1D Carbon Nanotubes Research Articles

Electrospun 1D and 2D Carbon and Polyvinylidene Fluoride (PVDF) Piezoelectric Nanocomposites

Piezoelectric nanocomposite fibrous membranes consisting of polymer polyvinylidene fluoride (PVDF) as matrix and incorporating 1D carbon nanotubes (CNTs) and 2D graphene oxide (GO) were prepared using an electrospinning process. The influence of the filler type, loading, and dispersion status on the total PVDF crystallinity (Xc); the relative fraction of the β phase (piezoelectric phase) in crystalline PVDF (Fβ); the volume fraction of β phase in the samples (vβ); and the piezoelectric coefficient d33 were investigated. The vβ is used to assess the formation of β phase for the first time, which considered the combined influence of fillers on Xc and Fβ, and is more practical than other investigations using only Fβ for the assessment. The inclusion of all types of carbon fillers had resulted in a considerable reduction in the Xc compared with the neat PVDF, and the Xc decreased with the CNT loading while increased with the GO loading. The addition of CNT and GO had also reduced the Fβ compared with the neat PVDF, and Fβ increased with CNT loading while decreased as GO loading increased. The vβ is significantly reduced by the addition of CNT and GO, while vβ decreases with CNT and GO loading increases. Since the calculation of vβ has considered the combined influence of fillers on Xc and Fβ, both of which were reduced by incorporating CNT and GO, the reduction of vβ was expected. The vβ of the PVDF/CNT composites were higher than that of the PVDF/GO composites. Although it is generally anticipated that d33 increases with vβ, it is observed that in the presence of CNT, d33 is dominated by the increase in electric conductivity of the composites during and after the electrospinning process, giving rise to transport of charges, produced by β crystals within the fiber to the surface of the sample. In addition, the 1D CNTs may have promoted the orientation of β crystals in the d33 direction, therefore, enhancing the d33 of the composites despite the hindrance of the β‐phase formation (i.e., the reduction of vβ). Adding CNTs can also improve piezoelectricity through interfacial polarization, which increases the dielectric constant of composite (mobile charges within CNTs facilitate composite polarization). CNT loadings higher than 0.01 wt.% are sufficient to outperform the neat PVDF, and d33 becomes 59.7% higher than the neat PVDF at 0.03 wt.% loading, but only GO loadings of 0.5 wt.% achieved comparable d33 to the neat PVDF; further increase in GO loading had resulted in a decline in d33. The low conductivity of GO, the influence of flocculation, and the lower aspect ratio compared with CNT may result in lower electron transfer and less orientation of the β‐phase polycrystalline. The d33 of the PVDF/CNT composites is higher than that of the PVDF/GO composites despite much higher loading of GO. This study aims to contribute to the development of PVDF nanocomposites in piezoelectric energy harvesting applications (e.g., self‐powered biosensors and wireless sensor networks).

CNT supported NiO hierarchal nanostructure on stainless steel substrate for efficient field emitters

The field emission application has recently focused on assembling nanoscale building blocks into three-dimensional (3D) hierarchical or hybrid nanostructure. The hierarchical nanostructure provides better field emission than a single nanostructure. In the present study, the chemical vapor deposition (CVD) method was used to synthesize 1D carbon nanotube (CNT) on stainless steel (SS) substrate. Nickel (Ni) was then sputtered on the synthesized CNT, and the sputtered substrate was treated hydrothermally in LiOH solution. The deposited Ni on CNT forms Ni(OH)2, and after oxidation, it was converted to NiO nanostructure. The structure, morphology, and chemical state of the samples were characterized by XRD, FESEM, Raman spectroscopy, and XPS. The SS-CNT exhibited a turn-on field and maximum emission current of 5.5 V/μm and 275 µA/cm2, respectively. However, SS-CNT-Ni demonstrated reduced field emission responses with turn-on field and maximum current 8.7 V/μm and 68 µA/cm2, respectively. The field emission response has been enhanced in the case of the SS-CNT-NiO sample as compared to the other structures. The turn-on field and maximum current densities were 5.1 V/µm and 719 µA/cm2 for the SS-CNT-NiO, respectively.

Co-Axial Fabrication of Ni-Co Layered Double Hydroxide into 3d Carbon Nanotube Networks for High-Performance Flexible Fiber Supercapacitors

Co-Axial Fabrication of Ni-Co Layered Double Hydroxide into 3d Carbon Nanotube Networks for High-Performance Flexible Fiber Supercapacitors

Less-Energy Consumed Hydrogen Evolution Coupled with Electrocatalytic Removal of Ethanolamine Pollutant in Saline Water over Ni@Ni3 S2 /CNT Nano-Heterostructured Electrocatalysts.

Energy crises, environmental pollution, and freshwater deficiency are critical issues on the planet. Electrolytic hydrogen generation from saline water, particularly from salt-contained hazardous wastewater, is significant to both environment and energy concerns but still challenging due to the high energy cost, severe corrosion, and the absence of competent electrocatalysts. Herein, a novel strategy is proposed for energy-efficient hydrogen production coupled with electro-oxidation removal of ethanolamine pollutant in saline water. To achieve this, an active and durable heterostructured electrocatalyst is developed by in situ growing Ni@Ni3 S2 core@shell nanoparticles in cross-linked 3D carbon nanotubes' (CNTs) network, achieving high dispersibility and metallic property, low packing density, and enriched exposed active sites to facilitate fast electron/mass diffusion. The unique Ni@Ni3 S2 /CNTs nano-heterostructures are competent for long-term stably electro-oxidizing environmental-unfriendly ethanolamine at a high current density of 100mA cm-2 in saline water, which not only suppresses oxygen and chloride evolution reactions but also decreases the energy consumption to boost hydrogen production. Associated with experimental results, density functional theory studies indicate that the collaborative adsorption of electrolyte ions and ethanolamine molecules can synergistically modulate the adsorption/desorption properties of catalytic active centers on Ni@Ni3 S2 /CNTs surface, leading to long-term stabilized electrocatalysis for efficient ethanolamine oxidation removal and less-energy hydrogen simultaneous production in saline water.

Comparative Electrocatalytic Oxygen Evolution Reaction Studies of Spinel NiFe2O4 and Its Nanocarbon Hybrids

Electrocatalytic oxygen evolution reaction (OER) is one of the crucial reactions for converting renewable electricity into chemical fuel in the form of hydrogen. To date, there is still a challenge in designing ideal cost-effective OER catalysts with excellent activity and robust durability. The hybridization of transition metal oxides and carbonaceous materials is one of the most effective and promising strategies to develop high-performance electrocatalysts. Herein, this work synthesized hybrids of NiFe2O4 spinel materials with two-dimensional (2D) graphene oxide and one-dimensional (1D) carbon nanotubes using a facile solvothermal approach. Electrocatalytic activities of NiFe2O4 with 2D graphene oxide toward OER were realized to be superior even to the 1D carbon nanotube-based electrocatalyst in terms of overpotential to reach a current density of 10 mA/cm2 as well as Tafel slopes. The NiFe2O4 with 2D graphene oxide hybrid exhibits good stability with an overpotential of 327 mV at a current density of 10 mA/cm2 and a Tafel slope of 103 mV/dec. The high performance of NiFe2O4 with 2D graphene oxide is mainly attributed to its unique morphology, more exposed active sites, and a porous structure with a high surface area. Thus, an approach of hybridizing a metal oxide with a carbonaceous material offers an attractive platform for developing an efficient electrocatalyst for water electrochemistry applications.

Boost the cyclability and Na+ diffusion kinetics of Sb2S3 anode by CNTs cross-linking N-doped carbon matrix

Antimony sulfides exhibit a tremendous potential owing to the high theoretical specific capacity from multiple redox storage mechanisms for sodium-ion batteries (SIBs). However, these bottlenecks, including low electrical conductivity, poor ionic diffusion kinetics, and severe volume expansion, still restrict the development of antimony sulfide as SIBs anodes. Meanwhile, in view of long-term interests and practical application, the cost-efficient preparation methods become an imminent challenge to the advancement of high-performance SIBs anodes. Here, a novel three-step strategy, composed of co-precipitation, heat reduction processes, and sulfation conversion, was utilized to construct a “reinforced concrete” architecture, in which Sb2S3 nanoparticles embedded in N-doped carbon matrix (NC) modified by carbon nanotubes (CNTs), denoted as Sb2S3/CNTs/NC. As the “cement block”, the N-doped 3D carbon matrix can promote the electron migration and reduce the aggregation of active materials upon cycling. In terms of “rebars” (i.e., 1D CNTs) for ensuring the anode integrality during incessant sodiation/de-sodiation processes, they function as binders and stabilizers, which intimately cross-link with Sb2S3 nanoparticles and carbon matrix, accommodate the volume change, and maintain the fast transfer of electron transfer inside the whole composite. Benefiting from these merits of the hierarchical structure (i.e., 3D NC and 1D CNTs), as an anode for SIBs, Sb2S3/CNTs/NC demonstrates an improved sodium storage capability with an initial specific capacity of 770.80 mAh g−1 at 0.1 A g−1 and a superior initial coulombic efficiency (ICE) of 79.90%. Moreover, even at a high current density of 1.0 A g−1, a reversible capacity of 313.54 mAh g−1 can be delivered after 350 long cycles, indicating the stable cyclicity. The Sb2S3/CNTs/NC with designed construction and enhanced electrochemical performance could provide a new perspective on low-cost, time-saving, and exercisable synthesis approach for high-performance sulfide-based anodes.

An individual sandwich hybrid nanostructure of cobalt disulfide in-situ grown on N doped carbon layer wrapped on multi-walled carbon nanotubes for high-efficiency lithium sulfur batteries

Binding and trapping of lithium polysulfide (LPS) are being conceived as the most effective strategies to improve lithium-sulfur (Li-S) battery performance. Therefore, exploiting a simple but cost-effective approach for the absorption and conversion of LPS and the transfer of electrons and Li+ ions is of paramount importance. Herein, sandwich structure MWCNTs@N-doped-C@CoS2 integrated with multiple nanostructures of zero-dimensional (0D) CoS2 nanoparticles, 1D carbon nanotubes (CNTs), and 2D N-doped amorphous carbon layer was obtained, where MWCNTs was firstly uniformly attached with a polydopamine (PDA) of excellent adhesion, followed by hydrothermal method, the Co2+ nanoparticles were in-situ grown on the PDA by the formation of complex compound of Co2+ and N atoms in PDA, and then the CoS2 nanoparticles were in-situ grown on CNTs in a point-surface contact way by a bridging of N-doped amorphous carbon layer derived from the carbonization of attached PDA after the vulcanization at 500 °C under Ar atmosphere. The multifunction synergism of absorption, conductivity, and the kinetics of LPS redox is significantly improved, consequently effectively suppressing the shuttle effect and tremendously increasing the utilization rate of active substance. For the Li-S battery assembled with MWCNTs@N-doped-C@CoS2-modified separator, its rate capacity and cycling performance can be greatly enhanced. It can exhibit a high initial discharge capacity of 1590 mAh g−1 at 0.1 C, a stable long-term cycling performance with a relatively low capacity decay of 0.07% per cycle during 500 cycles at 1 C, and a reversible capacity of 772 mAh g−1 and a capacity decay of 0.04% per cycle during 250 cycles at 2 C. Even at a large current density of 4 C, an initial specific discharge capacity of 634 mAh g−1 can still be delivered. With a high sulfur loading of 5.0 mg cm−2, additionally, an outstanding cycling stability can also be well maintained at 685 mAh g−1 at 0.1 C after 50 cycles. This work provides a novel and simple but effective strategy to develop such sandwich hybrid materials comprised of polar metal sulfides and conductive networks via an effective bridging to help realize durable and stable Li-S battery.

Extrusion‐Printed CNT–Graphene Sensor Array with Embedded MXene/PEDOT:PSS Heater for Enhanced NO2 Sensing at Low Temperature

AbstractWearable sensors are currently one of the top emerging areas with enormous growth potential. Low‐cost fabrication techniques using simple and scalable printing technologies are making a significant impact on their development. Recent advances in high‐performance gas/vapor sensors based on carbon nanomaterials have shown potential applications ranging from disease diagnostics to environmental monitoring and defences. Herein, a hybrid sensing material of 1D carbon nanotubes (CNTs) and 2D graphene is developed, and a conductive ink is formulated, which is applied for fabricating a nitrogen dioxide (NO2) gas sensor array within a compact design utilizing extrusion printing. To improve NO2‐sensing performance and optimal operating temperature, a reverse‐side layer is designed, which combines MXene and poly(3,4‐ethylenedioxythiophene)‐doped poly(styrene sulfonate) (PEDOT:PSS), and functions as a Joule heater. The printed CNT–graphene‐based sensor with an embedded MXene/PEDOT:PSS heater is capable of detecting trace amounts of NO2 gas (1 ppm) at 65 °C. The sensor is able to distinguish between various gases/volatile organic compounds and target NO2 gas based on their chemical affinities. The printed CNT–graphene sensor array also demonstrates a high‐level of recoverability, satisfied stability, durability, and reproducibility, which render this sensor a suitable candidate for practical applications.

Unearthing of a new science from nanostructured carbons

Graphene, single-wall carbon nanotubes, and porous carbons have zero-dimensional nanowindows, one-dimensional (1D) pores, and three-dimensional pores consisting of two-dimensional (2D) unit pores, respectively. A molecular dynamics simulation study on nanowindows shows that they enable the efficient separation of O2 from N2 and Ar at an extremely high permeance. Intense confinement of sulfur atoms in 1D-carbon nanotube pore spaces in vacuo leads to the formation of metallic 1D-sulfur chains. Evidence of the partial breaking of the Coulombic law for ionic liquids confined as monolayers in 2D pores, which is caused by an evident image charge effect of conductive carbon-pore walls, was provided by hybrid-reverse Monte Carlo simulation-aided X-ray scattering. The solid-like structural formation of oxygen molecules in 2D carbon pores induces highly efficient and rapid adsorption separation of 18O2 from 16O2 near 112 K, which is the boiling point of methane. Abundant water vapor can be adsorbed on microporous carbon through cluster-associated hydrophobic-hydrophilic transformations. Water molecules form aggregated clusters on the adsorbed branch, which transforms into a continuous structure at a relative pressure of 1, giving rise to obvious adsorption hysteresis. Logical and challenging studies to improve our fundamental understanding, along with new approaches, produce completely new findings, even for carbon materials that have been thoroughly studied.

Disperse-and-Mix: Oil as an 'Entrance Door' of Carbon-Based Fillers to Rubber Composites.

Oil was employed as an ‘entrance door’ for loading rubber with carbon-based fillers of different size and dimensionalities: 1D carbon nanotubes (CNTs), 2D graphene nanoplatelets (GNPs), and 3D graphite. This approach was explored, as a proof of concept, in the preparation of tire tread, where oil is commonly used to reduce the viscosity of the composite mixture. Rubber was loaded with carbon black (CB, always used) and one or more of the above fillers to enhance the thermal and mechanical properties of the composite. The CNT-loaded system showed the best enhancement in mechanical properties, followed by the CNT-GNP one. Rubber loaded with both graphite and GNP showed the best enhancement in thermal conductivity (58%). The overall enhancements in both mechanical and thermal properties of the various systems were analyzed through an overall relative efficiency index in which the total filler concentration in the system is also included. According to this index, the CNT-loaded system is the most efficient one. The oil as an ‘entrance door’ is an easy and effective novel approach for loading fillers that are in the nanoscale and provide high enhancement of properties at low filler concentrations.

Activating MoS2 Nanoflakes via Sulfur Defect Engineering Wrapped on CNTs for Stable and Efficient Li‐O2 Batteries

AbstractDeveloping efficient cathode catalysts can largely promote the application of Li‐O2 batteries (LOBs). In this work, the core‐shell MoS2−x@CNTs composite is synthesized via a hydrothermal method with annealing and NaBH4 reduction post‐processing, of which the defective MoS2 nanoflakes are homogeneously coated on the 3D carbon nanotube (CNT) webs. It is found that it delivers superior bifunctional catalytic activities toward both oxygen reduction and evolution reactions for LOBs. On the one hand, the charge re‐distribution on MoS2 nanoflakes with sulfur vacancies can be effectively constructed by the surface engineering strategy, remarkably boosting the kinetics of Li‐O2 catalysis. On the other hand, the conductive and high surface area CNT network can facilitate mass transfer and provide enough free space for composite cathodes, accommodating the volume changes caused by the reversible formation and decomposition of discharge products during cycling. More importantly, the unique core‐shell architecture can not only enable fully covering of defective MoS2 nanoflakes on CNT surfaces to avoid the contact between CNTs and electrolyte, distinctly suppressing side reactions, but also realize the exposure of more active sites to fulfill their catalytic properties. This work provides an insightful investigation on advanced catalysts and holds great potential for catalyst structural engineering in LOBs.

Poly(1,5-diaminonaphthalene)-Grafted Monolithic 3D Hierarchical Carbon as Highly Capacitive and Stable Supercapacitor Electrodes.

A holistic approach to fabricate a hierarchical electrode that consists of redox-active poly(1,5-diaminonaphthalene), 1,5 PDAN, uniformly and conformally grafted onto a 3D carbon nanotube (CNT-a-CC) electrode is set forth. The CNT-a-CC electrode was formed by direct growth of high-density CNTs on the surface of every individual microfiber, the constituent of activated carbon cloth (a-CC). Owing to the naphthalene backbone, conformal deposition of 1,5 PDAN on carbon surfaces has been readily attained via electropolymerization. This hierarchical platform with open and continuous nanochannels formed by CNTs coupled with excellent electrical connectivity between CNTs and the polymer provides a reproducible platform for electrochemical investigation. According to multiple sample analyses on CNT-a-CC, the gravimetric capacitance of 1,5 PDAN is up to 1250 F/g, and this value can be maintained up to 100 mV/s. Hierarchical organization provides a specific capacitance of 650 F/g at 2 mV/s at a 1,5 PDAN loading of 2.5 mg/cm2. The conjugated ladder structure of the polymer led to strong π-π interactions between the polymer and CNT-a-CC together with mechanically robust CNT-a-CC. A capacitance retention of 94% for 1,5 PDAN has been obtained after 25,000 cycles at 100 mV/s, a significant cycle stability improvement over conventional conductive polymers such as polyaniline. This new lightweight electrode that seamlessly integrates functional species with nanochannel-like CNT-a-CC opens up a new opportunity to harness electrochemical reactions in the 3D carbon electrode for energy storage and electrocatalysis as well as electrochemical sensing.

N-doped Porous Host with Lithiophilic Co Nanoparticles Implanted into 3D Carbon Nanotubes for Dendrite-Free Lithium Metal Anodes

N-doped Porous Host with Lithiophilic Co Nanoparticles Implanted into 3D Carbon Nanotubes for Dendrite-Free Lithium Metal Anodes

Hybrid strategy of graphene/carbon nanotube hierarchical networks for highly sensitive, flexible wearable strain sensors

One-dimensional and two-dimensional materials are widely used to compose the conductive network atop soft substrate to form flexible strain sensors for several wearable electronic applications. However, limited contact area and layer misplacement hinder the rapid development of flexible strain sensors based on 1D or 2D materials. To overcome these drawbacks above, we proposed a hybrid strategy by combining 1D carbon nanotubes (CNTs) and 2D graphene nanoplatelets (GNPs), and the developed strain sensor based on CNT-GNP hierarchical networks showed remarkable sensitivity and tenability. The strain sensor can be stretched in excess of 50% of its original length, showing high sensitivity (gauge factor 197 at 10% strain) and tenability (recoverable after 50% strain) due to the enhanced resistive behavior upon stretching. Moreover, the GNP-CNT hybrid thin film shows highly reproducible response for more than 1000 loading cycles, exhibiting long-term durability, which could be attributed to the GNPs conductive networks significantly strengthened by the hybridization with CNTs. Human activities such as finger bending and throat swallowing were monitored by the GNP-CNT thin film strain sensor, indicating that the stretchable sensor could lead to promising applications in wearable devices for human motion monitoring.

High-Energy and High-Power Lithium-Ion Cells Enabled by Electrochemically Derived Carbon Nanotubes

A common approach to increasing packaged cell level energy density is to increase the mass fraction of active materials and decrease that of inactive materials such as conductive and polymeric additives in the electrodes, current collectors, and separators. To increase active materials, thick electrodes have been proposed and studied in the literature as a method for increasing the mass ratio of active materials to current collector foils. However, there are many challenges associated with increasing the thickness of cathodes. Notably, most cathode materials are inherently insulating and therefore require conductive additives to maintain electrical conductivity to facilitate charge transfer from the electrolyte-cathode interface back to the current collector. The length of this pathway increases with thicker cathodes and requires reconsideration of the conductive materials used to form this network. One dimensional (1D) CNTs have been demonstrated recently as superior conductive additives due to their line-to-line contact method and superior active-material surface coverage, which allows them to create a 3D conductive network at a low mass fraction of the electrode. In extreme conditions of battery operations, performance is limited by the inactive materials, rather than the active energy-storing materials in a cell. This holds true for thick coatings, as well as high rates of charge and discharge. Switching from traditional carbon blacks (CB) such as acetylene or furnace black to CNT additives allows for simultaneous improvements in thick electrodes which increase packaged cell-level energy density, as well as increased performance in extreme fast charging environments. SkyNano is commercializing a highly tunable molten-salt electrolysis process to make low-cost carbon nanotubes (CNTs) using electrochemical capture and conversion of atmospheric CO2 utilizing several highly scalable processes. This technology can be harnessed to produce carbon additives with precisely tuned properties to enable ultra-thick cathode coatings with high areal loadings that exhibit superior rate performance.Enabling the widespread commercialization of high-energy, advanced batteries with low cost for transportation electrification, renewable energy storage, and portable electronics will result in substantially reduced GHG emissions, increased mobility, and ubiquitous opportunity for personal connectivity. In addition SkyNano produces its CNTs through the consumption of ambient or flowing CO2 streams, which will contribute to slowing the increase in CO2 emissions and ultimately reducing the current atmospheric content of 420 ppm. CNTs provide many commercial advantages in advanced batteries: 1) using thicker, higher-energy electrodes by minimizing electronic conductivity losses; 2) higher power density (i.e., higher capacity at high discharge rates); 3) integrating multilayer electrode architectures; 4) higher loadings of Si at the anode by forming a more mechanically stable composite with graphite during electrochemical cycling; and 5) faster charging rates approaching 6C. In addition, SkyNano CNTs will be less expensive than current chemical vapor deposited CNTs and optimized for a both multilayer (thick) electrode and all-solid-state battery approaches. The proposed electrode designs rely on the use of conventional electrolytes, widely available active materials, and conventional electrode manufacturing approaches and require no CapEx to integrate into current manufacturing lines.Electrochemical performance data (rate capability, AC impedance, capacity retention during cycling, etc.) is discussed from both molten-salt electrolysis reactor and LIB operation points of view. Single unit-cell (“single-layer”) pouch cells were constructed (five replicates for each cell configuration) using three distinct cathode coatings, which had an average rated capacity of 134 ± 10 mAh. The cathode areal capacities were 3.1 mAh/cm2, and the anodes were 3.4 mAh/cm2, giving an N:P ratio of 1.1. It was found that both formulations F7 and F8 outperformed the Control 2 at all discharge rates above 0.5C. The scaled F7 pouch cells performed better than their half coin cell counterparts and significantly outperformed Control 2 (20.5%, 62.7%, and 46.7% capacity improvements at 2C, 3C, and 5C discharge rates, respectively), showing that only a small amount of CNTs is required to realize large improvements in cathode rate capability.

Confined Polysulfides in N-Doped 3D-CNTs Network for High Performance Lithium-Sulfur Batteries.

Improving the utilization efficiency of active materials and suppressing the dissolution of lithium polysulfides into the electrolyte are very critical for development of high-performance lithium-sulfur batteries. Herein, a novel strategy is proposed to construct a three-dimensional (3D) N-doped carbon nanotubes (CNTs) networks to support lithium polysulfides (3D-NCNT-Li2S6) as a binder-free cathode for high-performance lithium-sulfur batteries. The 3D N-doped CNTs networks not only provide a conductive porous 3D architecture for facilitating fast ion and electron transport but also create void spaces and porous channels for accommodating active sulfur. In addition, lithium polysulfides can be effectively confined among the networks through the chemical bond between Li and N. Owing to the synergetic effect of the physical and chemical confinement for the polysulfides dissolution, the 3D-NCNT-Li2S6 cathodes exhibit enhanced charge capacity and cyclic stability with lower polarization and faster redox reaction kinetics. With an initial discharge capacity of 924.8 mAh g−1 at 1 C, the discharge capacity can still maintain 525.1 mAh g−1 after 200 cycles, which is better than that of its counterparts.

Design of 3D Carbon Nanotube Monoliths for Potential-Controlled Adsorption

The design of 3D monoliths provides a promising opportunity to scale the unique properties of singular carbon nanotubes to a macroscopic level. However, the synthesis of carbon nanotube monoliths is often characterized by complex procedures and additives impairing the later macroscopic properties. Here, we present a simple and efficient synthesis protocol leading to the formation of free-standing, stable, and highly conductive 3D carbon nanotube monoliths for later application in potential-controlled adsorption in aqueous systems. We synthesized monoliths displaying high tensile strength, excellent conductivity (up to 140 S m−1), and a large specific surface area (up to 177 m2 g−1). The resulting monoliths were studied as novel electrode materials for the reversible electrosorption of maleic acid. The process principle was investigated using chronoamperometry and cyclic voltammetry in a two-electrode setup. A stable electrochemical behavior was observed, and the synthesized monoliths displayed capacitive and faradaic current responses. At moderate applied overpotentials (± 500 mV vs. open circuit potential), the monolithic electrodes showed a high loading capacity (~20 µmol g−1) and reversible potential-triggered release of the analyte. Our results demonstrate that carbon nanotube monoliths can be used as novel electrode material to control the adsorption of small organic molecules onto charged surfaces.

High-Sensitivity Flexible Pressure Sensor-Based 3D CNTs Sponge for Human-Computer Interaction.

Researchers are showing an increasing interest in high-performance flexible pressure sensors owing to their potential uses in wearable electronics, bionic skin, and human–machine interactions, etc. However, the vast majority of these flexible pressure sensors require extensive nano-architectural design, which both complicates their manufacturing and is time-consuming. Thus, a low-cost technology which can be applied on a large scale is highly desirable for the manufacture of flexible pressure-sensitive materials that have a high sensitivity over a wide range of pressures. This work is based on the use of a three-dimensional elastic porous carbon nanotubes (CNTs) sponge as the conductive layer to fabricate a novel flexible piezoresistive sensor. The synthesis of a CNTs sponge was achieved by chemical vapor deposition, the basic underlying principle governing the sensing behavior of the CNTs sponge-based pressure sensor and was illustrated by employing in situ scanning electron microscopy. The CNTs sponge-based sensor has a quick response time of ~105 ms, a high sensitivity extending across a broad pressure range (less than 10 kPa for 809 kPa−1) and possesses an outstanding permanence over 4000 cycles. Furthermore, a 16-pixel wireless sensor system was designed and a series of applications have been demonstrated. Its potential applications in the visualizing pressure distribution and an example of human–machine communication were also demonstrated.

Anchoring polyaniline molecule on 3D carbon nanotube meshwork as self-standing cathodes for advanced rechargeable zinc ion batteries

Polyaniline (PANI) is considered as an attractive cathode candidate for advanced rechargeable zinc ion batteries (ZIBs). However, the low reactivity and poor reversibility of its redox processes in neutral electrolytes generally lead to limited capacity and short lifespan. Herein, PANI molecules are strategically anchored onto three-dimensional (3D) carbon nanotube (CNT) meshwork as a self-standing cathode to solve this problem. The as-introduced 3D CNT conductive networks are capable of functioning as the electronic transmission pipelines to accelerate the electron transfer and acting as an electrolyte reservoir to maximum the intimate contact between the PANI and electrolyte, greatly facilitating the redox processes of PANI. The PANI-CNT cathode exhibits a high capacity of 240 mAh g −1 at 0.5 A g −1 , almost twice as much as the bare PANI (123 mAh g −1 ). Furthermore, the PANI-CNT electrode also delivers a superior rate capability, maintaining a decent capacity of 129 mAh g −1 with the increase of the current density to 12 A g −1 . This work sheds light on the performance optimization strategies of polymer cathodes for next-generation rechargeable zinc batteries. • The PANI anchored on 3D carbon nanotube meshwork as self-standing cathode is designed. • The highly crisscrossed CNT networks are in favor of fast electron transfer. • The PANI-CNT electrode delivers a superior capacity of 240 mAh g −1 at 0.5 A g −1 .

State of the Art in the Antibacterial and Antiviral Applications of Carbon-Based Polymeric Nanocomposites.

The development of novel approaches to prevent bacterial infection is essential for enhancing everyday life. Carbon nanomaterials display exceptional optical, thermal, and mechanical properties combined with antibacterial ones, which make them suitable for diverse fields, including biomedical and food applications. Nonetheless, their practical applications as antimicrobial agents have not been fully explored yet, owing to their relatively poor dispersibility, expensiveness, and scalability changes. To solve these issues, they can be integrated within polymeric matrices, which also exhibit antimicrobial activity in some cases. This review describes the state of the art in the antibacterial applications of polymeric nanocomposites reinforced with 0D fullerenes, 1D carbon nanotubes (CNTs), and 2D graphene (G) and its derivatives such as graphene oxide (GO) and reduced graphene oxide (rGO). Given that a large number of such nanocomposites are available, only the most illustrative examples are described, and their mechanisms of antimicrobial activity are discussed. Finally, some applications of these antimicrobial polymeric nanocomposites are reviewed.