Growth Of Nanotubes Research Articles

Flaky sputtered silicon MWCNTs core-shell structure as a freestanding binder-free electrode for lithium-ion battery

Core-shell silicon/multiwall carbon nanotubes are one of the most promising anode candidates for further improvement of lithium-ion batteries. Sufficient accommodation for massive volume expansion of silicon during the lithiation process and preventing pulverization and delamination with easy fabrication processes are still critical issues for practical applications. In this study, core-shell silicon/MWCNTs anode materials were synthesized using a facile and controllable PECVD technique to realize aligned MWCNTs followed by a silicon sputtering step. The use of the PECVD technique and the direct growth of multi-walled carbon nanotubes on the current collector creates a low tortuosity, flexible, and conductive scaffold, which, in addition to preventing CNT agglomeration, alleviates the pulverization and delamination of the silicon active material from the current collector, leading to the formation of an electrode with unique electrochemical performance. The CNT-Si core-shell electrode can achieve an excellent gravimetric specific capacity of 3250 mAh/g under a rate of C/5 and 99.8% capacity retention after more than 700 cycles. Electron microscopy revealed that the electrode structure has maintained its integrity and stability during long cycling (700 cycles and more). Apart from achieving high charging capacity, the use of such configuration leads to the formation of facile, inexpensive free-standing binder-free electrodes with no need to polymeric binders.

Expression of concern: In situ growth of N-doped carbon nanotubes from the products of graphitic carbon nitride etching by nickel nanoparticles.

Expression of concern for 'In situ growth of N-doped carbon nanotubes from the products of graphitic carbon nitride etching by nickel nanoparticles' by Mariusz Pietrowski et al., Nanoscale Adv., 2024, 6, 1720-1726, https://doi.org/10.1039/D3NA00983A.

In-situ growth of N-doped bamboo-like carbon nanotubes embedded with FeNi nanoparticles on carbon cloth as self-standing cathode for efficient rechargeable zinc-air battery

In-situ growth of N-doped bamboo-like carbon nanotubes embedded with FeNi nanoparticles on carbon cloth (FeNi@NBCNTs/CC) is reported and direct application of FeNi@NBCNTs/CC as self-standing bifunctional air cathodes in rechargeable zinc-air...

Synthesis of V2O3@C-CNTs nanocomposites via in situ growth of carbon nanotubes from V-MOF for enhanced lithium-sulfur battery separators

Synthesis of V2O3@C-CNTs nanocomposites via in situ growth of carbon nanotubes from V-MOF for enhanced lithium-sulfur battery separators

Reconstruction of cobalt atoms in ZIF-67 and in-situ growth of carbon nanotubes at low temperature for High-Performance strain sensors

Reconstruction of cobalt atoms in ZIF-67 and in-situ growth of carbon nanotubes at low temperature for High-Performance strain sensors

Statistical Investigation of Factors Affecting the Growth of Carbon Nanotubes in the Chemical Vapor Deposition (CVD) Processes

Statistical Investigation of Factors Affecting the Growth of Carbon Nanotubes in the Chemical Vapor Deposition (CVD) Processes

Engineering Asymmetric Bimetallic CoM (M = Ni, Fe, Mn, Cu) Nanoparticles Encapsulated in Freestanding Wood-Derived Carbon Electrodes for Enhanced ORR Kinetics in Zinc-Air Batteries.

The electrochemical reduction of oxygen is pivotal for advancing emerging energy technologies. Precise control over morphology and electronic structure is essential for enhancing catalytic activity and stability in the oxygen reduction reaction (ORR). In this study, a freestanding carbon electrode is developed by in-situ growth of carbon nanotube (CNT)-encapsulated bimetallic CoM (M = Ni, Fe, Mn, Cu) nanoparticles (NPs) within a hierarchical carbonized wood matrix (CoM@NWCC). The hierarchically porous architecture of the electrode promotes efficient mass transfer during the ORR. X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) analyses revealed that incorporating metals such as Ni, Fe, Mn, and Cu modulates the electronic structure of Co, specifically adjusting the distance between the d-band center (Ed) and the Fermi level (EF), thus optimizing ORR kinetics. Among these, CoNi@NWCC, with its asymmetric electronic configuration, achieves an optimal balance between OH* and OOH* adsorption, significantly enhancing catalytic performance. This study demonstrates the potential of band structure engineering to precisely tailor catalyst properties, offering a cost-effective and high-performance solution for zinc-air batteries (ZABs) suitable for large-scale deployment.

Preparation of Single‐Crystal MoS2 Nanotubes and 1D Van der Waals Heterostructures

AbstractSingle‐crystal MoS2 nanotubes possess outstanding electronic and optoelectronic properties. However, previous attempts to synthesize MoS2 nanotubes are hindered by poor crystallinity and the high strain energy required to roll a sheet with three atomic layers into a tubular structure. Here, the confined template growth of well‐crystallized MoS2 nanotubes encapsulated within carbon nanotubes, forming 1D van der Waals heterostructures, is reported. The growth of MoS2 nanotubes is catalyzed by iron carbide. CNTs serve as nanoreactors and structurally confined templates, ensuring the growth of fine MoS2 nanotubes. Water vapor is employed to manipulate the structure and morphology of resultant MoS2. Free‐standing MoS2 nanotubes are obtained by removing outer CNTs with gentle plasma etching. This method demonstrate the power of coupling the catalytic effect and the space confinement in the growth of high‐quality MoS2 nanotubes, which may become a common strategy for the preparation of general 1D nanostructures of various transition metal dichalcogenides and other materials.

Controlled carbon nanotube growth with hydrocarbon nanobelt templates

Controlled carbon nanotube growth with hydrocarbon nanobelt templates

Effect of Chemical Polishing on the Formation of TiO2 Nanotube Arrays Using Ti Mesh as a Raw Material.

As a unique form of TiO2, TiO2 nanotube arrays (TiO2NTAs) have been widely used. TiO2NTAs are usually prepared by Ti foil, with little research reporting its preparation by Ti mesh. In this paper, TiO2NTAs are prepared on a Ti mesh surface via an anodic oxidation method in the F-containing electrolyte. The optimal parameters for the synthesis of TiO2NTAs are as follows: the solvent is ethylene glycol and water; the electrolyte is NH4F (0.175 mol/L); the voltage is 20 V; and the anodic oxidation time is 40 min without chemical polishing. However, there is a strange phenomenon where the nanotube arrays grow only at the intersection of Ti wires, which may be caused by chemical polishing, and the other areas, where TiO2NTAs cannot be observed on the surface of Ti mesh, are covered by a dense TiO2 film. New impurities (the hydrate of TiO2 or other products) introduced by chemical polishing and attaching to the surface of the Ti mesh reduce the current of anodic oxidation and further inhibit the growth of TiO2 nanotubes. Hence, under laboratory conditions, for commercially well-preserved Ti mesh, there is no necessity for chemical polishing. The formation of TiO2NTAs includes growth and crystallization processes. For the growth process, F- ions corrode the dense TiO2 film on the surface of Ti mesh to form soluble complexes ([TiF6]2-), and the tiny pores remain on the surface of Ti mesh. Given the basic photoelectrochemical measurements, TiO2NTAs without chemical polishing have better properties.

In situ catalyzed growth of carbon nanotube with asphalt cladding as a bicarbon synergistic framework of silicon anodes for lithium-ion batteries.

Silicon, as the most promising advanced anode material for lithium-ion batteries, faces challenges in large-scale industrial production due to the significant volume expansion effect. In this investigation, Si/CNTs/C composite materials were effectively produced through high-temperature carbonization utilizing asphalt, silicon, hexahydrate ferric chloride, and melamine as primary elements. The distinctive dual-carbon framework of asphalt-derived carbon and carbon nanotubes alleviates the volume expansion of silicon, thereby stabilizing the composite material's structure. Testing the electrochemical performance reveals that the Si/CNTs/C composite material exhibits a reversible specific capacity of 1187 mAh g-1 with a capacity retention rate of 92.6% after 150 cycles at a current density of 0.2 A g-1. Even after 500 cycles at a current density of 1 A g-1, it sustains a specific capacity of 879.4 mAh g-1 with a capacity retention rate of 87.9%, showcasing outstanding electrochemical performance.

Comparative Analysis of Anodized TiO2 Nanotubes and Hydrothermally Synthesized TiO2 Nanotubes: Morphological, Structural, and Photoelectrochemical Properties.

This study presents a comparative analysis of anodization and hydrothermal techniques for synthesizing TiO2 nanotubes directly on titanium foil. It emphasizes its advantages as a substrate due to its superior conductivity and efficient charge transfer. Optimized synthesis conditions enable a thorough evaluation of the resulting nanotubes' morphology, structure, and optical properties, ultimately assessing their photoelectrochemical and photocatalytic performances. Scanning electron microscopy (SEM) reveals differences in tube diameter and organization. An X-ray diffraction (XRD) analysis shows a dominant anatase (101) crystal phase in both methods, with the hydrothermally synthesized nanotubes exhibiting a biphase structure after annealing at 500 °C. UV-Vis and photoluminescence analyses indicate slight variations in band gaps (around 0.02 eV) and recombination rates. The anodized TiO2 nanotubes, exhibiting superior hydrophilicity and order, demonstrate significantly enhanced photocatalytic degradation of a model pollutant, amido black (80 vs. 78%), and achieve a 0.1% higher photoconversion efficiency compared to the hydrothermally synthesized tubes. This study underscores the potential advantages of the anodization method for photocatalytic applications, particularly by demonstrating the efficacy of direct TiO2 nanotube growth on titanium foil for efficient photocatalysis.

CO2 plasma inducing steel-slag with active sites for efficient growth of carbon nanotubes for the high-performance microwave absorption

As a solid waste generated in the metallurgical process, the highly efficient catalysis of steel-slag for carbon nanotube (CNT) growth remains a huge challenge. Herein, a CO2 plasma-inducing approach for modifying the steel-slag catalyst with rich active sites was developed for CNT growth in the chemical vapor deposition (CVD) process. Furthermore, the high-energy CO2 plasma refines the particles on the steel-slag surface, reducing the particle size on the surface of steel-slag effectively increasing the active sites of the catalyst. In addition, the thermal effect generated by the gas molecule ionization process under CO2 increases the background temperature of the steel-slag, and the interaction between the oxygen-active substances produced and the iron oxide on the surface of steel-slag undergoes an oxidation reaction upon full contact with high-energy particles, which greatly improves the catalytic efficiency of the steel-slag as a catalyst for CNT, and increases the catalytic efficiency by 50 % compared with the non-plasma modified steel-slag as a catalyst for catalyzing CNTs. In addition, catalytically grown CNTs encapsulate magnetic steel-slag catalysts to form a three-dimensional CNT network structure, with high-performance electromagnetic wave absorption. The composite absorbing material with a thickness of only 3.55 mm has a minimum absorption rate of −64.08 dB for electromagnetic waves at a frequency of 7.9 GHz. The dielectric and the magnetic loss of steel-slag lead to enhanced electromagnetic wave absorption. Therefore, this study provides an inexpensive and environmentally friendly idea for the design of high-efficiency CNT growth and solid waste catalyst modification synthesized with high-performance absorbers.

Lithium Demand and Cyclability Trade‐Off in Conductive Nanostructure Scaffolds in Terms of Different Tortuosity Parameters

AbstractThrough alteration of the polarity of DC plasma during the growth of carbon nanotubes in a PECVD reactor, significantly different morphologies of such species have been achieved. By using this approach, for the first time, both Half‐aligned and Entangled structures were synthesized, along with Full‐aligned carbon nanotubes, introducing three binder‐free electrodes with various levels of tortuosity. The crucial parameter and influential effect of tortuosity in these three‐dimensional nanostructure scaffolds for application in lithium‐ion batteries were investigated. Previous research findings suggested that increasing the tortuosity of the conductive scaffolds leads to preferential accumulation of lithium at the top surface and causes the loss of capacity in subsequent charge‐discharge cycles. Our finding reveals that there exists a trade‐off between lithium‐demand, capacity, and preferential accumulation of lithium at the top surface. Among the presented scaffolds, the Half‐aligned MWCNTs was able to maintain a high capacity of 876.9 mAh/g over more than 300 cycles, and demonstrate capacity improvement during this period and excellent rate capability, even at a rate of 5 C. This capacity is almost three times that can be achieved with graphite, showcasing promising and outstanding results for carbon nanotubes.

Electrochemical characterization of TiO2 nanotubes formed on Ti6Al4V manufactured by PBF-EB or forging

AbstractThis study introduces the anisotropy effect of Ti6Al4V substrate obtained by electron beam melting (PBF-EB) on the anodizing process, revealing its capacity to induce anisotropic TiO2 nanotubes. Highly organized TiO2 nanotubes are formed on Ti6Al4V substrates produced through PBF-EB or forging, with the PBF-EB cross-orientation displaying superior nanotube growth due to enhanced catalytic activity. Morphological and electrochemical characterizations underscore the significant influence of substrate orientation and anodizing voltage on nanotube growth and corrosion resistance. PBF-EB-cross orientation at 30 V exhibits a thicker and more homogeneous nanotube layer, resulting in improved film resistance and substantially lower corrosion rates compared to forged substrates. The electrochemically calculated nanotube film thickness aligns with microscopic analyses, emphasizing the importance of a homogenous and resistive nanotube coating for effective corrosion control.

Flow characteristics in a horizontal reactor for continuous preparation of carbon nanotubes

This study focuses on a sophisticated horizontal reactor designed to facilitate the continuous growth of carbon nanotubes (CNTs) through chemical vapor deposition (CVD). Experimental observations reveal that carbon production varies at different locations within the reactor, with higher yields typically found in the middle and rear zones. The flow dynamics within the reactor play a pivotal role in CNT growth, prompting a detailed simulation of the flow field using Computational Fluid Dynamics (CFD). This simulation leverages fluid dynamics principles to assess the impact of various parameters on the flow field, ultimately identifying the optimal operating conditions. Findings indicate that temperature-induced density contrasts create cyclic flow patterns that can negatively affect CNT growth rates. However, the gas flow inside the horizontal continuous preparation reactor can be improved and optimized by adjusting and controlling the preparation parameters. Appropriately lowering the heating temperature and the mole fraction of propylene in inlet 2, within the range of conditions suitable for the growth of CNTs, while minimizing the perturbation of the flow field by the shape of the carriers, can promote more favorable CNTs growth.

Enhancing Zinc-Air Flow Batteries: Single-Atom Catalysis within Cobalt-Encapsulated Carbon Nanotubes for Superior Efficiency.

Amid the world's escalating energy needs, rechargeable zinc-air batteries stand out because of their environmental sustainability, with their performance being critically dependent on the oxygen reduction reaction (ORR). The inherent slow kinetics of the ORR at air electrodes frequently constrains their operational efficiency. Here, we develop a new self-catalytic approach for in situ growth of carbon nanotubes with new cathode material Co@CoN3/CNTs-800 without external additives. Density functional theory calculation reveals this method integrates nonprecious single-atom catalysis with spatial confinement, facilitating large-scale, in situ fabrication of CNTs, which can support dispersed atomic CoN3 sites and enforce spatial confinement on Co nanoparticles. The Co@CoN3/CNTs-800 electrode achieves an electron transfer number close to ideal (3.9 out of 4.0). In rechargeable zinc-air flow batteries, it achieves a peak power density of 169.5 mW cm-2 and a voltage gap that is only 1.6% larger than the original after 700 h. This work surmounts critical challenges in the ORR kinetics for zinc-air batteries.

Influence of anodically grown TiO2 nanotubes on shear strength and fatigue behavior of pure titanium

Titanium and its alloys are among the best materials for metallic biomedical implants owing to their well-established biocompatibility. The effects of surface conditions on the success of implant osseointegration have been investigated previously. Although yet to be applied in clinical practice, the anodic growth of TiO2 nanotubes on implant surfaces has been reported to enhance biocompatibility. However, such a coating increases the roughness of the surface, which can adversely affect the fatigue strength. The cyclical loading mode supported by most bone implants necessitates investigations into the effect of nanostructured coatings on the fatigue life of the implants. This study evaluates the rotating-beam fatigue strength (Fatigue stress ratio = −1, Number of cycles = 107 cycles) of pure titanium specimens coated with TiO2 nanotubes. TiO2 nanotubes are grown via anodization in an HF (0.1% vol.) aqueous solution by applying 20 V for 2 h, thus resulting in nanotubes with diameters and lengths of approximately 100 and 500 nm, respectively. The TiO2 coating, which is initially amorphous, is crystallized via thermal treatment at 370 °C for 3 h, thus resulting in an anatase allotrope, which has been reported to provide better conditions for the integration between the implant and bone. Results of adhesion tests show that the nanotube coating adheres well to the substrate surface and that its integrity is unaffected during fatigue tests. Meanwhile, results of fatigue tests show the insignificant effect of the TiO2 nanotubes on fatigue strength, which indicates that this coating can be used without compromising the implant fatigue life.

Boosting oxygen reduction performance by copper-iron co-doped on ZIF-derived N-doped carbon nanotubes

Developing high-efficiency non-noble metal catalysts for the oxygen reduction reaction (ORR) is paramount for sustainable energy conversion. In this study, we proposed a Cu, Fe co-doped zeolite imidazole framework (ZIF)-derived nitrogen-doped carbon nanotubes catalyst (Cu–Fe@CNTs/NC) obtained by hydrothermal method and pyrolysis. The electrochemical results showed that Cu–Fe@CNTs/NC exhibited favorable oxygen reduction performance and good stability under alkaline electrolyte. The incorporation of Cu and Fe bimetallic dopants promoted the carbon nanotubes growth on ZIF nanosheets, and the collaborative action of Cu and Fe enhanced its ORR catalytic activity. These findings provide an innovative way to prepare high active non-platinum ORR catalysts.

Critical plasma-processing-enabled growth of chirality-predefined single-walled carbon nanotubes from carbon nanorings

The chirality-controlled growth of single-walled carbon nanotubes (SWNTs) has been an ultimate challenge since their discovery. We report a proof-of-principle plasma processing on the chirality-predefined growth of SWNTs originating from single-hoop molecules of carbon six-membered rings (carbon nanorings: CNRs), which can be viewed as simple units of (n, n) metallic SWNTs (n: the number of benzene rings). Plasma-enhanced chemical vapor deposition enables us to find the correlation between the diameter of CNRs and that of SWNTs over n = 6–12, while only the specified CNRs (n = 10, 12) correspondingly grow up to near (10,10) and (12,12) metallic SWNTs at critical low-temperature of 350 °C.