Carbon Nanotubes Research Articles

Enhancing Thermoelectric Properties of Strontium Titanate Through In situ Growth of Carbon Nanotubes.

Integrating low-dimensional materials, such as carbon nanotubes (CNTs), into thermoelectric matrices offers a promising route to enhance performance, yet achieving uniform dispersion and optimal interfacial properties remains a key challenge. In this study, a novel approach is demonstrated to boost the thermoelectric properties of strontium titanate (SrTiO3) through the in situ growth of CNTs via chemical vapor deposition (CVD). By meticulously tuning catalyst composition, growth temperature, and catalyst concentration, the morphology and distribution of CNTs are optimized, ensuring homogeneous integration within SrTiO3 matrix. Theoretical calculations show that Ni/SrTiO3 compounds have an energy barrier of 0.41eV for CH4 dissociation into carbon atoms, much lower than that of Fe (100), Co (100), and Ni (100), thus facilitating CNT growth. Experimental results show that the 0.1-Ni sample improves electrical conductivity by ≈69% at room temperature, outperforming samples prepared by conventional mechanical mixing. Furthermore, the incorporation of in situ grown CNTs substantially reduces thermal conductivity by intensifying interfacial phonon scattering, achieving a thermoelectric figure of merit (zT) of 0.3 at 1000 K. These synergistic effects between enhanced electrical conductivity and reduced thermal conductivity establish a robust pathway for embedding low-dimensional carbon nanostructures into oxide thermoelectric materials, paving the way for next-generation high-performance thermoelectric composites.

Low-coordination water in COFs and acid-free proton conduction.

In this study, a covalent organic framework (COF) membrane has been synthesized, featuring one-dimensional channels akin to those of carbon nanotubes (CNTs), yet boasting enhanced crystallinity and electrical insulation properties. It exhibits remarkable acid-free proton conduction in aqueous environments, which is attributed to the orientation distribution and low coordination number of water molecules in the confined space.

Rapid Detection of Perfluorodecanoic Acid and Perfluorooctanesulfonic Acid in Foods Using a Molecularly Imprinted Poly(o-phenylenediamine)/Modified Glassy Carbon Electrode.

In the current work, a modified glassy carbon electrode (GCE) with excellent conductivity was prepared by drop-coating carboxymethyl cellulose (CMC) and multiwalled carbon nanotubes (MWCNTs) on the GCE surface. On this basis, two highly selective molecularly imprinted sensors (MIP@PFDA/modified GCE and MIP@PFOS/modified GCE) were separately obtained by in situ electropolymerization of o-phenylenediamine (o-PD) with perfluorodecanoic acid (PFDA) and perfluorooctanesulfonic acid (PFOS) as templates. Under optimal conditions, sensitive quantification methods in the linearity ranges 0.1-1000 ng/mL (PFDA) and 0.05-900 ng/mL (PFOS) were developed via differential pulse voltammetry using [Fe(CN)6]3-/4- as a redox probe. The detection limit values of PFDA and PFOS were as low as 0.041 and 0.015 ng/mL, respectively. Both sensors also presented great stability and selectivity in coexistence with other interferences. Lastly, three food samples were utilized to verify the validity and applicability with recoveries of 89.97%-112.27%, confirming its potential for per- and polyfluoroalkyl substances (PFASs) monitoring in a complex matrix.

Intrinsic strain of defect sites steering chlorination reaction for water purification

Carbon nanotube (CNT)–based heterogeneous advanced oxidation processes (AOPs) used for water purification have been exploited for several decades. Many strategies for modifying CNTs have been utilized to improve their catalytic performance in remediation processes. However, the strain fields of the intrinsic defect sites on CNT steering AOPs (such as chlorination) have not yet been reported. Here, we explored the strained defect sites for steering the chlorination process for water purification. The strained defect sites with the elongated sp2 hybridized C–C bonds boost electronic reactivity with the chlorine molecules via the initial Yeager–type adsorption. As a result, the reactive species in chlorination can be regulated on demand, such as the ratio of high–selectivity ClO• ranging from 38.8% in conventional defect–based systems to 87.5% in our strain–dominated process, which results in the generation of harmless intermediates and even deep mineralization during 2,4–DCP abatement. This work highlights the role that strain fields have on controlling the extent of chlorination reactions.

Overcoming Ambient Drift and Negative-Bias Temperature Instability in Foundry Carbon Nanotube Transistors.

Carbon nanotube field-effect transistors (CNFETs) are promising candidates for back-end-of-line logic integration as a complementary path for continued electronic scaling. However, overcoming CNFET ambient drift (i.e., air stability) and reliability is underexplored. Here, we demonstrate that silicon nitride encapsulation limits ambient atmosphere-induced threshold voltage shift (∼8× reduction of median ΔVT over 90 days). With stabilized nitride-encapsulated CNFETs, we characterize CNFET negative bias temperature instability (NBTI) with both DC and AC stress across the electric field, temperature, gate oxide thickness, and stress frequency. AC pulsed operation significantly improves CNFET NBTI vs DC operation across a wide frequency range of 1 kHz-10 MHz. A 20% duty cycle AC operation at 10 MHz could extend the NBTI time to failure by > 104× vs DC for a target |ΔVT| tolerance ≤100 mV with a gate bias VGS,Stress = -1.2 V at 125 °C. This work improves our understanding of overcoming ambient drift and BTI reliability in CNFETs.

Atomic and Electronic Structures of 1D Phosphorus Nanoring and Nanohelix.

Elemental phosphorus, with its diverse polymorphs, presents intriguing opportunities for material design owing to its ability to stabilize in various allotropes. In this work, we investigate the one-dimensional (1D) phosphorus nanoring and nanohelix structure. 1D phosphorus allotropes are stabilized within the carbon nanotubes (CNTs) that act as nano reaction vessels. Transmission electron microscopy (TEM) imaging provides experimental evidence for the formation of nanoring and nanohelix structures. First-principles calculations show distinct orbital characters between valence and conduction bands and reveal strain-induced valence band reordering. Our findings provide a foundation for further studies into topological and optical properties of 1D phosphorus nanostructures.

The Role and Future of Functional Graphenic Materials in Biomedical and Human Health Applications.

Functional graphenic materials (FGMs) are materials derived from graphene oxide (GO) that hold a plethora of applications from electronics to nanomedicine. In this Perspective, we examine the history and evolution of biomedical applications of this carbon-based macromolecule. Following the carbon nanotube (CNT) movement, GO and FGMs became nanocarbons of interest because of their low cost and versatile functionality. The tunable chemistry enabled our work on FGMs coupled with biomacromolecules and allows FGMs to plays an important role in many biomedical applications, from tissue regeneration to controlled delivery. As we work to develop this material, it is critical to consider toxicity implications─in fresh materials as well as in degradation products. With this understanding, FGMs also hold potential roles in human health and environmental sustainability, making FGMs an important contemporary biomacromolecule.

Siglec-14-Mediated Inflammatory Responses to Carbon Nanomaterials.

Carbon nanomaterials (CNM), including carbon nanotubes (CNT) and graphene nanoplatelets (GNP), are expected to have diverse industrial applications due to their unique physical properties. However, concerns have been raised regarding their toxicity in humans. In this context, risk assessment must include an understanding of the molecular mechanisms underlying human recognition of CNM. We have recently identified human sialic acid-binding immunoglobulin-like lectin (Siglec)-14 as a CNT-recognizing receptor. Since no rodent orthologs for Siglec-14 exist, previous rodent toxicological studies may underestimate CNM toxicity in humans. Therefore, in this study, we investigate Siglec-14 responses to various CNM. Siglec-14 recognizes various types of CNM via its extracellular aromatic cluster with a similar affinity, regardless of size and shape. Ultrathin single-walled CNT (SWCNT) and spherical carbon black nanoparticles (CBNP) activated macrophage Siglec-14 signaling, leading to IL-8 production. Notably, GNP as well as long needle-like MWCNT not only activate this inflammatory signal but also cause phagosomal damage, leading to the release of IL-1β, the most prominent pro-inflammatory cytokine. In mice transduced with Siglec-14, intratracheal injection of GNP or long needle-like MWCNT caused lung inflammation, whereas injection of SWCNT or CBNP did not. Taken together, these results suggest that CNM-induced inflammation requires two processes: macrophage receptor ligation and phagosomal damage. This indicates that CNM may be safe unless they cause damage to the macrophage phagosome.

Comprehensive Investigation into the Thermal Performance of Nanofluid-Enhanced Heat Pipes for Advanced Thermal Management Systems

This study investigates the thermal performance of heat pipes using nanofluids based on silver (Ag), aluminum oxide (Al2O3), and multi-walled carbon nanotubes (MWCNTs) at varying concentrations. Heat pipes, recognized for their efficiency in passive thermal management, face limitations with traditional fluids. Nanofluids, engineered by dispersing nanoparticles in base fluids, were explored as alternatives due to their superior thermal conductivity and convective properties. Nanofluids were prepared using ultrasonication, and their thermal conductivity, viscosity, and stability were evaluated. Experimental tests were conducted under controlled conditions to assess the impact of nanoparticle type, concentration, inclination angle, and fluid filling ratio on performance metrics, including thermal resistance (TR) and heat transfer coefficients (HTCs). The results demonstrated that Ag-based nanofluids outperformed others, achieving a 150% increase in thermal conductivity and an 83% reduction in TR compared to deionized water. HTCs increased by 300% for Ag nanofluids at a 0.5% concentration. Inclination angles and filling ratios also significantly affected performance, with optimal conditions identified at a 70% filling ratio and a 30° inclination angle. The findings highlight the potential of nanofluids in optimizing heat transfer systems and provide a framework for selecting suitable parameters in industrial applications.

Size effect of carbon nanotubes confined CoP–Ni2P heterostructure via phosphorylation-induction strategy for efficient overall water splitting

Size effect of carbon nanotubes confined CoP–Ni2P heterostructure via phosphorylation-induction strategy for efficient overall water splitting

Magnetic N-doped CNT stabilized Cu2O as a catalyst for N-arylation of nitriles and aryl halides in a biocompatible deep eutectic solvent.

This study documented the hydrolysis of nitriles by copper(i) oxide immobilized on nitrogen-doped carbon nanotubes (N-CNT/Fe3O4-Cu2O) to yield corresponding amides in the presence of a deep eutectic solvent (ChOH/Gly). Furthermore, the aforementioned catalyst can facilitate the coupling reaction between aryl halides and amides derived by nitrile hydrolysis. Consequently, the integration of two copper-catalyzed processes can efficiently provide N-aryl amides. Choline hydroxide in a deep eutectic solvent serves as a cost-effective organic catalyst in nitrie hydrolysis by forming hydrogen bonds with nitrile, thereby activating it. The catalyst generated higher to satisfactory product yields. One of the special benefits of the catalyst is that it can be restored through the addition of an external magnetic field.

Identification and Analysis of Two Critical Structural Parameters Governing the Strength of Carbon Nanotube Fibers.

Despite significant advancements in theoretical and experimental research, the strength of state-of-the-art carbon nanotube fibers (CNTFs) still falls short of their theoretical limits. To bridge this gap, a detailed understanding of the structure-strength relationships of CNTFs is urgently needed to guide enhancement of the fiber strength. In this work, a mesoscale quantitative model employing coarse-grained molecular dynamics simulations was proposed to investigate the relationship between the conformation of CNTFs and fiber strength. Two structural features were identified to affect the overall fiber strength by machine learning: the length-pore ratio (α) and porosity (β). An in-depth analysis of various postprocessing techniques reveals that the objective of process optimization is to maximize α while simultaneously minimizing β. When these two factors are fine-tuned, it is possible to significantly enhance the mechanical performance of CNTFs, bringing their strength closer to the theoretical predictions.

Enhanced Thermoelectric Performance in Cu7Sn3S10‐based Hybrid Materials with Highly Dispersed Multiwalled Carbon Nanotubes

AbstractTernary copper chalcogenide Cu7Sn3S10 has attracted great attention due to its complex and tunable crystal structure, good thermoelectric performance, and earth‐abundant and eco‐friendly elements. However, the optimization of thermoelectric performance in Cu7Sn3S10 is greatly restricted because the strategy of element doping to tune electrical and thermal transports is only limited by halogen elements. Here, highly dispersed multiwalled carbon nanotubes (MCNTs) are introduced into Cu7Sn3S10 to realize hybrid materials with enhanced thermoelectric performance. A series of Cu7+ySn3S10/x wt.% MCNTs hybrid materials are successfully fabricated by ball milling combined with spark plasma sintering. The high‐purity Cu7Sn3S10/MCNTs hybrid materials are identified as polymorphs simultaneously crystalizing in tetragonal, primitive cubic, and face‐centered cubic structures. Such complex phase structures can produce lots of intrinsic cation‐disorders, phase interfaces, grain boundaries, and Cu7Sn3S10/MCNTs heterointerfaces, which can strengthen phonon and carrier scattering, while the heterointerfaces can serve as carrier reservoirs to trap holes to reduce the carrier concentration toward the optimal range. Combining these effects, both lattice thermal conductivity and carrier thermal conductivity are significantly reduced. Correspondingly, a maximum figure of merit zT of 0.65 is achieved in Cu7.05Sn3S10/2wt.% MCNTs at 750 K, about twice as compared with the MCNTs‐free Cu7Sn3S10. This work suggests that hybrid materials with well dispersed MCNTs can greatly enhance the material's thermoelectric performance.

Graphitic Nature Governs CO2 Hydrogenation Reactions on Platinum@Carbon Nanocomposites

In this study, we discuss the influence of carbon support on the performance of platinum nanoparticles (Pt-NPs) in gas-phase CO2 hydrogenation towards industrially demanding CO production. To this end, Pt-supported on graphite oxide, carboHIPE, activated carbon, multiwalled carbon nanotubes (MWCNT), and graphite of different specific surface areas and degree of graphitization were synthesized with identical loading per unit surface area (25 µg Pt/m2 of support) to reveal the contribution of the carbon support. All Pt@carbon nanocomposites were selective to CO at temperatures above 800 K, however, we found an additional correlation between their catalytic performance and the degree of graphitization of the support. Graphite-supported platinum (Pt@Graphite) has the highest TOF and the lowest activation energy among the studied nanocomposites due to the increasing electron donation from the carbon support to the Pt nanoparticles, which facilitates CO2 adsorption on Pt by shifting its d-band centre towards the Fermi level. Our study shows that beside surface area, porosity, thermal stability, a further parameter needs to be taken into consideration, as the Pt/C interface has significant effect at the atomic level on the activity of carbon-supported catalysts in gas-phase CO2 hydrogenation towards CO production.Graphical

Engineering properties and acoustic emission response of nanocomposite foam concrete

Carbon nanotube foam concrete (CNFC) is a low-carbon and sustainable lightweight backfill material. In this paper, the cracking evolution characteristics and the damage patterns of CNFC during uniaxial compression were monitored by the acoustic emission (AE) technique, and the microscopic pore structure of CNFC was analyzed by fractal theory. The results demonstrated that the flowability of CNFC was within 163–176 mm, respectively. With 0.05 wt.% carbon nanotubes (CNT), the 7d and 28d compressive strengths of foam concrete (FC) increased by 33.04% and 27.74%, respectively. The microstructural observation revealed that CNT can improve foam stability and optimize the pore spatial distribution and size. The AE responses reflected the excellent bridging effect of CNT effectively suppressed the crack development during compression and enhanced the performance of FC. CNT increased the cost of CNFC from 169.78 RMB/m 3 to 423.72 RMB/m 3 . The cost per unit of intensity of CNFC0.05 increased by 17.44% and the CO 2 emission per unit of intensity decreased by 21.69%. The results are expected to provide a reference for the preparation and research of nanocomposite foam concrete.

Nanoarchitectonics of Palladium Nanoparticles Supported on Carbon‐Based Heterogeneous Catalysts for C─H Activation Reaction

AbstractOrganic reactions involving the direct functionalization of non‐activated C─H bonds represent a valuable class of transformations, enhancing atom, and step economy while streamlining chemical synthesis. However, the high stability of C─H bonds often necessitate harsh reaction conditions, significantly limiting their application in synthesizing complex organic molecules. In order to break the inert C─H bond and convert it into the useful C─C, C─O, C─X, and C─N conversion under benign conditions, several active and selective catalytic systems have been designed. Metal (Pd)‐supported carbon‐based heterogeneous catalysts offer a promising approach in this context. Different type of support such as graphene oxide, reduced graphene oxide and carbon nanotubes are used as a support material. Pd(II) species activates the C─H bond, and involved in an oxidation and reduction cycle involving insertion to the substrate and regeneration of catalytic active site. The activation of C─H bonds in hydrocarbons involves the insertion of a metal into the C─H bond resulting in the formation of an organometallic complex which then reacts with another substrate (reaction partner) to yield the final product. Sometime the efficiency of Pd metal can be increased by using another metal which helps to reduce the HOMO–LUMO gap and stabilize the catalyst. Therefore, this minireview discuss the most recent advancement of Pd supported on carbon based heterogeneous catalyst for C─H bond activation.

3D-Printed Nanocarbon Polymer Conductive Structures for Electromagnetic Interference Shielding.

Electromagnetic interference (EMI) significantly affects the performance and reliability of electronic devices. Although current metallic shielding materials are effective, they have drawbacks such as high density, limited flexibility, and poor corrosion resistance that limit their wider application in modern electronics. This study investigates the EMI shielding properties of 3D-printed conductive structures made from polylactic acid (PLA) infused with 0D carbon black (CB) and 1D carbon nanotube (CNT) fillers. This study demonstrates that CNT/PLA composites exhibit superior EMI shielding effectiveness (SE), achieving 43dB at 10GHz, compared to 22dB for CB/PLA structures. Further, conductive coating of polyaniline (PANI) electrodeposition onto the CNT/PLA structures improves the SE to 54.5dB at 10GHz. This strategy allows fine control of PANI loading and relevant tuning of SE. Additionally, the 3D-printed PLA-based composites offer several advantages, including lightweight construction and enhanced corrosion resistance, positioning them as a sustainable alternative to traditional metal-based EMI shielding materials. These findings indicate that the SE of 3D-printed materials can be substantially improved through low-cost and straightforward PANI electrodeposition, enabling the production of customized EMI shielding materials with enhanced performance. This novel fabrication method offers promising potential for developing advanced shielding solutions in electronic devices.

Photo/Electro‐Thermal Superhydrophobic Wood with Phase Change Materials for Highly Efficient Anti‐/Deicing

AbstractSuperhydrophobic surfaces integrating photo‐thermal and electro‐thermal have been regarded as one of the most promising anti‐/deicing approaches in all‐weather conditions. However, excessive energy consumption remains a significant obstacle to their development. Bioinspired by the energy storage and conversion functions of creatures surviving in extremely cold environments, the naturally anisotropic porous wood is performed as a substrate and a photo/electro‐thermal superhydrophobic phase change wood with highly efficient anti‐/deicing performance is developed. The abundant and unique anisotropic wood channels coated with polypyrrole (PPy) nanoparticles, combining with phase change materials (PCMs), results in superior energy conversion performance in the longitudinal channels and increased loading capacity for PCMs. Meanwhile, the superhydrophobic carbon nanotubes (CNT) coatings endow wood with excellent encapsulation and durable stability. Owing to the photo/electro‐thermal efficiency up to 91.1% and 96.7% under low‐temperature conditions, the photo/electro‐thermal superhydrophobic phase change wood exhibits high‐performance anti‐/deicing for application in wooden building roofs. This strategy offers potential toward developing sustainable, all‐weather and highly efficient anti‐/deicing.

First Encapsulation of Organometallic Single-Molecule Magnet into Single-Walled Carbon Nanotubes.

An air-sensitive DyCp3 (Cp- = cyclopentadienyl) single-molecule magnet (SMM) complex (1) was encapsulated into single-walled carbon nanotubes (SWCNTs) to construct hybrid materials that are resistant to moisture and oxygen. The hybrid materials with independent slow-magnetic-relaxing centers are expected to become a key component of the next generation of information process devices based on spintronics. The resilience to moisture and oxygen further broadens its manufacturing methods and application scenarios. Furthermore, upon encapsulation into SWCNTs, DyCp3 exhibited clear ac frequency dependence in the ac magnetic susceptibility at a zero-dc field. This indicates that the guest molecule's slow magnetic relaxation properties are preserved, which is crucial and necessary to realize SMMs-based quantum information processing, by allowing a sufficient time window for quantum gate operations. Our result exemplifies that encapsulation of air-sensitive organometallic SMMs into SWCNTs enhances their chemical stability and their magnetic relaxation time at a zero-dc magnetic field, which provides a novel method for their further applications.

Mo2C Supported by Oxidized Carbon Nanotubes for Reinforcing Epoxy Composite

Mo₂C Supported by Oxidized Carbon Nanotubes for Reinforcing Epoxy Composite