Bamboo-like Nanotubes Research Articles

Microstructure evolution and high-temperature oxidation behavior of low-carbon MgO-C refractories with TiB2 addition

Combining the advantages of both containing-B compounds and containing-Ti compounds, a new TiB2 addition is proposed in MgO-C refractories. In this paper, the high-temperature oxidation behavior of low-carbon MgO-C refractories with TiB2 addition was investigated, especially the effect of microstructure and phase evolution on the high-temperature oxidation behavior was discussed. The results show that in the materials, TiB2 preferentially reacts with oxygen, forming TiCxN1-x, Mg3(BO3)2 and Mg2TiO4 ceramic phases, and catalyzing the decomposition of phenolic resin to form bamboo-like nanotubes and carbon nanospheres to bond aggregates and fill pores. Meanwhile, TiB2 also promotes the formation of regenerated MgO compact zone, hindering the diffusion of oxygen into the materials to improve the oxidation resistance. Compared with the blank control specimen and the specimen with B4C addition, the oxidation resistance increased by 243.4 % and 79.2 %, respectively.

Polyolefin-derived substrate-grown carbon nanotubes as binder-free electrode for hydrogen evolution in alkaline media

Switching from a linear mode of waste management to a circular loop by transforming plastic waste into carbon nanotubes (CNTs) is a promising approach to current plastic waste treatment. One of the many applications of CNTs is its use for electrocatalytic water splitting for hydrogen evolution. Existing methods of CNTs-based hydrogen evolution reaction (HER) electrode fabrication involve additives like polymeric binders and additional steps to improve CNT dispersion, which are detrimental to the CNT structure and properties. The in-situ fabrication approach can potentially be a one-pot solution to HER electrode synthesis. In this study, polyolefins pyrolysis gas and a Co:Ni:Mg catalyst were used to fabricate binder-free CNTs-based electrodes on different substrates for HER. The study assessed CNT quality on conductive carbon paper, semiconductive silicon, and dielectric glass substrates, evaluating their HER performance in 1 M KOH. A mixture of hollow-core, bamboo-like, and cup-stacked arrangement nanotubes were synthesized on the substrates, with CNTs on glass and carbon paper substrates possessing better graphitization than CNTs grown on silicon. This is in agreement with HER performance, whereby the as-prepared electrodes required overpotentials of 267 mV, 241 mV, and 216 mV for silicon, glass, and carbon paper, respectively, to achieve 10 mA/cm2. Despite being poorly conductive, the glass substrate electrode achieved a lower overpotential than the silicon electrode. Additionally, the as-prepared silicon electrode faced a delamination issue likely attributed to the lower surface energy of the silicon substrate surface, demonstrating the weaker adhesion between the CNTs and silicon surface. The proposed approach thus showed that the in-situ fabricated electrodes performed better than separately synthesized CNTs prepared into electrodes by 27.4% and 14.2% for carbon paper and glass substrates, respectively. The improved performance of the as-prepared, binder-free electrodes can be linked to the lower charge-transfer resistance and reduced contact resistance between the CNTs and substrate.

Fe-FeNn nanoparticles anchored bamboo-like morphology of N-doped graphitic carbon nitride nanotubes enabled electrochemical DNA-based biosensing of head and neck-squamous cell carcinoma miRNA-203

We describe a biosensing platform for the early screening of metastatic lymph nodes in patients with head and neck squamous-cell-carcinoma. The tunable iron nanoparticles (Fe-FeNn) inserted bamboo-like nanostructured N-doped carbon nanotubes (CNTs) obtained from a graphitic carbon nitride (GCN) are a source material for the highly sensitive detection of miRNA-203 in human serum and urine samples. The CNTs/GCN with tunable Fe precursors annealed at 900 °C enables the formation of Fe-FeNn nanoparticles (n = 0.5, 1.0, and 2.0 mmol of Fe) intercalated bamboo-like morphology of CNTs/GCN, which is denoted as Fe-FeNn/CNTs/GCN nanocomposite. Particularly, the bamboo-like nanotubes were derived from layered-structure of graphitic carbons with several voids and pores. The synthesized bamboo-like Fe-FeNn/CNTs/GCN was used to construct a biosensing platform through coordinate covalent bonding between Fe-FeNn and phosphate functionality of probe DNA. The developed bamboo-like Fe-FeNn/CNTs/GCN-based biosensing platform exhibited potential detection toward cancerous miRNA from 10 to 5000 fM with the limit of detection of 0.11 fM (S/N = 3). Under optimized conditions, the developed Fe-FeNn/CNTs/GCN biosensing platform was applied to detect miRNA in complexed biological fluids, such as human blood serum and saliva samples with satisfied recovery results (94.22%–97.40%).

Dual-MOFs-Derived Fe and Mn Species Anchored on Bamboo-like Carbon Nanotubes for Efficient Oxygen Reduction as Electrocatalysts

The development of efficient non-precious metal electrocatalysts for oxygen reduction reaction (ORR) to replace Pt-based methods is crucial for the applications of fuel cells and metal–air batteries. In this study, a bimetallic M-N-C catalyst with highly dispersed dual-atom Fe/Mn-Nx sites immobilized on N-doped bamboo-like carbon nanotubes is prepared by the ball-milling and calcination of dual-MOFs as precursors. The rich N-doping and abundant M–Nx species contribute to the excellent intrinsic ORR activity of the catalyst, and the unique bamboo-like nanotubes morphology is beneficial for facilitating electron transfer and mass transport while simultaneously enabling the exposure of active sites. As expected, the optimized Z-Fe1Mn1-NC catalyst exhibits efficient ORR activity with a half-wave potential (E1/2) of 0.80 V in acid and 0.82 V in alkaline, and a higher electrochemical stability with the current density maintained at 91% (in 0.1 M KOH) and 86% (0.1 M HClO4) of its initial current density after 15 h of a chronoamperometric test at a high potential of 0.7 V. When further applied to Zn–air batteries, the catalyst also delivers a high open-circuit voltage, large power density, and outstanding rate performance. This work provides a novel means of designing dual metal M–Nx site-based M-N-C catalysts for ORR sustainable energy applications.

Bamboo-like N-doped carbon tubes encapsulated Co2P–Fe2P derived from zeolitic imidazolate framework as an efficient trifunctional electrocatalyst for water splitting and Zn-air batteries

The development of high-performance and stable trifunctional electrocatalysts is a pressing challenge for the practical application of water splitting and regenerative Zn-air batteries. Herein, bamboo-like N-doped carbon tubes encapsulated Co2P–Fe2P nanoparticles (CoFe-PN/C) was fabricated via a facile template-sacrificial approach by using CoZn-ZIF trapping Fe3+ (CoFeZn/C) as the precursor. The incorporation of Fe3+ was achieved by the one-pot synthesis approach during crystallization of ZIF, which led to the generation of the unique bamboo-like tube structure under the condition of simultaneous phosphating and carbonization. Benefiting from the large surface area, the optimized electronic structure of active sites and the unique bamboo-like nanotube, the resultant CoFe-PN/C can be used as the trifunctional electrocatalyst possessing a small overpotential at 10 mA cm−2 for the HER (178 mV) and OER (300 mV), as well as a high half-wave potential of 0.884 V for ORR (40 mV more positive than that of commercial 20 wt% Pt/C). Moreover, the self-designed CoFe-PN/C||CoFe-PN/C alkaline electrolyzer driving 50 mA cm−2 only need operating potential of 1.84 V and the maximum discharge power density of the CoFe-PN/C-assembled ZABs could achieve 152.0 mW cm−2, superior to those of Pt/RuO2 couple. This work will facilitate the development and application of trifunctional electrocatalysts based on bi-transition metallic phosphides for energy conversion and storage technology.

ϵ-Fe3N@N-doped carbon core-shell nanoparticles encapsulated in bamboo-like carbon nanotubes for oxygen reduction reaction electrocatalyst

Exploring economically efficient electrocatalysts with robust oxygen reduction catalytic activities and developing appropriate structures are necessary to understand fuel cells with high open-circuit voltages and long lifespans. In this work, a high-performance ORR catalyst was prepared with a one-spot method by pyrolysis of a urea, FeCl3, and NaCl mixture. The surface element distribution was studied by XPS etching, showing the active sites ϵ-Fe3N with active Fe–N bonding. Benefiting from the double layer protection, in which the ϵ-Fe3N nanoparticles were covered by an N-doped carbon layer encapsulated in carbon bamboo-like nanotubes, the catalysts showed abnormal stability with 5000 cycles, a negative shift of only 15 mV by the CV test and a 3% attenuation after 60,000 s of operation. The onset potential is found to be 0.96 V, which is a positive shift of 12 mV compared to that of the state-of-the-art Pt/C catalyst. The ORR kinetic analysis indicates that the catalyst shows a Tafel slope of 82 mV decade−1 at high potential and 130 mV decade−1 at low potential close to that of the reference catalyst, suggesting a similar reaction mechanism. Therefore, successfully synthesized nonnoble electrocatalysts offer a novel strategy and promising candidates to promote the further development of clean energy devices.

Morphology control of CdSe nanocrystallines

CdSe nanocrystallines with different micromorphology were synthesized by inverse microemulsion method. X-ray diffraction and transmission electron microscopy were used to characterize the micromorphology, phase and ingredient compositions of nanocrystallines. The results indicate that nanosphere, necklace-shaped and bamboo-likeCdSe nanocrystals were successfully prepared. The bamboo- like nanotubes have the best crystallization performance. The red shift of the fluorescence peak can be observed clearly, and bamboo-shaped nanotubes have stronger fluorescence emission. Detailed study on the formation of bamboo-like nanotubes was performed. The mechanism is as follows: the difference of the bound water content at the interface and the free water content in the water core leads to the density difference between outer layer and the center. The diffusion of Se2- and Cd2+induces hollow structure of CdSe nanospheres. Due to the small size effect, hollow nanospheres grow into necklace-shaped and bamboo-structure finally

Preparation of bamboo-like carbon nitride nanotubes, spheres, and study of their structural, morphological and optical properties

A large-scale bamboo-like carbon nitride nanotube powder has been prepared on Nichrome60 and quartz substrates at 800 °C by Chemical Vapor Deposition (CVD)-Pyrolysis technique using Triazine as a precursor. X-ray diffraction analysis indicates that the as-prepared powder contains a crystalline alpha carbon nitride (α-C3N4) structure with lattice parameters a=6.71 Å, c=4.65 Å and c/a=0.69. The selected area electron diffraction (SAED) pattern, with three diffused circles, confirms the existence of the crystalline α-C3N4 phase . High-resolution TEM images depict carbon nanotubes possessing both even and uneven compartments in the nanotube. X-ray photoelectron spectroscopy confirms the presence of both sp3 and sp2 bonding between carbon and nitrogen atoms for the formation of the α-C3N4 structure. The calculated overall nitrogen content is 17 at. % which is far less than the expected value, but induces compartment formation. The optical bandgap (Eg) of the carbon nitride was evaluated and was found to be 5.5 eV. A mechanism is proposed for the formation of uneven compartment structures in the CNTs. Both even and uneven compartments containing carbon nitride nanotubes (CNNTs) could be ideal for developing hydrogen storage materials.

Synthesis of carbon nanotubes using pre-sintered oil fly ash via a reproducible process with large-scale potential

Oil fly ash (OFA) is a byproduct generated by the burning of heavy crude oil in factories and power plants. Millions of tons of OFA is produced annually worldwide and is mostly treated as solid waste. Extensive efforts have been made to utilize OFA and reduce its environmental effects. Recently, OFA has been found to be a suitable catalyst and co-precursor for carbon nanotube (CNTs) production. However, the treatment methods used are expensive and time consuming. Here, we describe a new method for OFA treatment and provide optimized growth conditions for CNTs production. Pre-sintering of OFA at elevated temperatures (400-450 °C) in air or vacuum using a chemical vapor deposition (CVD) tube furnace (80-100 min) is a very effective treatment method for CNTs growth under optimum growth conditions. The optimum parameters for CNTs growth were growth temperature, gas pressure, gas flow rate, and growth time. Well-defined, thin nanotubes with diameters of 20-40 nm were produced. Bamboo-like nanotubes with zigzag curved walls were also observed in the produced CNTs. The weight percentage of the produced CNTs was approximately twice that of the treated OFA. Consequently, the pre-sintering method exhibited suitability for the mass production of CNTs. Thus, large quantities of the nanomaterial can be supplied for use in various applications, e.g., polymer composites, the rubber industry, construction materials, and lubricant additives.

In situ construction of FeCo alloy nanoparticles embedded in nitrogen-doped bamboo-like carbon nanotubes as a bifunctional electrocatalyst for Zn-air batteries.

The rational design and exploration of low-cost, highly efficient, and robust bifunctional oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) electrocatalysts are essential for the application of zinc-air batteries. Herein, a novel highly active and stable oxygen electrode catalyst is designed based on in situ construction of FeCo alloy nanoparticles embedded in nitrogen-doped carbon nanotubes (FeCo/N-CNTs-800) with a bamboo-like structure. The unique architecture of bamboo-like nanotubes, the large surface area with abundant mesoporous structure, and the strong coupling interactions between the encapsulated alloy nanoparticle core and the nitrogen-doped graphitic carbon shell synergistically enhance the electrocatalytic activity. As a result, FeCo/N-CNTs-800 exhibits remarkable ORR (with a half-wave potential of 0.891 V in 0.1 M KOH) and OER (with an overpotential of 359 mV to deliver 10 mA cm-2 in 1 M KOH) performance, respectively. More impressively, an assembled zinc-air battery with the bifunctional FeCo/N-CNTs-800 catalyst as the air electrode demonstrates a large power density of 200.4 mW cm-2 and robust cycling performance over 445 h compared to precious-metal catalysts Pt/C∥IrO2. Thus, the electrocatalyst presented in this work holds great potential as an air cathode for practical applications of zinc-air batteries.

Greenery-inspired nanoengineering of bamboo-like hierarchical porous nanotubes with spatially organized bifunctionalities for synergistic photothermal catalytic CO2 fixation

The hollow tubular core–shell photocatalyst (Ni-BNCNTs@HMPs-NH2) exhibits superior activity and stability for the photothermal conversion of CO2 to cyclic carbonates under mild and co-catalyst/solvent-free conditions.

Fabrication of Mno2/Tio2 Bamboo-Like Nanotube Arrays Nanocomposites and its Enhanced Photocatalytic Degradation Performance and Mechanism

Fabrication of Mno2/Tio2 Bamboo-Like Nanotube Arrays Nanocomposites and its Enhanced Photocatalytic Degradation Performance and Mechanism

Fabrication of Mno2/Tio2 Bamboo-Like Nanotube Arrays Nanocomposites and its Enhanced Photocatalytic Degradation Performance and Mechanism

Fabrication of Mno2/Tio2 Bamboo-Like Nanotube Arrays Nanocomposites and its Enhanced Photocatalytic Degradation Performance and Mechanism

Bamboo-like carbonitride nanotubes with multi-type active sites for oxygen reduction reaction in both alkaline and acid mediums

To omni-directionally utilize carbon-based material in nanoscale and improve its catalytic activity for oxygen reduction reaction (ORR), bamboo-like carbonitride nanotubes (bCNTs) with high-density multi-type active sites (CoO@Co–N-bCNT) are facilely synthesized via a multi-step method referring to thermal pyrolysis of Co2+ complexed melamine, acid leaching and second annealing. Multi-type active sites including encapsulated Co nanoparticles, intercalated Co/CoO species, Co-Nx coordinated sites and defect-rich surface are present in the as-prepared CoO@Co–N-bCNT electrocatalyst. The types and densities of these active sites are easily tuned via the ratio of melamine to Co2+ in precursors and subsequent treatment. Due to the high-density multi-type active sites and bamboo-like tubular structure, CoO@Co–N-bCNT electrocatalyst exhibits high catalytic activity for ORR with high stability in both alkaline and acid electrolytes. Quasi-solid-state zinc air battery (ZAB) assembled with the CoO@Co–N-bCNT as the cathode exhibits open circle voltage of 1.39 V and peak power density of 14.9 mW cm−2. Two-cell series of quasi-solid-state ZABs can light LED indicator for 7 h, suggesting its promising practical application. The studies provide facile strategy to design the carbon-based electrocatalysts with high performance and tune their active sites.

Synthesis of polycrystalline boron nitride nanotubes with Lead(II) oxide and Iron(III) nitrate nonahydrate as promoters

Boron nitride nanotubes (BNNTs) possess many fascinating properties that make them promising for various applications in microelectronics, biomedicine and coating. In this work, BNNTs were synthesized by a ball milling-annealing method. Boron powder was milled with promoters, lead(II) oxide (PbO) and iron(III) nitrate nonahydrate (Fe(NO 3 ) 3 ⋅9H 2 O), under the N 2 gas environment to prepare a precursor. Then, bamboo-like and cylindrical BNNTs were synthesized by annealing the precursor at 1150 °C under the NH 3 gas environment. The phase of the BNNTs was identified to be hexagonal BN by X-ray diffractometry, Raman spectroscopy and transmission electron microscopy . The effect of the promoter content in the precursor on the synthesis of the BNNTs was investigated. When the mass ratio of B:PbO:Fe(NO 3 ) 3 ⋅9H 2 O was 1:1:1, bamboo-like and cylindrical BNNTs with a diameter of 60–500 nm, uniform composition and polycrystalline microstructure were obtained. • Polycrystalline BN nanotubes are synthesized by ball milling and annealing. • PbO and Fe(NO 3 ) 3 ⋅9H 2 O are efficient promoters for the synthesis of BN nanotubes. • The diameters of the cylindrical and bamboo-like BN nanotubes are 60–500 nm.

Sulfonated polydivinylbenzene bamboo-like nanotube stabilized Pickering emulsion for effective oxidation of olefins to 1,2-diol

Sulfonated polydivinylbenzene bamboo-like nanotube (SPDVB) with effective olefins oxidation activity is prepared by combining cationic polymerization and sulfonation. By merely adjusting sulfonation time, SPDVB with different sulfonic acid group (–SO3H) contents is achieved. SPDVB is used as both a solid emulsifier and catalyst to fabricate Pickering emulsion interface catalytic system for oxidizing olefins with 30% H2O2 acting as oxidant/water phase and olefins acting as reactants/oil phase. It is shown that Pickering emulsion interface catalytic system stabilized by SPDVB exhibits enhanced olefins oxidation efficiency than the conventional ones. At the optimum catalyst and reaction condition, the conversion of olefins by Pickering emulsion interface catalytic system stabilized by SPDVB for cyclohexene, 1-methylcyclohexene, cyclooctene, 2,3-dimethyl-2-butene oxidation is higher than 90.00% and the corresponding 1,2-diol selectivity exceeds 93.00% except the selectivity to 1-methyl-1,2-cyclohexanediol. The catalytic system also exhibits excellent cycling performance (>95.00% olefins conversion and >89.00% 1,2-diol selectivity for cyclohexene/2,3-dimethyl-2-butene oxidation after four cycles). A possible mechanism for oxidation of olefins to 1,2-diol by SPDVB stabilized Pickering emulsion is proposed: the high catalytic interface area between sulfonic acid group and H2O2 in water phase enhances the sulfonic acid group of SPDVB to convert into peroxysulfonic acid (catalytic activity centre) firstly; then the formed peroxysulfonic acid attacks the double bond of olefins to form epoxide intermediates, which will be hydrolyzed to 1,2-diol.

Controlling the Structure of Carbon Deposit by Nitrogen Doping Catalytic Chemical Vapor Deposition Synthesis.

Nitrogen doped multi-walled carbon nanotubes and other carbon nanoparticles were synthesized by catalytic chemical vapor deposition of tripropylamine and acetylene on CaCO₃-supported cobalt catalyst (5 wt%), prepared by impregnation, and various precursors. Each synthesis was performed by using either the pure nitrogenous organic compound or its mixture with acetone. Transmission electron microscopy studies revealed a significant difference both in the yield and the diversity of the carbon deposits. Every synthesis resulted in bamboo-like nanotubes, and nearly all of them also in onion-like structures. Electron energy loss spectroscopy studies of the samples indicated the presence of nitrogen and calcium (caused by the catalyst support). High-resolution transmission electron microscopy and X-ray diffraction measurements were also performed to characterize the samples.

Effect of processing temperature on growing bamboo-like carbon nanotubes by chemical vapor deposition

The present article demonstrates a simple, eco-friendly route for the fabrication of carbon nanotubes (CNTs) with different morphologies, including the fascinating bamboo-like structures without complex catalyst/support preparation procedures. A thermal chemical vapor deposition (CVD) technique that utilized natural pozzolan supports and a solid carbon source, that is, a mixture of camphor and ferrocene in a weight ratio of 20:1, was carried out at different temperatures where the ferrocene played also the role of catalyst. The pozzolan chemical composition and mineral identification were determined by energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy. The morphology of the fabricated CNTs was studied via scanning and transmission electron microscopies (SEM and TEM). It was revealed that both conventional tubular and bamboo-like nanotubes grow at 750 °C while the bamboo-like morphology prevails at 850 °C. The better nanostructure uniformity at higher deposition temperature was accompanied by an improved nanotube graphitization degree that was verified by Raman spectroscopy. Yet, the reduction of the CNTs production yield was recorded by thermogravimetric analysis (TGA). The experimental data are interpreted and discussed as an interplay between the CNTs processing temperature, morphology and growth mechanism. Thus, the growth of either tubular or bamboo-like nanostructures is suggested to be ruled by the competitive surface and bulk diffusions of carbon onto and into the catalyst surface. The growth depends on the size of catalyst nanoparticles sintered at different temperatures. The favorable role of the pozzolan supporting materials in the formation of bamboo-like tubes is emphasized.

A cost-saving preparation of nickel nanoparticles/nitrogen-carbon nanohybrid as effective advanced electrode materials for highly sensitive tryptophan sensor

Here we report a facile and cost-effective preparation of nickel nanoparticle S/Nitrogen-carbon nanohybrid (Ni NPS/N-C) based on formamide condensation and carbonization, used for highly sensitive and selective electrochemical determination of tryptophan (Trp) in practical samples. The crystallographic phase, surface morphology, elemental distribution, and chemical state of the Ni NPS/N-C nanohybrid were analyzed by XRD, SEM, TEM, EDS, XPS, FTIR, TGA and Raman spectra. The results show that high content of Ni NPs (6.62 wt%) were distributed in the nanohybrid, and a large number of bamboo-like nanotubes were formed during pyrolysis, which dramatically increases the specific surface area, and remarkably promotes the electrical conductivity as well as the catalytic activity of the nanohybrid. The electrochemical behavior of Trp was investigated on the nanohybrid modified carbon paste electrode (Ni NPS/N-C/CPE) and the measurement parameters were optimized. As expected, the modified electrode can remarkably enhance the electrochemical oxidation signal of Trp. Under the optimal experimental conditions, a linear relationship in the range of 0.01–20 μM and 20–80 μM for Trp was established with detection limit of 5.7 nM (S/N = 3). Finally, the proposed sensor was practically applied by evaluation and determination of Trp from various sourcing samples including human serum and pharmaceutical samples.

3D hierarchical porous hybrid nanostructure of carbon nanotubes and N-doped activated carbon

In this work, carbon nanotubes (CNTs)/nitrogen-doped activated carbon (AC) hybrids were designed and fabricated using a facile and one-step synthesis. The synthesis of CNTs is based on the recently discovered phenomenon of thermally-induced polyfurfuryl alcohol (PFA) conversion. Hybrid materials are fabricated through the in-situ free growth of closed carbon nanotubes on low-cost activated carbon substrates which were obtained from green algae or amino acids. Herein, three types of carbon nanotubes were observed to freely grow on an activated carbon background from Chlorella vulgaris or l-lysine, types such as multiwalled carbon and bamboo-like nanotubes, whose structure depends on the background used and conditions of the synthesis. Structure type is identified by analyzing transmission electron microscopy images. HRTEM images reveal the tubes’ outer diameter to be in the range of 20–120 nm. Because the carbon surface for the growth of carbon tubes contains nitrogen, the final hybrid materials also possess pyridinic-N and quaternary-N groups, as indicated by X-ray photoelectron spectra.