wt.%, the utilization of RuO2·xH2O still possesses as high as 844.4Fg−1, indicating a good energy capacity in the case of high loading. [Copyright &y& Elsevier]

Abstract: Iron-filled nitrogen-doped carbon (Fe@CNx) nanotubes were prepared by an in situ chemical vapor deposition with ferrocene as catalyst and ethylenediamine as carbon and nitrogen sources. The as-grown products were characterized using an X-ray diffractometer, transmission electron microscope, X-ray photoelectron spectroscopy, thermogravimetric analyzer and vibrating sample magnetometer. It was found that the “bamboo-like” N-doped carbon nanotubes were filled with 41.1wt% of Fe nanoparticles. The coercivity and saturation magnetization of Fe@CNx nanotubes were much larger than those of carbon nanotubes and CNx nanotubes. [Copyright &y& Elsevier]

The applications of poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) in tissue engineering have been widely studied. This study aimed to compare the biocompatibility and osteoinductivity of single-walled carbon nanotubes (SWCNTs)/PHBV composites with multi-walled CNTs (MWCNTs)/PHBV composites. CNTs were dispersed in PHBV by ultrasonication and composites were created using thermal injection moulding. In order to test their biocompatibility and osteoinductivity. Rat osteoblasts (rOBs) were then cultured and seeded on the composites. The composites were implanted in rat femoral bone defects. Our results showed that lower weight percentages of SWCNTs and MWCNTs (2-4%) improved both their mechanical and thermal decomposition properties. However, further reduction of rOBs cell death was observed in MWCNTs/PHBV. SWCNTs were shown to upregulate the expression of Runx-2 and Bmp-2 in early stage significantly, while MWCNTs showed a stronger long-term effect on Opn and Ocn. The in vivo result was that MWCNTs/PHBV composites induced intact rounding new bone, increased integration with new bone, and earlier completed bone remodeling when compared with SWCNTs. Immunohistochemistry also detected higher expression of RUNX-2 around MWCNTs/PHBV composites. In conclusion, there were no differences observed between SWCNTs and MWCNTs in the reinforcement of PHBV, while MWCNTs/PHBV composites showed better biocompatibility and osteoinductivity both in vitro and in vivo. [ABSTRACT FROM AUTHOR]

To improve the sluggish kinetics of oxygen reduction reaction (ORR) is critically important for the development of fuel cells. It is generally recognized that catalysts with multi-transfer channels and varied active sites can energetically facilitate the ORR-relevant species transfer to improve the oxygen reduction rate. In this study, N-doped carbon nanotubes-crossed MoS 2 /carbon (N-MoS 2 /CNTs/C) catalysts are synthesized at temperatures of 600–900 °C using an in-situ reduction self-assembly method. In both acid (0.5 M H 2 SO 4 ) and alkaline (0.1 M KOH) media, N-MoS 2 /CNTs/C (800 °C) catalyst exhibits a promising ORR activity and favors a four-electron reduction pathway. The highly-maintained tubular CNTs in N-MoS 2 /CNTs/C (800 °C) can supply the multidimensional pathways for transferring the ORR-relevant species. N atoms doping can not only increase the structural defects of MoS 2 lattice (Mo–N x ) to expose more Mo–S x sites, but also induce various N functional groups into the carbon matrix (CNTs and porous carbon), which are favorable to improve the activation, adsorption and reduction of oxygen. Therefore, the distinct structures endow the N-MoS 2 /CNTs/C catalysts with high activity towards ORR. Furthermore, the N-MoS 2 /CNTs/C (800 °C) also exhibits a promising ORR activity in neutral medium (microbial fuel cells (MFCs)). MFCs with the N-MoS 2 /CNTs/C (800 °C) cathode exhibits the maximum power density of 987.4 mW m −2 , which is much higher than that of commercial Pt/C (601.96 mW m −2 ). These results indicate that N-MoS 2 /CNTs/C catalysts can be considered as a promising alternative to Pt/C for ORR. [ABSTRACT FROM AUTHOR]

[Display omitted] • A film composed of carbon nanotube-carbon nanocoil (CNT-CNC) mixture was prepared using a simple vacuum filtration method. • The unique structure makes the CNT-CNC film fully and tightly contact the active materials and electrolyte. • The lithium-ion batteries using CNT-CNC film as current collector show high capacity and excellent cycling performances. Lithium-ion batteries (LIBs) have attracted extensive attention in many fields but are still limited in application by capacity loss under long cycles. The poor contact between the current collector (CC) and active materials is one of the reasons that cause the energy attenuation of LIBs during long-term use. Herein, hybrid films constructed by mixing carbon nanotubes (CNTs) and carbon nanocoils (CNCs) through a simple vacuum filtration method are used as CCs for LIBs. It is found that the LIB using the film with a mass ratio of CNTs: CNCs = 3:1 shows the best performance, exhibiting a high capacity of 135.7 mAh g−1 at 5C, and stable cycling performance (>99% capacity retention) after 500 charge/discharge cycles at 1C. The excellent contact of active materials with the CNT-CNC hybrid film is achieved by the well-constructed CNC skeleton, making the CNTs more dispersed to form a uniform and interconnected structure. This work certifies that the CNT-CNC hybrid films are a promising candidate as CCs for high-performance LIBs. [ABSTRACT FROM AUTHOR]

Abstract: In the present work, graphene/polypyrrole/carbon nanotube (GN/PPy/CNT) ternary composites have been fabricated via in situ polymerization method. The negatively charged poly(sodium 4-styrene sulfonate) is used for dispersing GN and CNT in aqueous phase and tethering pyrrole monomer to facilitate the formation of uniform PPy coating. Morphology analysis shows that the stacking of laminated PPy/GN composite is inhibited by introducing one-dimensional CNT to form GN/PPy/CNT composite with three-dimensional hierarchical structure. The prepared GN/PPy/CNT composite with GN:CNT=8:1 (8GCPPy) exhibits a large surface area of 112m2 g−1 and meso- and macro-porosity system, which favor the diffusion of the electrolyte ions into the inner region of electrode. The supercapacitive behaviors of the sample electrodes are evaluated with cyclic voltammetry and galvanostatic charge/discharge measurements in 1M KCl electrolyte. The specific capacitance of 8GCPPy at a current density of 0.2Ag−1 (361Fg−1) is much higher than that of pure PPy (176Fg−1) and binary composites of CNT/PPy (253Fg−1) and GN/PPy (265Fg−1). In addition, owing to the GN and CNT synergistic releasing the intrinsic differential strain of PPy chains during charge/discharge processes, the 8GCPPy composite also shows stable cycling performance (4% capacity loss after 2000 cycles). [Copyright &y& Elsevier]

Abstract: The flexible electrodes have important potential applications in energy storage of portable electronic devices for their powerful structural properties. In this work, unique flexible films with polypyrrole/carbon nanotube (PPy/CNT) composite homogeneously distributed between graphene (GN) sheets are successfully prepared by flow-assembly of the mixture dispersion of GN and PPy/CNT. In such layered structure, the coaxial PPy/CNT nanocables can not only enlarge the space between GN sheets but also provide pseudo-capacitance to enhance the total capacitance of electrodes. According to the galvanostatic charge/discharge analysis, the mass and volume specific capacitances of GN-PPy/CNT (52wt% PPy/CNT) are 211Fg−1 and 122Fcm−3 at a current density of 0.2Ag−1, higher than those of the GN film (73Fg−1 and 79Fcm−3) and PPy/CNT (164Fg−1 and 67Fcm−3). Significantly, the GN-PPy/CNT electrode shows excellent cycling stability (5% capacity loss after 5000 cycles) due to the flexible GN layer and the rigid CNT core synergistical releasing the intrinsic differential strain of PPy chains during long-term charge/discharge cycles. [Copyright &y& Elsevier]

Abstract: A film composed of graphene (GN) sheets, polyaniline (PANI) and carbon nanotubes (CNTs) has been fabricated by reducing a graphite oxide (GO)/PANI/CNT precursor prepared by flow-directed assembly from a complex dispersion of GO and PANI/CNT, followed by reoxidation and redoping of the reduced PANI in the composite to restore the conducting PANI structure. Scanning electron microscope images indicate that the ternary composite film is a layered structure with coaxial PANI/CNT nanocables uniformly sandwiched between the GN sheets. Such novel hierarchical structure with high electrical conductivity perfectly facilitates contact between electrolyte ions and PANI for faradaic energy storage and efficiently utilizes the double-layer capacitance at the electrode–electrolyte interfaces. The specific capacitance of the GN/PANI/CNT estimated by galvanostatic charge/discharge measurement is 569Fg−1 (or 188Fcm−3 for volumetric capacitance) at a current density of 0.1Ag−1. In addition, the GN/PANI/CNT exhibits good rate capability (60% capacity retention at 10Ag−1) and superior cycling stability (4% fade after 5000 continuous charge/discharge cycles). [Copyright &y& Elsevier]

Abstract: A flexible graphene/multiwalled carbon nanotube (GN/MWCNT) film has been fabricated by flow-directed assembly from a complex dispersion of graphite oxide (GO) and pristine MWCNTs followed by the use of gas-based hydrazine to reduce the GO into GN sheets. The GN/MWCNT (16wt.% MWCNTs) film characterized by Fourier transformation infrared spectra, X-ray diffraction and scanning electron microscope has a layered structure with MWCNTs uniformly sandwiched between the GN sheets. The MWCNTs in the obtained composite film not only efficiently increase the basal spacing but also bridge the defects for electron transfer between GN sheets, increasing electrolyte/electrode contact area and facilitating transportation of electrolyte ion and electron into the inner region of electrode. Electrochemical data demonstrate that the GN/MWCNT film possesses a specific capacitance of 265Fg−1 at 0.1Ag−1 and a good rate capability (49% capacity retention at 50Ag−1), and displays an excellent specific capacitance retention of 97% after 2000 continuous charge/discharge cycles. The results of electrochemical measurements indicate that the freestanding GN/MWCNT film has a potential application in flexible energy storage devices. [Copyright &y& Elsevier]

Abstract: A novel and facile non-covalent process was applied to sulfonate multiwalled carbon nanotubes (MWCNTs) with a high –SO3H loading carbonaceous (C-SO3H). Then the sulfonated multi-walled carbon nanotubes/polypyrrole nanocomposite (MWCNTs/C-SO3H/PPy) was synthesized by the in situ chemical polymerization of pyrrole on the non-covalent sulfonated MWCNTs (MWCNTs/C-SO3H) using ammonium persulfate as oxidant at low-temperature. Fourier transform infrared (FT-IR) spectra confirm the modification of MWCNTs and an existence of interaction between the –SO3H group of the modified MWCNTs and the N–H group of PPy. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), FT-IR and ultraviolet–visible (UV–vis) spectra show that uniform PPy layer coated on the sidewall of MWCNTs/C-SO3H. The electrochemical properties of the MWCNTs/C-SO3H/PPy composite were studied by cyclic voltammetry and galvanostatic charge/discharge test. The composite possesses good rate response and stable specific capacitance, the specific capacitance loss is only 3% even after the 1000 cycles. [Copyright &y& Elsevier]