Polymer removal and dispersion exchange of (10,5) chiral carbon nanotubes with enhanced 1.5 µm photoluminescence.

Singe-chirality single-walled carbon nanotubes (SWCNTs) produced by selective polymer extraction have been actively investigated for their semiconductor applications. However, to fulfil the needs of biocompatible applications, the organic solvents in polymer-sorted SWCNTs impose a limitation. In this study, we developed a novel strategy for organic-to-aqueous phase exchange, which involves thoroughly removing polymers from the sorted SWCNTs, followed by surfactant covering and redispersing of the cleaned SWCNTs in water. Importantly, the obtained aqueous system allows us to perform sp3 functionalization of the SWCNTs, leading to a strong photoluminescence emission at 1550 nm from the defect sites of (10,5) SWCNTs. These functionalized SWCNTs as infrared light emitters show considerable potential for bioimaging applications. This exchange-and-functionalization strategy opens the door for future biocompatible applications of polymer-sorted SWCNTs.

Iterative Strategy for Sorting Single-Chirality Single-Walled Carbon Nanotubes from Aqueous to Organic Systems.

Significant advancements in electronic devices and integrated circuits have been facilitated by semiconducting single-walled carbon nanotubes (SWCNTs) sorted by conjugated polymers (CPs). However, the variety of CPs with single-chirality selectivity is limited, and the sorting results are strongly dependent on the chiral distribution of the starting materials. To address this, we develop an iterative strategy to achieve single-chirality SWCNT separation from aqueous to organic systems, based on a multistep tandem extraction technique that allows a gentle and nondestructive separation of surfactants from SWCNTs, ensuring an efficient system transfer. In parallel, we refined the iterative sorting process between CPs. Employing two starting materials with narrow diameter distributions, using three CPs, we successfully sorted out five single-chirality SWCNTs of the (9,5), (8,6), (10,5), (8,7), and (11,3) species in organic systems. This strategy bridges the gap between aqueous and organic separation systems, achieving efficient complementarity between them.

Rainbow-Colored Carbon Nanotubes via Rational Surface Engineering for Smart Visualized Sensors.

Surface engineering is effective for developing materials with novel properties, multifunctionality, and smart features that can enable their use in emerging applications. However, surface engineering of carbon nanotubes (CNTs) to add color properties and functionalities has not been well established. Herein, a new surface engineering strategy is developed to achieve rainbow-colored CNTs with high chroma, high brightness, and strong color travel for visual hydrogen sensing. This approach involved constructing a bilayer structure of W and WO3 on CNTs (CNT/W/WO3 ) and a trilayer structure of W, WO3 , and Pd on CNTs (CNT/W/WO3 /Pd) with tunable thicknesses. The resulting CNT/W/WO3 composite film exhibits a wide range of visible colors, including yellow, orange, magenta, violet, blue, cyan, and green, owing to strong thin-film interference. This coloring method outperforms other structural coloring methods in both brightness and chroma. The smart CNT/W/WO3 /Pd films with porous characteristics quickly and precisely detect the hydrogen leakage site. Furthermore, the smart CNT/W/WO3 /Pd films allow a concentration as low as 0.6% H2 /air to be detected by the naked eye in 58 s, offering a very practical and safe approach for the detection and localization of leaks in onboard hydrogen tanks.

Fabrication of high-performance carbon nanotube/copper composite fibers by interface thiol-modification.

Carbon nanotube (CNT)/copper (Cu) composite fibers are placed great expectations as the next generation of light-weight, conductive wires. However, the electrical and mechanical performances still need to be enhanced. Herein, we demonstrate a strategy that is electrodeposition Cu on thiolated CNT fibers to solve the grand challenge which is enhancing the performance of CNT/Cu composite fibers. Thiol groups are introduced to the surface of the CNT fibers through a controllable O2plasma carboxylation process and amide reaction. Compared with CNT/Cu composite fibers, there are 82.7% and 29.6% improvements in electrical conductivity and tensile strength of interface thiol-modification composite fibers. The enhancement mechanism is also explored that thiolated CNT fibers could make strong interactions between Cu and CNT, enhancing the electrical and mechanical performance of CNT/Cu composites. This work proposes a convenient, heat-treatment-free strategy for high-performance CNT/Cu composite fibers, which can be manufactured for large-scale production and applied to next-generation conductive wires.

Controllable etching-induced contact enhancement for high-performance carbon nanotube thin-film transistors.

Semiconducting single-walled carbon nanotubes (s-SWNTs) show great promises in advanced electronics. However, contact resistance between the nanotubes and metal electrode has long been a bottleneck to the development of s-SWNTs in high-performance electronic devices. Here we demonstrate a simple and controllable strategy for enhancing the electrode contact and therefore the performance of s-SWNT thin film transistors by plasma etching treatment, which effectively removes the polymer residues, including the photoresist and the conjugated molecules, adsorbed on the surface of s-SWNTs. As a result, the contact resistance is reduced by 3 times and the carrier mobility rises by up to 70%. Our method is compatible with current silicon semiconductor processing technology, making it a viable effective approach to large-scale application of s-SWNTs in the electronics industry.

Solution-Processing of High-Purity Semiconducting Single-Walled Carbon Nanotubes for Electronics Devices.

High-purity semiconducting single-walled carbon nanotubes (s-SWCNTs) are of paramount significance for the construction of next-generation electronics. Until now, a number of elaborate sorting and purification techniques for s-SWCNTs have been developed, among which solution-based sorting methods show unique merits in the scale production, high purity, and large-area film formation. Here, the recent progress in the solution processing of s-SWCNTs and their application in electronic devices is systematically reviewed. First, the solution-based sorting and purification of s-SWCNTs are described, and particular attention is paid to the recent advance in the conjugated polymer-based sorting strategy. Subsequently, the solution-based deposition and morphology control of a s-SWCNT thin film on a surface are introduced, which focus on the strategies for network formation and alignment of SWCNTs. Then, the recent advances in electronic devices based on s-SWCNTs are reviewed with emphasis on nanoscale s-SWCNTs' high-performance integrated circuits and s-SWCNT-based thin-film transistors (TFT) array and circuits. Lastly, the existing challenges and development trends for the s-SWCNTs and electronic devices are briefly discussed. The aim is to provide some useful information and inspiration for the sorting and purification of s-SWCNTs, as well as the construction of electronic devices with s-SWCNTs.

Effective deactivation of A549 tumor cells in vitro and in vivo by RGD-decorated chitosan-functionalized single-walled carbon nanotube loading docetaxel.

This study aims to construct and evaluate RGD-decorated chitosan (CS)-functionalized pH-responsive single-walled carbon nanotube (SWCNT) carriers using docetaxel (DTX) as a model anticancer drug. DTX was loaded onto SWCNT via π-π stacking interaction (SWCNT-DTX), followed by the non-covalent conjugation of RGD-decorated CS to SWCNT-DTX to prepare RGD-CS-SWCNT-DTX. The RGD-CS-SWCNT-DTX showed significantly higher drug release than the pure drug, giving higher release rate at pH 5.0 (68%) than pH 7.4 (49%). The RGD-CS-SWCNT-DTX could significantly inhibit the growth of A549 tumor cells in vitro, and the uptake amount of A549 cells was obviously higher than that of MCF-7 cells. Meanwhile, the cellular uptake of RGD-CS-SWCNT-DTX was higher than that of CS-SWCNT-DTX in A549 cells, mainly through clathrin and caveolae-mediated endocytosis. The RGD-CS-SWCNT-DTX significantly inhibited tumor growth of A549 cell-bearing nude mice through active tumor-targeting ability. Furthermore, no pathological changes were found in tissues and organs. The result demonstrated that RGD-CS-SWCNT-DTX displayed high drug loading, pH-responsive drug release, remarkable antitumor effect in vitro and in vivo, and also good safety to animal body.

Flexible and Lightweight Fuel Cell with High Specific Power Density.

Flexible devices have been attracting great attention recently due to their numerous advantages. But the energy densities of current energy sources are still not high enough to support flexible devices for a satisfactory length of time. Although proton exchange membrane fuel cells (PEMFCs) do have a high-energy density, traditional PEMFCs are usually too heavy, rigid, and bulky to be used in flexible devices. In this research, we successfully invented a light and flexible air-breathing PEMFC by using a new design of PEMFC and a flexible composite electrode. The flexible air-breathing PEMFC with 1 × 1 cm2 working area can be as light as 0.065 g and as thin as 0.22 mm. This new PEMFC exhibits an amazing specific volume power density as high as 5190 W L-1, which is much higher than traditional (air-breathing) PEMFCs. Also outstanding is that the flexible PEMFC retains 89.1% of its original performance after being bent 600 times, and it retains its original performance after being dropped five times from a height of 30 m. Moreover, the research has demonstrated that when stacked, the flexible PEMFCs are also useful in mobile applications such as mobile phones. Therefore, our research shows that PEMFCs can be made light, flexible, and suitable for applications in flexible devices. These innovative flexible PEMFCs may also notably advance the progress in the PEMFC field, because flexible PEMFCs can achieve high specific power density with small size, small volume, low weight, and much lower cost; they are also much easier to mass produce.

Recycling Strategy for Fabricating Low-Cost and High-Performance Carbon Nanotube TFT Devices.

High-purity semiconducting single-walled carbon nanotubes (s-SWNTs) can be obtained by conjugated polymer wrapping. However, further purification of sorted s-SWNTs and high costs of raw materials are still challenges to practical applications. It is inevitable that a lot of polymers still cover the surface of s-SWNTs after separation, and the cost of the polymer is relatively higher than that of SWNTs. Here, we demonstrated a facile isolated process to improve the quality of s-SWNT solutions and films significantly. Compared with the untreated s-SWNTs, the contact resistance between the s-SWNT and the electrode is reduced by 20 times, and the thin-film transistors show 300% enhancement of current density. In this process, most of the polymers can be recycled and reused directly without any purification, which can greatly decrease the cost for s-SWNT separation. The results presented herein demonstrate a new scalable and low-cost approach for large-scale application of s-SWNTs in the electronics industry.

Low Hysteresis Carbon Nanotube Transistors Constructed via a General Dry-Laminating Encapsulation Method on Diverse Surfaces.

Electrical hysteresis in carbon nanotube thin-film transistor (CNTTFT) due to surface adsorption of H2O/O2 is a severe obstacle for practical applications. The conventional encapsulation methods based on vacuum-deposited inorganic materials or wet-coated organic materials have some limitations. In this work, we develop a general and highly efficient dry-laminating encapsulation method to reduce the hysteresis of CNTTFTs, which may simultaneously realize the construction and encapsulation of CNTTFT. Furthermore, by virtue of dry procedure and wide compatibility of PMMA, this method is suitable for the construction of CNTTFT on diverse surface including both inorganic and organic dielectric materials. Significantly, the dry-encapsulated CNTTFT exhibits very low or even negligible hysteresis with good repeatability and air stability, which is greatly superior to the nonencapsulated and wet-encapsulated CNTTFT with spin-coated PMMA. The dry-laminating encapsulation strategy, a kind of technological innovation, resolves a significant problem of CNTTFT and therefore will be promising in facile transferring and packaging the CNT films for high-performance optoelectronic devices.

A novel strategy for high-performance transparent conductive films based on double-walled carbon nanotubes.

A high concentration of double-walled carbon nanotubes was dispersed by a carbazole-based conjugated polymer. And a transparent conductive film was fabricated via simple dip-coating using this dispersion, which showed simultaneously a low sheet resistance (average 134 Ω â–¡-1, minimal 86 Ω â–¡-1) and an ultrahigh transmittance (99% at 550 nm). This high-performance transparent conductive film has potential applications in future optoelectronic devices demanding ultrahigh transparency and flexibility.

A Mixed-Extractor Strategy for Efficient Sorting of Semiconducting Single-Walled Carbon Nanotubes.

A general strategy for sorting semiconducting single-walled carbon nanotubes (s-SWNTs) with high efficiency using a mixed-extractor is reported. When the two extractors have a sufficient difference in binding energy with s-SWNTs, and skeleton flexibility, the mixture shows enhanced yield for sorting s-SWNTs. The strategy could be effective when applied to increase the sorting yield of other selective dispersion systems.

A photodegradable hexaaza-pentacene molecule for selective dispersion of large-diameter semiconducting carbon nanotubes.

Harvesting high-purity semiconducting single-walled carbon nanotubes (s-SWCNTs) with removable dispersants remains a challenge. In this work, we demonstrate that small heteroacene derivatives may serve as promising selective dispersants for sorting s-SWCNTs. A rich N "doped" and thiophene-substituted hexaazapentacene molecule, denoted as 4HP, was found to be more favorable for high-purity s-SWCNTs with large diameters. Importantly, 4HP is photodegradable under 365 nm or blue light, which enables a simple deposition approach for the formation of clean s-SWCNT networks. The as-fabricated thin film transistors show excellent performance with a charge-mobility of 30-80 cm(2) V(-1) s(-1) and an on-off ratio of 10(4)-10(6).

Solution-Processable High-Purity Semiconducting SWCNTs for Large-Area Fabrication of High-Performance Thin-Film Transistors.

For the large-area fabrication of thin-film transistors (TFTs), a new conjugated polymer poly[9-(1-octylonoyl)-9H-carbazole-2,7-diyl] is developed to harvest ultrahigh-purity semiconducting single-walled carbon nanotubes. Combined with spectral and nanodevice characterization, the purity is estimated up to 99.9%. High density and uniform network formed by dip-coating process is liable to fabricate high-performance TFTs on a wafer-scale and the as-fabricated TFTs exhibit a high degree of uniformity.

A versatile approach to obtain a high-purity semiconducting single-walled carbon nanotube dispersion with conjugated polymers.

High-purity semiconducting single-walled carbon nanotubes (s-SWCNTs) are urgently needed in the development of beyond-silicon nanoelectronics. The utility of conjugated polymers to assist in the sorting of s-SWCNTs has attracted immense attention due to the simplicity of the sorting process and the high selectivity of conjugated polymers for s-SWCNTs. Rather than developing new types of conjugated polymers, this work provides a versatile and facile route for the sorting of s-SWCNTs with improved purity which is far beyond the sensitivity of a spectrometer.

Simple and scalable gel-based separation of metallic and semiconducting carbon nanotubes.

We report a rapid and scalable method for the separation of metallic and semiconducting single-wall carbon nanotubes (SWCNTs); the separation is performed by the selective adsorption of semiconducting SWCNTs on agarose gel. The most effective separation was realized by a simple procedure in which a piece of gel containing SWCNTs and sodium dodecyl sulfate was frozen, thawed, and squeezed. This process affords a solution containing 70% pure metallic SWCNTs and leaves a gel containing 95% pure semiconducting SWCNTs. Field-effect transistors constructed from the separated semiconducting SWCNTs have been demonstrated to function without any electrical breakdown.