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Synaptic devices based on 2D materials are being considered as potential solutions to mimic the behavior of synapses in neuromorphic computing.

Super broadband optical absorbers with ultrathin films have been keenly pursued for a long time. Although highly lossy materials with sharp light attenuation have the potential to become super absorbers, a large percent of light from free space is inevitably reflected back for the distinct impedance mismatch. Here, a simple strategy, of which reducing the thickness of highly-lossy thin films to minish reflectance and simultaneously folding the ultrathin films to make light multiple pass through, is proposed to obtain super broadband mid-infrared absorbers with ultrathin films. Along this line, the absorbers were prepared by depositing Al-doped ZnO film on scaffolds consisted of alumina spherical shells, whose substrates were opaque. When the thickness of Al-doped ZnO is 43 nm and the layer number of scaffolds is three, a maximum average absorptance was achieved as 97.6% over the wavelength range from 3 to 15 μm. Applying this strategy on polished Al foil, excellent infrared camouflage performance on human-body background was demonstrated. Featured by the strong broadband optical absorption with ultrathin films, flexible access to multiple substrates and low-cost procedures, this approach has the potential in widespread applications of infrared thermal emitters and optoelectronic devices.

High-performance silicon anodes with stable cycling and favorable flexibility are achieved by surface modification and structural design.

Molybdenum disulfide (MoS2) based electronic devices, particularly field effect transistors, have outstanding performance.

Low-dimensional materials are bringing significant innovations to

The bottom-up approach to directly synthesizing low-dimensional materials with outstanding performance has extended the material basis for the next generation integrated circuit industry. All the low-dimensional semiconductors, metals, dielectrics, and their heterojunctions are very promising bricks to build faster and more efficient chips because of their atomically smooth surface and interfaces. The greatest challenge in the synthesis of nanomaterials is how to precisely control the structure, crystalline orientation, defects, dimensions, etc. In past decades, both the methodology and the mechanism of synthesis have been systematically investigated to improve the controllability. However, few studies focused on sensing the synthesis processes in situ and responding to the synthesis immediately. Here, we propose the concept of intelligent synthesis in which the final product can be automatically fine-controlled by a closed loop including in situ monitoring and real-time interventions. As a model system, a high-temperature-tolerant circuit is fabricated on the single-walled carbon nanotube (SWCNT) growth substrate for sensing and responding to the synthesis processes. As a result, either highly pure semiconducting (s-) SWCNT arrays or metallic-semiconducting (m-s) junction arrays with different junction positions is simply synthesized by programming the responding signal. The intelligent synthesis shows much higher efficiency and controllability compared to conventional methods and will lead to the next leap in nanotechnology.

Low-dimensional semiconductors have shown great potential in switches for their atomically thin geometries and unique properties. It is significant to achieve new tunneling transistors by the efficient stacking methodology with low-dimensional building blocks. Here, we report a one-dimensional (1D)-two-dimensional (2D) mixed-dimensional van der Waals (vdW) heterostructure, which was efficiently fabricated by stacking an individual semiconducting carbon nanotube (CNT) and 2D MoS2. The CNT-MoS2 heterostructure shows specific reconfigurable electrical transport behaviors and can be set as a nn junction, pn diode, and band-to-band tunneling (BTBT) transistor by gate voltage. The transport properties, especially BTBT, could be attributed to the electron transfer from MoS2 to CNT through the ideal vdW interface and the 1D nature of the CNT. The progress suggests a new solution for tunneling transistors by making 1D-2D heterostructures from the rich library of low-dimensional nanomaterials. Furthermore, the reconfigurable functions and nanoscaled junction show that it is prospective to apply CNT-MoS2 heterostructures in future nanoelectronics and nano-optoelectronics.

We report the design and simple spray coating fabrication process of a perfect absorber based on carbon nanotubes (CNTs) and carbon black particles with omnidirectional high absorption efficiency beyond 99.9% over the broad wavelength range from 400 nm to 20 μm. The carbon black particles are introduced into the CNT solution to form multi-scale all-carbon-based nanomaterials, effectively modifying the morphology of the sprayed layer to improve the light absorption. The promising absorption characteristics of the CNT–carbon black layer are attributed to not only the intrinsic optical properties of the carbon nanomaterials but also the unique surface nanostructures that efficiently trap light. In addition to serving as absorbers in the coating layer, the CNTs, more importantly, act as connectors between carbon black particles for absorber preparation at a large scale, which is the key to modifying the surface morphology. The all-carbon-based coating layer is also shown to be effective for solar thermal harvesting and self-cleaning function. The developed mixing method for CNTs and carbon black particles in solutions opens a new path for the realization of multi-functional sprayed layers based on CNTs and advances the technology of CNT coatings for scale-up to industry applications.

Lithium metal anodes have a high theoretic capacity and are considered the promising electrodes for high energy density rechargeable batteries. However, the uneven deposition of lithium and lithium dendrites hinders the practical usage of lithium metal anodes. In order to solve this problem, carbon nanotube aerogels coated with amorphous carbon (AC@CNT aerogels) are used as the host, and molten lithium infuses into the carbon aerogels to obtain composite lithium metal anodes. The self-standing, porous AC@CNT aerogels provide a solid structure for lithium deposition/stripping and effectively reduce the local current density, so that lithium dendrites are suppressed and better electrochemical performances are achieved. Compared with the bare lithium metal anodes, the AC@CNT aerogel/lithium metal (AC@CNT/Li) anodes exhibit a longer cycling life of 500 h at deposition/striping capacity of 1 mAh cm−2 on symmetric cells, better cycling performance of 152 mAh g−1 at 0.1C in lithium cobalt oxide/lithium (LCO/Li) cells, and 120.3 mAh g−1 at 1 C in lithium iron phosphate/Li (LFP/Li) cells, demonstrating the potential of the AC@CNT/Li electrodes in developing high-performance lithium-metal batteries.

A much stronger interfacial gating effect was observed in the graphene/HfO2/Si photodetector when compared with that in the graphene/SiO2/Si photodetector. We found that this improvement was due to the higher interface state density at the HfO2/Si interface and the higher dielectric constant of the HfO2 layer. The photoresponsivity of the graphene/HfO2/Si photodetector is as high as 45.8 A W-1. Germanium and amorphous MoS2 (a-MoS2) were used to prepare graphene/HfO2/Ge and graphene/HfO2/a-MoS2 photodetectors, further demonstrating the high efficiency of the interfacial gating mechanism for photodetection. Because of the 0.196 eV bandgap of a-MoS2, which was verified in our previous report, the graphene/HfO2/a-MoS2 photodetector realized ultrabroadband photodetection over the range from 473 nm (visible) to 2712 nm (mid-infrared) at room temperature with photoresponsivity as high as 5.36 A W-1 and response time as fast as 68 μs, which represent significant improvements from the corresponding properties of the pure a-MoS2 photodetectors in our previous report and are comparable with those of state-of-the-art broadband photodetectors. By taking full advantage of the interfacial gating mechanism, a fast response, high photoresponsivity and ultrabroadband photodetection were achieved simultaneously. These interfacial gated graphene photodetectors also offer simple fabrication and full semiconductor process compatibility. The advantages described here indicate that the proposed photodetectors have significant potential for use in electronic and optoelectronic applications and offer a new path toward the development of ultrabroadband photodetectors.

Ultrathin and flexible layers containing BaTiO3 (BTO) nanoparticles, graphene oxide (GO) sheets, and carbon nanotube (CNT) films (BTO/GO@CNT) are used to trap solvated polysulfides and alleviate the shuttle effect in lithium-sulfur (Li-S) batteries. In the functional layers, the CNT films build a conductive framework, and the GO sheets form a support membrane for the uniform dispersion of BTO nanoparticles. BTO nanoparticles without ferroelectricity (nfBTO) can trap polysulfides more effectively by chemical interaction compared to BTO nanoparticles with ferroelectricity (fBTO). A Li-S cell with the nfBTO/GO@CNT functional layer exhibits a reversible capacity of 824.5 mA h g-1 over 100 cycles at 0.2 C. At a high sulfur loading of 5.49 mg cm-2, an electrode with the functional layer shows an areal capacity of 5.15 mA h cm-2 at 0.1 C, demonstrating the nfBTO/GO@CNT functional layer's potential in developing high-performance Li-S batteries.

By using superaligned carbon nanotube (SACNT) macrostructures as reinforcements, the one-step homoepitaxial growth of SACNT/graphite composites was achieved with a home-built experimental setup at temperatures as high as 2600 °C. Compared with traditional furnace heating method, this approach offers the advantages of increased convenience, high throughput and energy efficiency. This high-temperature homoepitaxy strategy was applied to three kinds of structures: SACNT yarn, SACNT film, and SACNT array. Because of the high temperature which exceeded 1800 °C, the samples after high-temperature homoepitaxy showed increased G/D peak area ratios in the Raman spectra, enhanced mechanical properties and improved thermal properties, all of which can meet the requirements of various applications.

Three dimensional TiO2–Au cross-nanoporous structure (3D TiO2–Au CNS) as an efficient photoelectrocatalytic system was fabricated using superaligned carbon nanotube films as etching masks and electron-beam evaporation. The 3D TiO2–Au CNS exhibited a broad absorption band in the visible region, and the incident photon-to-current conversion efficiency of 3D TiO2–Au CNS/Ti electrode was 3–4 times higher than that of pure TiO2 electrode. The photocurrent density of the 3D TiO2–Au CNS device was 0.079 mA cm−2 at 0 V vs. Ag/AgCl with a solar irradiance of 100 mW cm−2. This developed preparation method was simple, of high flexibility and can be adopted for mass production due to its low cost and good compatibility with other processing technologies. The 3D TiO2–Au CNS and its preparation method have important value in design of photoelectrocatalytic system for research and practical applications, which may have a potential utility in photocatalytic and other photoelectrocatalytic reactions.

A strategy to produce sulfur (S) cathodes with ultrahigh areal capacity for lithium-sulfur (Li–S) batteries is proposed. Porous carbon nanotube (CNT) aerogel@Li2S8 cathodes are obtained by dropping Li2S8 solution into the CNT aerogels that are prepared through a freeze-drying method. The three-dimensional (3D) porous structure of the CNT aerogel provides a complete electron transport network and rapid ion transport channels. Moreover, the rich mesoporous structure has an extreme capillary action on the electrolyte. Numerical simulation shows that in a surprisingly short time (2 μs), the electrolyte can be absorbed into the mesopores by capillary action and reach a stable state, limiting the “shuttle effect” of polysulfides. Based on these unique characteristics, the CNT aerogel@Li2S8 cathode exhibits excellent electrochemical performance. With an extremely high areal S loading of 20 mg cm−2, the cathode shows an ultrahigh areal specific capacity of 22.9 mAh cm−2. For the pouch cell with an areal S loading of 10 mg cm−2 and a low electrolyte/sulfur (E/S) ratio of 7.8 μL mg−1, the areal specific capacity reaches a high value of 10.4 mAh cm−2.

It is of great importance to develop new micro-actuators with high performance by optimizing the structures and materials. Here we develop a VO2/Al2O3/CNT eccentric coaxial nanofiber, which can be potentially applied as a micro-actuator. The specific eccentric coaxial structure was efficiently fabricated by conventional thin film deposition methodology with individual CNT templet. Activated by thermal and photothermal stimuli, the as-developed actuator delivers a bidirectional actuation behavior with large amplitudes and an ultra-fast response, ∼ 2.5 mS. A tweezer can be further made by assembling two such nanofibers symmetrically onto a tungsten probe. Clamping and unclamping can be realized by laser stimulus. More experimental and simulation investigations indicated that the actuation behaviors could be attributed to the nanostructured eccentric coaxial geometry, the thermal coefficient mismatch between layers and the fast phase transition of VO2. The micro-actuators will have potentials in micro manipulators, nanoscaled switches, remote controls and other autonomous systems. Furthermore, a large variety of coaxial and eccentric coaxial nanofibers with various functions can also be developed, giving the as-developed methodology more opportunities.

We report the design and simple fabrication process of a perfect absorber based on carbon nanotube films, which enable omnidirectional high absorption efficiency over the wavelength range from 250 nm to 20 μm with polarization independence. The absorber is fabricated using layers of super-aligned carbon nanotube (SACNT) films assembled in a unique manner, which could be easily prepared on stretchable or rigid substrates or suspended. The promising absorption characteristics of the SACNT films were attributed to not only the intrinsic optical properties of the carbon nanomaterials but also the unique surface nanostructures that efficiently trapped light. Moreover, the absorber and its fabrication method exhibit excellent compatibility with various composed materials and treatment processes. Through combination with ultraviolet-curable resist, a robust, ultrathin, and ultralight absorber with good mechanical properties was fabricated on stretchable substrates. The developed fabrication method opens a new path to realize high absorption performance using carbon nanomaterials and the obtained absorber has broad prospects in aerospace and military applications.

Low-dimensional semimetal–semiconductor (Sm-S) van der Waals (vdW) heterostructures have shown their potentials in nanoelectronics and nano-optoelectronics recently. It is an important scientific issue to study the interfacial charge transfer as well as the corresponding Fermi-level shift in Sm-S systems. Here we investigated the gate-tunable contact-induced Fermi-level shift (CIFS) behavior in a semimetal single-walled carbon nanotube (SWCNT) that formed a heterojunction with a transition-metal dichalcogenide (TMD) flake. A resistivity comparison methodology and a Fermi-level catch-up model have been developed to measure and analyze the CIFS, whose value is determined by the resistivity difference between the naked SWCNT segment and the segment in contact with the TMD. Moreover, the relative Fermi-level positions of SWCNT and two-dimensional (2D) semiconductors can be efficiently reflected by the gate-tunable resistivity difference. The work function change of the semimetal, as a result of CIFS, will naturally introduce a modified form of the Schottky–Mott rule, so that a modified Schottky barrier height can be obtained for the Sm-S junction. The methodology and physical model should be useful for low-dimensional reconfigurable nanodevices based on Sm-S building blocks.

A strategy of lattice-reversible binary intermetallic compounds of metallic elements is proposed for applications in flexible lithium-ion battery (LIB) anode with high capacity and cycling stability. First, the use of metallic elements can ensure excellent electronic conductivity and high capacity of the active anode substance. Second, binary intermetallic compounds possess a larger initial lattice volume than metallic monomers, so that the problem of volume expansion can be alleviated. Finally, the design of binary intermetallic compounds with lattice reversibility further improves the cycle stability. In this work, the feasibility of this strategy is verified using an indium antimonide (InSb) system. The volumetric expansion and lithium storage mechanism of InSb are investigated by in situ Raman characterization and theoretical calculations. The active material utilization is significantly improved and the growth of In whiskers is inhibited in the micron-sized ball-milled and carbon coated InSb (bInSb@C) anode, which exhibits a reversible capacity of 733.8 mAh g-1 at 0.2 C, and provides a capacity of 411.5 mAh g-1 after 200 cycles at 3 C with an average Coulombic efficiency of 99.95%. This strategy is validated in pouch cells, illustrating the great potential of lattice-reversible binary intermetallic compounds for use as commercial flexible LIB anodes.

Mixed-dimensional van der Waals (vdW) heterostructures composed of one-dimensional (1D) and two-dimensional (2D) materials have exhibited great potential in nanoelectronics and nano-optoelectronics...

Photodetectors with the ability to detect light over a broad spectral range at room temperature (RT) are attracting considerable attention because of their wide range of potential applications in e...

The development of wires and cables that can tolerate extremely high temperatures will be very important for probing extreme environments, such as in solar exploration, fire disasters, high-temperature materials processing, aeronautics and astronautics. In this paper, a lightweight I high-temperature coaxial h-boron nitride (BN)/carbon nanotube (CNT) wire is synthesized by the chemical vapor deposition (CVD) epitaxial growth of h-BN on CNT yarn. The epitaxially grown h-BN acts as both an insulating material and a jacket that protects against oxidation. It has been shown that the thermionic electron emission (1,200 K) and thermally activated conductivity (1,000 K) are two principal mechanisms I for insulation failure of h-BN at high temperatures. The thermionic emission of h-BN can provide the work function of h-BN, which ranges from 4.22 to 4.61 eV in the temperature range of 1,306-1,787 K. The change in the resistivity of h-BN with temperature follows the ohmic conduction model of an insulator, and it can provide the "electron activation energy" (the energy from the Fermi level to the conduction band of h-BN), which ranges from 2.79 to 3.08 eV, corresponding to a band gap for h-BN ranging from 5.6 to 6.2 eV. However, since the leakage current is very I small, both phenomena have no obvious influence on the signal transmission at the working temperature. This lightweight coaxial h-BN/CNT wire can tolerate 1,200 °C in air and can transmit electrical signals as normal. It is hoped that this lightweight high-temperature wire will open up new possibilities for a wide range of applications in extreme high-temperature conditions.

A high-performance exciton–localized surface plasmon (LSP) coupling system consisting of well-designed plasmonic nanostructures and CdSe/ZnS quantum dots (QDs) was fabricated by first introducing a Ta2O5 layer as both an adhesive coating and coupling medium. It is shown that a larger emission enhancement factor of 6 from CdSe/ZnS QDs can be obtained from the strong coupling effect between QDs and triprism Au nanoarrays and the high scattering efficiency of LSPs without damping. This can be attributed to the matching conditions and a low extinction coefficient with little damping absorption of the Ta2O5 layer in the system. The radiative scattering rate of ΓLSPs can make a contribution to the spontaneous emission rate Γ and thus improve the internal quantum yield of the QDs. This strategy could be promising for practical application of metal-modified fluorescence enhancement.

Significance Spatial resolution can be electrically switched between high-resolution mode (HRM) and low-resolution mode in mixed-dimensional heterostructured photodetectors, and an interference fringe with 334 nm in period can be discriminated by setting at HRM. This can be attributed to the asymmetric geometry and the gate-tunable Fermi levels of these low-dimensional materials. It reveals great potential of the mixed-dimensional architectures in future nanoelectronics and nano-optoelectronics., Low-dimensional nanomaterials, such as one-dimensional (1D) nanomaterials and layered 2D materials, have exhibited significance for their respective unique electronic and optoelectronic properties. Here we show that a mixed-dimensional heterostructure with building blocks from multiple dimensions will present a synergistic effect on photodetection. A carbon nanotube (CNT)–WSe2–graphene photodetector is representative on this issue. Its spatial resolution can be electrically switched between high-resolution mode (HRM) and low-resolution mode (LRM) revealed by scanning photocurrent microscopy (SPCM). The reconfigurable spatial resolution can be attributed to the asymmetric geometry and the gate-tunable Fermi levels of these low-dimensional materials. Significantly, an interference fringe with 334 nm in period was successfully discriminated by the device working at HRM, confirming the efficient electrical control. Electrical control of spatial resolution in CNT–WSe2–graphene devices reveals the potential of the mixed-dimensional architectures in future nanoelectronics and nano-optoelectronics.

Transition-metal dichalcogenides are promising challengers to conventional semiconductors owing to their remarkable electrical performance and suppression of short-channel effects (SCEs). In particular, monolayer molybdenum disulfide has exhibited superior suppression of SCEs owing to its atomic thickness, high effective carrier mass, and low dielectric constant. However, difficulties still remain in large-scale stable fabrication of nanometer-scale channels. Herein, a method to fabricate electrodes with sub-10 nm gaps was demonstrated using horizontally aligned single-walled carbon nanotubes as an evaporation mask. The widths of the nanogaps exhibit robust stability to various process parameters according to the statistical results. Based on these nanogaps, ultrashort-channel length monolayer MoS2 field-effect transistors were produced. Monolayer MoS2 devices with a 7.5 nm channel length and a 10 nm thick HfO2 dielectric layer exhibited excellent performances with an ON/OFF ratio up to 107, a mobility of 17.4 cm2/V·s, a subthreshold swing of about 120 mV/dec, and a drain-induced barrier lowering of about 140 mV/V, all of which suggest a superior suppression of SCEs. This work provides a universal and stable method for large-scale fabrication of ultrashort-channel 2D-material transistors.

Low-dimensional semiconductors have shown great potential in switches for their atomically thin geometries and unique properties. It is significant to achieve new tunneling transistors by the efficient stacking methodology with low-dimensional building blocks. Here, we report a one-dimensional (1D)-two-dimensional (2D) mixed-dimensional van der Waals (vdW) heterostructure, which was efficiently fabricated by stacking an individual semiconducting carbon nanotube (CNT) and 2D MoS

Ultrathin and flexible layers containing BaTiO

Super-aligned carbon nanotube (SACNT) films with wrinkled structures are prepared by a biaxial pre-strain method and can withstand repetitive stretching of large strains in multiple directions. Ultra-stretchable supercapacitors were fabricated with the SACNT film and active carbon (AC) powders. The initial specific capacitance without strain and with 150% strains in the X, Y and 45° axes was 91, 88, 89 and 90 F g-1, respectively. Moreover, the capacitance retentions were 97%, 98.5% and 98.6% after 2000 tensile cycles at 0-150% strain in the X, Y and 45° axes, respectively, demonstrating the excellent strain durability of the SACNT/AC supercapacitors. The stretchable circuit with the combination of stretchable SACNT/AC supercapacitors and SACNT conductors demonstrates a promising method in developing self-contained stretchable functional devices for a variety of applications. The low-cost and scalable biaxial pre-strain process presents a potential route for designing high performance stretchable electronic and energy storage devices.

On-chip torsion balance with a CNT suspension wire and a graphene/Al ultrathin mirror is capable of detecting femtonewton force., The torsion balance, consisting of a rigid balance beam suspended by a fine thread, is an ancient scientific instrument, yet it is still a very sensitive force sensor to date. As the force sensitivity is proportional to the lengths of the beam and thread, but inversely proportional to the fourth power of the diameter of the thread, nanomaterials should be ideal building blocks for torsion balances. Here, we report a torsional balance array on a chip with the highest sensitivity level enabled by using a carbon nanotube as the thread and a monolayer graphene coated with Al nanofilms as the beam and mirror. It is demonstrated that the femtonewton force exerted by a weak laser can be easily measured. The balances on the chip should serve as an ideal platform for investigating fundamental interactions up to zeptonewton in accuracy in the near future.

Developing hybrid supercapacitor-battery energy storage devices for applications in electric vehicles is attractive because of their high energy density and short charge/discharge time. In this study, flexible MnO2 nanoparticle-coated air-oxidized carbon nanotube (MnO2/aCNT) electrodes are fabricated by the in situ redox reaction of KMnO4 and aCNTs at room temperature. The MnO2 nanoparticles have diameters of ∼10 nm. There is a strong chemical interaction between the MnO2 active material and aCNTs as a result of the Mn–O–C linkage. The flexible aCNT network can alleviate the strain from the MnO2 volume change and maintain the electrode integrity during rapid charge/discharge. The aCNT framework also provides a continuous and rapid electron pathway and ensures uniform dispersion of the MnO2 nanoparticles. The presence of MnO2 nanoparticles provides short pathways for Li-ion diffusion and allows interfacial capacitive lithium storage for ultrafast and reversible lithium storage. We report the best high-current performance to date for MnO2/C electrodes, of 395.8 mA h g−1 at 10 A g−1, and 630.2 mA h g−1 after 150 cycles at 2 A g−1. The excellent electrochemical performance, combined with the capacitive dominating process of the electrode, will further the design of high-performance hybrid supercapacitor-battery energy storage devices.

Polyimide (PI) is a high-performance polymer with ultrahigh heat stability while carbon nanotube (CNT) possesses high mechanical strength, excellent electrical and thermal conductivity. Here we report a facile and low-cost method free from CNT pre-dispersion for fabricating super-aligned carbon nanotube (SACNT)/PI composite film which combines the advantages of both SACNT and PI. Flexible and scratch-resistant composite film with high CNT content, uniform dispersion of CNTs, and controlled patterned CNT structures can be fabricated easily via in situ imidization. The SACNT/PI composite film exhibits improvement in mechanical strength, Young's modulus, electrical conductivity compared with pristine PI, and shows good thermal stability. Thanks to these superb properties, a flexible, stable, addressable, electromagnetic wave permeable, and high-temperature fast-response multifunctional heater as well as a thermo-mechanical actuator based on SACNT/PI composite film have been demonstrated in this paper. And it also shows great potential in a variety of applications such as flexible/wearable electronics, RFID, other thermo-related devices and so on.

Black phosphorus (BP) is a promising electrode material with high energy density for lithium-ion batteries. However, volumetric expansion of BP upon lithiation leads to rapid capacity fading of the electrode. Herein, BP composite electrodes are prepared by mixing microsized BP particles with carbon nanotubes and KetjenBlack as dual conducting agents, which facilitate the construction of stable and conductive networks in the electrodes. An ultrathin TiO2 nanocoating is deposited on the surface of the BP composite electrode by electron-beam evaporation. The TiO2 nanocoating acts as a protective layer to prevent the BP particles from directly contacting the electrolyte by forming a LixTiyOz passivation coating on the electrode surface. The LixTiyOz passivation layer suppresses propagation of the formed irreversible solid electrolyte interlayer on the BP particles, resulting in an improved Coulombic efficiency of the BP electrode. Moreover, the LixTiyOz passivation layer facilitates lithium-ion diffusion and ...

The fabrication of high-performance cathodes with high sulfur content is essential for the practical realization of lithium–sulfur (Li–S) systems. The preparation of high-sulfur-content electrodes is currently hindered by poor dispersion of the conductive agents; nonuniformly distributed conductive agents cannot provide sufficient sulfur-loading sites, thereby resulting in aggregation of sulfur/Li2S and severe polarization. To deal with this issue, we prepare CO2 modified carbon nanotube (CNT)-based cathodes for Li–S batteries. CNTs are exposed to CO2 at 900 °C, resulting in uniformly distributed negative charges on the external surface of the tubes; the electrostatic repulsion facilitated the dispersion of CNTs. Compared with the previous work on CNTs prepared by air oxidation (denoted as air-CNTs), the dispersions of the CO2-treated CNTs (denoted as CO2-CNTs) are more stable, which allows higher sulfur loading and improves sulfur utilization. A free-standing CO2-CNT&S electrode with a sulfur content of 80 wt% is fabricated through a sonication-assisted method. The excellent dispersion of the CO2-CNT&S network results in little kinetic barriers, low polarization, and fast charge transport at the interface of the electrode and electrolyte. The CO2-CNT&S electrode delivers a lower capacity fading rate and superior rate performance compared with the air-CNT&S electrode.

Ultrathin and lightweight MoS2/carbon nanotube (CNT) interlayers are developed to effectively trap polysulfides in high-performance lithium–sulfur (Li–S) batteries. The MoS2/CNT interlayer is constructed by loading MoS2 nanosheets onto a cross-stacked CNT film. The CNT film with excellent conductivity and superior mechanical properties provides the Li–S batteries with a uniform conductive network, a supporting skeleton for the MoS2 nanosheets, as well as a physical barrier for the polysulfides. Moreover, chemical interactions and bonding between the MoS2 nanosheets and the polysulfides are evident. The electrode with the MoS2/CNT interlayer delivers an attractive specific capacity of 784 mA h g−1 at a high capacity rate of 10 C. In addition, the electrode demonstrates a high initial capacity of 1237 mA h g−1 and a capacity fade as low as −0.061% per cycle over 500 charge/discharge cycles at 0.2 C. The problem of self-discharge can also be suppressed with the introduction of the MoS2/CNT interlayer. The simple fabrication procedure, which is suitable for commercialization, and the outstanding electrochemical performance of the cells with the MoS2/CNT interlayer demonstrate a great potential for the development of high-performance Li–S batteries.

Innovative three-dimensional (3D) carbon nanotube (CNT)/transition-metal oxide (TMO) sponge electrodes are synthesized by freeze-drying and calcination processes. The high specific surface area and...

The emerging applications of nanoelectromechanical systems (NEMS) in ground-state cooling, quantum manipulation, communication devices, etc., call for a nanoresonator with high frequency, quality factor, and tunability, as well as easy integration. Here we show that such a nanoresonator can be achieved by using a unique assembly technique that transfers the stressed inner shell of carbon nanotubes (CNTs) to a self-aligned device geometry. The as-fabricated nanoresonator shows excellent comprehensive performance, i.e., high frequency (2–3 GHz), high tunability (80–110 MHz/V), high quality factor (3 × 104), and single mode operation. The defect-free nature of the inner shell of the CNT gives rise to a high quality factor, and the preloaded tension improves the resonant frequency and tunability. This resonator with excellent performance also enables the integration of homogeneous devices and will play a key role in the emerging applications of NEMS.