A binder-free nano sulfur–carbon nanotube composite material featured by clusters of sulfur nanocrystals anchored across the superaligned carbon nanotube (SACNT) matrix is fabricated via a facile ...solution-based method. The conductive SACNT matrix not only avoids self-aggregation and ensures dispersive distribution of the sulfur nanocrystals but also offers three-dimensional continuous electron pathway, provides sufficient porosity in the matrix to benefit electrolyte infiltration, confines the sulfur/polysulfides, and accommodates the volume variations of sulfur during cycling. The nanosized sulfur particles shorten lithium ion diffusion path, and the confinement of sulfur particles in the SACNT network guarantees the stability of structure and electrochemical performance of the composite. The nano S-SACNT composite cathode delivers an initial discharge capacity of 1071 mAh g–1, a peak capacity of 1088 mAh g–1, and capacity retention of 85% after 100 cycles with high Coulombic efficiency (∼100%) at 1 C. Moreover, at high current rates the nano S-SACNT composite displays impressive capacities of 1006 mAh g–1 at 2 C, 960 mAh g–1 at 5 C, and 879 mAh g–1 at 10 C.
Endured, low‐cost, and high‐performance flexible perovskite solar cells (PSCs) featuring lightweight and mechanical flexibility have attracted tremendous attention for portable power source ...applications. However, flexible PSCs typically use expensive and fragile indium–tin oxide as transparent anode and high‐vacuum processed noble metal as cathode, resulting in dramatic performance degradation after continuous bending or thermal stress. Here, all‐carbon‐electrode‐based flexible PSCs are fabricated employing graphene as transparent anode and carbon nanotubes as cathode. All‐carbon‐electrode‐based flexible devices with and without spiro‐OMeTAD (2,2′,7,7′‐tetrakis‐(N,N‐di‐p‐methoxyphenylamine)‐9,9′‐spirobifluorene) hole conductor achieve power conversion efficiencies (PCEs) of 11.9% and 8.4%, respectively. The flexible carbon‐electrode‐based solar cells demonstrate superior robustness against mechanical deformation in comparison with their counterparts fabricated on flexible indium–tin oxide substrates. Moreover, all carbon‐electrode‐based flexible PSCs also show significantly enhanced stability compared to the flexible devices with gold and silver cathodes under continuous light soaking or 60 °C thermal stress in air, retaining over 90% of their original PCEs after 1000 h. The promising durability and stability highlight that flexible PSCs are fully compatible with carbon materials and pave the way toward the realization of rollable and low‐cost flexible perovskite photovoltaic devices.
An endurable all‐carbon‐electrode‐based flexible perovskite solar cell is developed, employing graphene as front transparent electrode and carbon nanotubes as back electrode. All‐carbon‐electrode‐based flexible perovskite solar cells with and without the spiro‐OMeTAD (2,2′,7,7′‐tetrakis‐(N,N‐di‐p‐methoxyphenylamine)‐9,9′‐spirobifluorene) hole transport material show power conversion efficiencies of 11.8% and 8.3%, respectively. Moreover, flexible devices demonstrate outstanding bending durability and thermal stability.
A uniform Fe3O4 sheath is magnetron sputtered onto aligned carbon nanotube (CNT) scaffolds that are directly drawn from CNT arrays. The Fe3O4–CNT composite electrode, with the size of Fe3O4 confined ...to 5–7 nm, exhibits a high reversible capacity over 800 mAh g–1 based on the total electrode mass, remarkable capacity retention, as well as high rate capability. The excellent performance is attributable to the superior electrical conductivity of CNTs, the uniform loading of Fe3O4 sheath, and the structural retention of the composite anode on cycling. As Fe3O4 is inexpensive and environmentally friendly, and the synthesis of Fe3O4–CNT is free of chemical wastes, this composite anode material holds considerable promise for high-performance lithium ion batteries.
A superaligned carbon nanotube (CNT) array is a special kind of vertically aligned CNT array with the capability of being converted into continuous films and yarns. The as‐produced CNT films are ...transparent and highly conductive, with aligned CNTs parallel to the direction of drawing. After passing through volatile solutions or being twisted, CNT films can be further condensed into shrunk yarns. These shrunk yarns possess high tensile strengths and Young’s moduli, and are good conductors. Many applications of CNT films and shrunk yarns have been demonstrated, such as TEM grids, loudspeakers, touch screens, etc.
A superaligned carnon nanotube (CNT) array is a special kind of vertically aligned array from which continuous CNT films and yarns can be directly drawn out in a dry state. This approach enables the large‐scale fabrication of CNT devices in a simple process and leads directly to real CNT products, such as TEM grids, loudspeakers, touch screens, etc.
Binder‐free LiCoO2‐SACNT cathodes with excellent flexibility and conductivity are obtained by constructing a continuous three‐dimensional super‐aligned carbon nanotube (SACNT) framework with embedded ...LiCoO2 particles. These binder‐free cathodes display much better cycling stability, greater rate performance, and higher energy density than classical cathodes with binder. Various functional binder‐free SACNT composites can be mass produced by the ultrasonication and co‐deposition method described in this paper.
Designing cost-effective and high-efficiency catalysts to electrolyze water is an effective way of producing hydrogen. Practical applications require highly active and stable hydrogen evolution ...reaction catalysts working at high current densities (≥1000 mA cm
). However, it is challenging to simultaneously enhance the catalytic activity and interface stability of these catalysts. Herein, we report a rapid, energy-saving, and self-heating method to synthesize high-efficiency Mo
C/MoC/carbon nanotube hydrogen evolution reaction catalysts by ultrafast heating and cooling. The experiments and density functional theory calculations reveal that numerous Mo
C/MoC hetero-interfaces offer abundant active sites with a moderate hydrogen adsorption free energy ΔG
(0.02 eV), and strong chemical bonding between the Mo
C/MoC catalysts and carbon nanotube heater/electrode significantly enhances the mechanical stability owing to instantaneous high temperature. As a result, the Mo
C/MoC/carbon nanotube catalyst achieves low overpotentials of 233 and 255 mV at 1000 and 1500 mA cm
in 1 M KOH, respectively, and the overpotential shows only a slight change after working at 1000 mA cm
for 14 days, suggesting the excellent activity and stability of the high-current-density hydrogen evolution reaction catalyst. The promising activity, excellent stability, and high productivity of our catalyst can fulfil the demands of hydrogen production in various applications.
Adaptive camouflage in thermal imaging, a form of cloaking technology capable of blending naturally into the surrounding environment, has been a great challenge in the past decades. Emissivity ...engineering for thermal camouflage is regarded as a more promising way compared to merely temperature controlling that has to dissipate a large amount of excessive heat. However, practical devices with an active modulation of emissivity have yet to be well explored. In this letter we demonstrate an active cloaking device capable of efficient thermal radiance control, which consists of a vanadium dioxide (VO2) layer, with a negative differential thermal emissivity, coated on a graphene/carbon nanotube (CNT) thin film. A slight joule heating drastically changes the emissivity of the device, achieving rapid switchable thermal camouflage with a low power consumption and excellent reliability. It is believed that this device will find wide applications not only in artificial systems for infrared camouflage or cloaking but also in energy-saving smart windows and thermo-optical modulators.
Copper catalyzes the electrochemical reduction of CO to valuable C2+ products including ethanol, acetate, propanol, and ethylene. These reactions could be very useful for converting renewable energy ...into fuels and chemicals, but conventional Cu electrodes are energetically inefficient and have poor selectivity for CO vs H2O reduction. Efforts to design improved catalysts have been impeded by the lack of experimentally validated, quantitative structure–activity relationships. Here we show that CO reduction activity is directly correlated to the density of grain boundaries (GBs) in Cu nanoparticles (NPs). We prepared electrodes of Cu NPs on carbon nanotubes (Cu/CNT) with different average GB densities quantified by transmission electron microscopy. At potentials ranging from −0.3 V to −0.5 V vs the reversible hydrogen electrode, the specific activity for CO reduction to ethanol and acetate was linearly proportional to the fraction of NP surfaces comprised of GB surface terminations. Our results provide a design principle for CO reduction to ethanol and acetate on Cu. GB-rich Cu/CNT electrodes are the first NP catalysts with significant CO reduction activity at moderate overpotential, reaching a mass activity of up to ∼1.5 A per gram of Cu and a Faradaic efficiency >70% at −0.3 V.
Carbon nanotube (CNT) current collectors with excellent flexibility, extremely low density (0.04 mg cm−2), and tunable thickness are fabricated by cross‐stacking continuous CNT films drawn from ...super‐aligned CNT arrays. Compared with metal current collectors, better wetting, stronger adhesion, greater mechanical durability, and lower contact resistance are demonstrated at the electrode/CNT interface. Electrodes with CNT current collectors show improvements in cycling stability, rate capability, and gravimetric energy density over those with metal current collectors. These results suggest that CNT films can function as a promising type of current collector for lightweight and flexible lithium ion batteries with high energy density.
Carbon nanotube (CNT) current collectors with excellent flexibility and extremely low density are fabricated by cross‐stacking continuous CNT films drawn from super‐aligned CNT arrays. The graphite‐CNT electrodes show greater mechanical durability, lower contact resistance, and more than 180% improvement in gravimetric energy density than the graphite‐Cu electrodes, suggesting CNT films as a promising type of current collector in flexible lithium ion batteries.
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.
Display omitted
PDF
