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Recent years witness the rapid development of the internet of things and artificial intelligence, which ignites the worldwide research needs for flexible electronics to fulfill intelligent human–machine interfaces. As a promising future technology, the flexible epidermal electrode attracts great research enthusiasm in the field of intelligent robots, human–machine interfaces, virtual and augmented reality, medical treatment, health monitoring, and other emerging applications. However, it is still the main challenge to enhance the vertical charge conduction bridging the interface of metal electrode and human skin, which constructs an insurmountable obstacle for wide usage. In this article, a low-cost embossing fabrication is introduced to pattern a stretchable epidermal electrode device that consists of a carbon-nanotube (CNT)-composed metal thin film. Benefited from the excellent flexibility and stretchability, the fabricated electrode can conformably attach to the skin and collect high-quality bioelectrical signals. Moreover, this epidermal electrode features good conductivity along the vertical path for acquiring the epidermal charge, due to conductive CNTs bridging the interface of skin and this epidermal electrode. With this device structure configuration, the impedance between skin and epidermal electrode could effectively reduce by more than 50%. The conformal contact mechanism relies upon an ultra-thin metal film on skin texture, which makes the device achieves high sensitivity and durability in a human–machine interface. The electrocardiogram (ECG) and electromyography (EMG) demonstration and gesture recognition further conclude that this technology has a chance to bring up the potential of clinical applications as a human–machine interface. [ABSTRACT FROM AUTHOR]

Iron molybdate (FeMoO 4) nanostructures show great promise as a superior anode for sodium-ion batteries. However, its use in practical application is hampered by its poor electronic conductivity, large volume changes and sluggish reaction kinetics. Herein, we have developed an interconnected network of multiwall carbon nanotube (CNT) and FeMoO 4 (FMO) by a simple one-step hydrothermal method. As well as providing efficient channels for charge transfer and diffusion, highly conductive CNTs also have a degree of volume elasticity and excellent electrical conductivity to ensure migration of sodium ions, enabling both fast kinetics and long-term stability. As a result, the FMO@CNT anode delivers a high reversible capacity of 485 mA h g−1 at 0.05 A/g and very long cycling stability with a capacity of 75 mA h g−1 after 1000 cycles at 1 A/g. Furthermore, by combining the ex-situ X-ray diffraction, ex situ X-ray photoelectron spectroscopy and cyclic voltammetry results, sodium ion storage mechanism of the FMO@CNT electrode obeys a conversion mechanism. The results of this work provide a better understanding on the sodium ion storage mechanism of binary metal oxides. [ABSTRACT FROM AUTHOR]

Single‐walled carbon nanotube (SWNT) horizontal arrays with specific chirality can be enriched using solid carbide catalysts on substrates. However, scale‐up production by continuous loading of the solid catalysts onto the substrates is challenging. Described here is the preparation of a floating carbide solid catalyst (FSC) for the controlled growth of SWNTs. The FSC, titanium carbide (TiC) nanoparticle, was directly obtained in the carrier gas phase by decomposition and carbonization of the titanocene dichloride precursor at high temperature. By using the TiC nanoparticle FSC, both SWNT horizontal arrays and randomly distributed networks can be obtained. The chirality of the as‐grown SWNTs were thermodynamically controlled to have fourfold symmetry. Further optimization of growth condition resulted in an abundance of (16,8) tubes with about a 74 % content. This FSC chemical vapor deposition (FSCCVD) method has potential for realizing mass growth of SWNTs with controlled structures. [ABSTRACT FROM AUTHOR]

Even though transition‐metal phosphides (TMPs) have been developed as promising alternatives to Pt catalyst for the hydrogen evolution reaction (HER), further improvement of their performance requires fine regulation of the TMP sites related to their specific electronic structure. Herein, for the first time, boron (B)‐modulated electrocatalytic characteristics in CoP anchored on the carbon nanotubes (B‐CoP/CNT) with impressive HER activities over a wide pH range are reported. The HER performance surpasses commercial Pt/C in both neutral and alkaline media at large current density (>100 mA cm−2). A combined experimental and theoretical study identified that the B dopant could reform the local electronic configuration and atomic arrangement of bonded Co and adjacent P atoms, enhance the electrons' delocalization capacity of Co atoms for high electrical conductivity, and optimize the free energy of H adsorption and H2 desorption on the active sites for better HER kinetics. [ABSTRACT FROM AUTHOR]

In this work, nitrogen-doped hollow carbon spheres (NCs) were prepared by a silica template method using dopamine as a carbon precursor. The as-prepared NCs were used to fabricate a catechol (CC) electrochemical sensor. Nitrogen doping significantly enhances the conductivity of the electrode. Therefore, NCs were successfully used to modify screen-printed electrodes, which exhibited excellent sensing performance. Under the optimized conditions, the prepared electrochemical sensor could linearly detect CC between 0.5 and 300 μM with a low detection limit of 0.14 μM. [ABSTRACT FROM AUTHOR]

The electronic structures and field emission properties of capped CNT55 systems with or without alkali metal atom adsorption were systematically investigated by density functional theory calculation. The results indicate that the adsorption of alkali metal on the center site of a CNT tip is energetically favorable. In addition, the adsorption energies increase with the introduction of the electric field. The excessive negative charges on CNT tips make electron emittance much easier and result in a decrease in work function. Furthermore, the inducing effect by positively charged alkali metal atoms can be reasonably considered as the dominant reason for the improvement in field emission properties. [ABSTRACT FROM AUTHOR]

Rational microstructure design of carbon based composites is becoming a promising method to reinforce their electromagnetic (EM) wave absorption performance, but their synthesis remains a challenge. Herein, we have reported a design of small-size Ni 2 P grown on carbon nanotubes (CNTs) as lightweight and high efficiency EM wave absorber. The Ni 2 P NPs can be uniformly grown on CNTs by controlling the nucleation and growth rate of Ni 2 P during the synthesis. The size and coverage of Ni 2 P on CNTs can be tuned by adjusting the reaction conditions with a high yield, which is large favorable for adjusting their application performance. The Ni 2 P/CNTs sample with low filler loading (30 wt%) in the paraffin wax exhibits a good wave absorption performance with the minimum reflection loss (RL mini) value of −51.8 dB at 5.28 GHz. Moreover, it shows a good EM wave absorption ability even at the thinnest thickness of 2 mm (−46.1 dB), and an effective absorption bandwidth of 11.68 GHz is achieved when the absorber thickness is in the range of 1.5–5 mm. The excellent EM wave absorbing performance makes the Ni 2 P/CNTs as a promising new microwave absorbing material in sustainable filed. The small-sized Ni 2 P coated on carbon nanotubes were designed in high yields, which can be used as enhanced lightweight electromagnetic wave absorbers with the RL mini value of – 51.8 dB at 5.28 GHz. Image 1 [ABSTRACT FROM AUTHOR]

Designing efficient, stable, and inexpensive catalysts for water splitting was critical for efficient, sustainable energy conversion. Here, a one-pot hot-colloidal route was adopted to synthesize the mono-dispersed NiCoP catalyst with a particle size of∼5.0 nm. To further improve the structural stability and electronic conductivity of the catalysts, carbon nanotubes (CNTs) were introduced. The theoretical calculations suggested that a synergistic effect between Ni and Co in the NiCoP catalyst not only leads to an obvious charge redistribution but also facilitates the electron transfer from the surface to the reactant intermediates, being responsible for the optimal ΔG H* of the catalyst. As a result, NiCoP/CNTs exhibited good HER performance both in acidic and alkaline electrolytes. The overpotentials under alkaline and acidic electrolytes were 110 mV and114 mV at a current density of 10 mA cm−2, respectively. In comparison with pristine Ni 2 P(Co 2 P), the overpotential of NiCoP/CNTs in acidic and alkaline electrolytes was reduced by 50(24) and 62(30) mV at the current density of 10 mA cm−2. Even at the current densities of 50 and 200 mA cm−2, NiCoP/CNTs still retains a much lower overpotential than other samples. Our results revealed the important roles of the synergistic effect between the transition metals and the interaction between CNTs and the phosphides, which provides some useful information for the design and optimization of relevant HER catalysts. • Synergistic interaction between Ni and Co in NiCoP/CNTs leads to charge redistribution favoring electron transfer. • CNTs can improve the conductivity of the material, reduce the interfacial impedance and increase specific surface area. • CNTs facilitate anchoring and uniform distribution of catalyst particles. [ABSTRACT FROM AUTHOR]

The controllable construction of Fe,N co-doped carbon (Fe-N-C) nanocomposite has highly potential in replacing the noble metal catalysts. Herein, the Fe/N/P-tridoped expanded carbon nanotubes (P-Fe-N-CNTs) are prepared according to a simple one-step pyrolysis procedure. The unexpanded Fe-N-C carbon nanotubes (Fe u -N-CNTs) are also fabricated for comparision. The expanded P-Fe-N-CNTs yields a high half-wave potential (E 1/2) of 0.8843 V compared with unexpanded Fe u -N-CNT and commercial Pt/C. Furthermore, the expanded P-Fe-N-CNT as catalyst of Zn-air battery achieves high electrocatalytic performance, which is better than commercial Pt/C material. The unique architecture of expanded P-Fe-N-CNTs can improve the specific surface area and promote the formation the abundant active site, thus promoting the ORR kinetic process. Density functional theory (DFT) calculations futher confirm that suitable P doping can regulate the electronic structures of the active catalytic sites. The work provides a controllable way to prepare rational expanded P-Fe-N-CNTs for different applications, especially in Zn-air battery. [Display omitted] • The morphology of Fe/N/P-tridoped expanded carbon nanotubes are firstly regulated. • The suitable P dopant can optimize the electronic structures of active sites. • The expanded P-Fe-N-CNTs promotes the formation of abundant active site. • The P-Fe-N-CNTs catalyst shows high ORR performance. • The rational expanded P-Fe-N-CNTs exhibits a potential application prospect. [ABSTRACT FROM AUTHOR]

NiCo 2 S 4 as a promising anode material for sodium ion batteries (SIBs) with rich redox potential and high theoretical specific capacity, but suffers the poor conductivity and severe volume expansion. The electrode materials with a three-dimensional (3D) framework can facilitate the migration of ions/electrons, enhance structural stability, and alleviate the volume expansion during charging/discharging. Herein, we report the NiCo 2 S 4 nanoparticles anchored on a 3D interpenetrating framework consisting of graphene nanosheets (GNs) and carbon nanotubes (CNTs) to solve the above issues. Benefiting from the structural stability and superior conductivity in special 3D structure, the as-prepared NCS@GNs@CNTs electrode delivers a high initial discharge/charge capacity (558.1/538.8 mAh g1 at 100 mA g−1), superior cyclic stability (362.8 mAh g−1 after 100 cycles at 200 mA g−1) and an excellent rate capability (311.8 mAh g−1 at 5000 mA g−1). Furthermore, the sodium-ion full-cell Na 3 V 2 (PO 4) 3 @C-NCS@GNs@CNTs test demonstrates that NCS@GNs@CNTs exhibits good cycling stability and further illustrates the possibility in practical applications. [Display omitted] [ABSTRACT FROM AUTHOR]

A simple one-pot hydrothermal method to synthesize MoO 2 /CNTs nanocomposites on nickel foam substrate for supercapacitor electrode was developed. Compared to pure MoO 2 nanoparticles, the MoO 2 /CNTs nanocomposites show better electrochemical performance. The specific capacitance values of pristine MoO 2 , MoO 2 /CNTs (5 wt%) composite and MoO 2 /CNTs (10 wt%) composite were 327.4, 467.4 F g −1 and 424.7 F g −1 of at a current density of 1 A g −1 , respectively. Especially, MoO 2 /CNTs (5 wt%) composite exhibits good rate capability and excellent cycle densities, remaining at 92.8% of the initial specific capacitance value even after 3000 cycles at 5 A g −1 . The enhanced electrochemical behaviors are mainly due to the synergistic effect of combining MoO 2 nanoparticles and CNTs. MoO 2 nanoparticles can provide higher specific capacitance, while CNTs improve the electrical conductivity and structural stability of the composite. Such nanocomposite with high performance may be used as a promising material for electrochemical supercapacitor. [ABSTRACT FROM AUTHOR]

Lithium-sulfur (Li-S) batteries appear to be one of the most promising energy-storage devices owing to the unparalleled theoretical specific energy, relatively inexpensive price and abundant resources. Despite these attractive features, the practical performances of sulfur cathode still remain a lot of challenges, such as the electrical insulating nature of S and Li 2 S, huge volume change during cycling, notorious shuttle effect of lithium polysulfide intermediates (LiPSs), sluggish redox kinetics and construction of thick electrodes with high sulfur loading. Here, CoFe 2 O 4 nanoparticles anchored on the carbon nanotube (CNT) paper is proposed as free-standing sulfur host to address the issues. The cross-linking CNT network can serve as conductive matrix and accommodate volume change upon cycling simultaneously. Meanwhile, the CoFe 2 O 4 nanoparticles are capable of effectively anchoring LiPSs to suppress the shuttle effect and accelerating LiPSs conversion to boost redox kinetics. Moreover, the free-standing paper electrode without any binder is conducive to constructing stable cathode with high sulfur loading. In consequence, the well-designed S/CoFe 2 O 4 /CNT paper cathodes deliver impressive electrochemical performance, demonstrating an initial discharge capacity of 755.3 mAh g−1 and remaining a high reversible capacity of 642.6 mAh g−1 after 400 cycles at 2 C with an inconspicuous decay of 0.04% per cycle. The bimetallic oxide CoFe 2 O 4 nanoparticles anchored on the carbon nanotube paper is proposed as free-standing sulfur host with enhanced polysulfide trapping and catalytic effects for advanced Li-S batteries. [Display omitted] • Binder-free host realizes high sulfur loading and energy density for Li-S battery. • CoFe 2 O 4 /CNT paper inhibits the polysulfide shuttling via strong chemical interaction. • CNT-anchored CoFe 2 O 4 catalytically promotes the polysulfide conversion kinetics. • The Li-S battery with S/CoFe 2 O 4 /CNT cathode exhibits enhanced capacity and stability. [ABSTRACT FROM AUTHOR]

Li 4 Ti 5 O 12 nanosheet and Li 4 Ti 5 O 12 nanosheet/CNT nanocomposite were prepared in ethyl alcohol medium by a low-cost hydrothermal method. The CNTs are incorporated into the Li 4 Ti 5 O 12 nanosheet homogenously, and then provide a highly conductive network for electron transportation. Li 4 Ti 5 O 12 nanosheet/CNT composite with 4 wt.% CNTs exhibits excellent rate capability and superior cycle life between 1 and 2.5 V. Li 4 Ti 5 O 12 nanosheet/CNTs (4 wt.%) shows superior rate performance with discharge capacities of 137.5 mAh g − 1 at 2 C charge–discharge rate after 90 cycles and 128.3 mAh g − 1 at 3 C charge–discharge rate after 120 cycles. The significantly improved rate capability of the Li 4 Ti 5 O 12 nanosheet/CNT electrodes can be mainly ascribed to the reduced resistance and polarization and improved lithium diffusion coefficient. The same strategy adopted in this work could be helpful to develop advanced electrochemical energy storage systems with long cycle life and high rate performance. [ABSTRACT FROM AUTHOR]