Hierarchical Nanotubes Research Articles

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.

Effects of Building Block's Size of Hierarchical In2s3 Nanotubes on Oxidation Coupling of Benzylamines Under Visible Light

Effects of Building Block's Size of Hierarchical In2s3 Nanotubes on Oxidation Coupling of Benzylamines Under Visible Light

Popcorn-like Co3O4 nanoparticles confined in a three-dimensional hierarchical N-doped carbon nanotube network as a highly-efficient trifunctional electrocatalyst for zinc–air batteries and water splitting devices

A novel unique 3D hierarchical structural electrocatalyst is synthesized, where popcorn-like Co3O4 nanoparticles coated with N-doped amorphous carbon anchor onto the tips of N-doped carbon nanotubes (NCNTs), and the NCNTs grow on carbon nanofiber.

Template-free synthesis of Bi2O2CO3 hierarchical nanotubes self-assembled from ordered nanoplates for promising photocatalytic applications.

In this study, we have adopted a one-step hydrothermal route to synthesize an interesting type of Bi2O2CO3 hierarchical nanotubes self-assembled from ordered nanosheets. The effects of reaction time on the morphological and structural evolution, light absorption properties, photoelectrochemical performance, and photocatalytic performance of the prepared hierarchical nanotubes were investigated. Among the products synthesized at different reaction times, the 3-hour-derived Bi2O2CO3 hierarchical nanotubes were identified to possess the highest photocatalytic performance. To promote the photocatalytic application of the as-synthesized Bi2O2CO3 hierarchical nanotubes, their performance was systematically evaluated via the photodegradation of various organic pollutants (e.g., methyl orange (MO), rhodamine B (RhB), methylene blue (MB), ciprofloxacin (CIP), sulfamethoxazole (SMX) and tetracycline hydrochloride (TC)) and the photoreduction of Cr(VI) under simulated-sunlight irradiation. Furthermore, their photocatalytic performance was also evaluated by purifying simulated industrial wastewater (i.e., a MO/RhB/MB mixed solution) at different pH values and containing different inorganic anions. Based on the experimental data and density functional theory (DFT) calculations, the involved photocatalytic mechanism was discussed.

A new approach for simultaneously improved osseointegration and antibacterial activity by electrochemical deposition of graphene nanolayers over titania nanotubes

Simultaneous enhancement of osseointegration and bacterial infection prohibition through surface modifications is a challenging but promising approach to achieve durable implantation. To that end, we present a multifunctional surface coating composed of graphene nanolayers and hierarchical well-aligned TiO2 nanotubes with a nanoporous top layer (cRTNT). FESEM studies reveal tunable increasing island morphologies of graphene nanolayers (G) on cRTNT by a cyclic voltammetry process. XPS analysis shows that the enhanced interface chemistry is due to TiO2-carbon bonding. The roughness of the sample containing a medium amount of graphene, cRTNT-75%GO, was calculated ∼289 nm, which was 543% higher than the Ti6Al4V surface. ALP activity increases by more than 25% for cRTNT/GO samples compared to pure cRTNT. Fluorescent microscopy indicates an approximately 92% decrease in bacterial colony formation and up to 85% improvement in the number of bacteria per field on cRTNT with increasing graphene amount compared to the Ti-6Al-4V surface. Although the increasing amount of graphene up to 95% shows better antibacterial performance, it does not provide a proper surface for adhesion and growth of the bone cells. According to all bio-assays, the nanocomposite coating with a medium amount of graphene (cRTNT-75%G) is proposed as the best sample in terms of biological properties, including improving cell behavior and preventing infection.

Synthesis of hierarchical nickel sulfide nanotubes for highly efficient electrocatalytic urea oxidation

It is a challenge to prepare high-efficiency and inexpensive electrocatalysts toward urea oxidation reaction (UOR). Herein, we report the fabrication of NiS nanotubes with hierarchical sheet-like surface morphology via a novel template-directed hydrothermal reaction as efficient UOR electrocatalyst. The unique hollow structure of NiS nanotubes provides the exposure of more active sites and excellent electron/mass transport properties, ensuring a superior UOR performance. The NiS nanotubes catalyst shows a very low potential at around 1.39 V vs. RHE at 100 mA cm−2 in 1 M KOH/0.33 M urea solution. And the UOR current density of the catalyst at 1.4 V vs. RHE reaches 135 mA cm−2, representing a superior UOR performance. The NiS nanotubes catalyst also possesses an excellent operational stability. Furthermore, a two-electrode urea-assisted overall water splitting (OWS) device assembled with NiS nanotubes as anode and Pt/C as cathode delivers a working voltage of 1.445 V to attain 10 mA cm−2, which is 188 mV less than that for the urea-free OWS electrolyzer, demonstrating its possibility to be applicable for energy efficient hydrogen production. This study provides a rationale to develop high-efficiency non-precious metal-based UOR catalysts for the efficient assistance of hydrogen fuel generation.

MoS2/SnS@C hollow hierarchical nanotubes as superior performance anode for sodium-ion batteries

As a two-dimensional layered material, SnS is considered a promising candidate anode material for sodium storage due to its high theoretical capacity (1022 mA h g−1) and large interlayer spacing (4.33 Å). However, its application is hindered by its large volume expansion and low electronic conductivity. Herein, a unique MoS2/SnS@C hollow hierarchical nanotube with self-supporting structure was synthesized through a facile solvothermal reaction. The results indicate that the hollow nanotube structure can support the material structure and provide a large sodium-ion migration channel. In addition, the heterojunction that formed between SnS and MoS2 can effectively reduce the kinetic barrier of sodium-ion diffusion. Furthermore, the hollow hierarchical nanotube can effectively alleviate the radial and hoop stresses of the SnS sodiation process, inhibit the volume expansion of the material, and increase the capacitance contribution ratio of the material at a high rate. The MoS2/SnS@C composites used as anode materials in sodium-ion batteries (SIBs) delivered excellent rate and cycle performance. The discharge capacity was about 325 mA h g−1 at a high current density of 15 A g−1, and it remained at about 292 mA h g−1 after 2000 cycles at 5 A g−1 current density.

Implication of Wood-Derived Hierarchical Carbon Nanotubes for Micronutrient Delivery and Crop Biofortification.

A similarity of metal alloy encapsulation with the micronutrient loading in carbon nanoarchitecture can be fueled by exploring carbon nanocarriers to load micronutrient and controlled delivery for crop biofortification. A wood-derived nanoarchitecture model contains a few-graphene-layer that holds infiltrated alloy nanoparticles. Such wood-driven carbonized framework materials with legions of open porous architectures and minimized-tortuosity units further decorated carbon nanotubes (CNTs), which originate from heat treatment to carbonized wood samples. These wood-derived samples can alleviate micronutrient nanoparticle permeation and delivery to the soil. A rapid heat shock treatment can help in distributing N–C–NiFe metal alloy encapsulation in carbon frameworks uniformly in that case; higher heating and rapid extinction of heat shock have led to formation of good dispersion of nanoparticles. The wood-carbon framework decorated with metal alloys displays promising electrocatalytic features and cyclic stability for hydrogen evolution. Envisaged from this strategy, we obtain enough evidence to form an opinion that a singular heat shock process can even lead to a strategy of faster growth of a wood-carbon network with well-dispersed micronutrient metal salts in porous matrices for high-efficiency delivery to the soil. Having envisaged the formation of ultrafine nanoparticles with a good dispersion profile in the case of transition metals and alloy encapsulation in the carbon network due to the rapid heating and quenching rates, we anticipate that the loading of micronutrients in the wood-derived nanoarchitecture of carbonized wood derived carbon nanotube (CW-CNT), which can offer an application in seed germination and enhance growth rates of crops. The experience of controlled experiments on germination of tomato seeds on a medium containing CW-CNT that can diffuse the seed coat with the promotion of water uptake inside seeds for enhanced germination and growth of tomato seedlings can be further extended to cereal crops.

Boosting lithium-ion storage performance by ultrafine bimetal carbides nanoparticles coupled with Hollow-like carbon composites

Metallic carbides demonstrated tremendous application potential in energy conversion field deriving from their distinctive electrochemical activity and chemical stability. Herein, a molybdenum-based hybrid self-template strategy was adopted to confine ultrafine molybdenum carbides and tungsten carbides nanoparticles in N, P-codoped carbon nanotubes (MoC/WC@N, P-CNTs) for enhanced lithium-ion storage. Specifically, hierarchical MoW-polydopamine nanotubes were prepared via a self-template strategy, which employed Mo3O10(C6H8N)2·2H2O nanowires as the template. Ultrafine MoC and WC nanoparticles embedded in ultrathin carbon nanosheets could be obtained rationally after carbonization treatment, which could not only prevent carbides nanoparticles from agglomeration and oxidation, but also endow the rapid electron transfer rate. Thus, MoC/WC@N, P-CNTs displayed outstanding lithium storage abilities with great rate property and long-term cycling durability. The stable specific capacity of 475.0 mAh g−1 could be preserved at high current intensity of 5.0 A g−1 after 1000 cycles, which was one of the best performances for metal carbides anodes. Furthermore, the successful fabrication of lithium-ion hybrid capacitors (LIHCs) delivered the maximum energy density of 117 Wh kg−1 and power density of 6571 W kg−1. Moreover, the superior capacity retention of 89.7 % after 2000 cycles also indicated the excellent cycling stability. The present work highlights a self-template strategy for designing nanostructures toward efficient energy storage and conversion fields.

Hierarchical SnO2 hollow nanotubes as anodes for high performance lithium-ion battery

Hierarchical SnO2 hollow nanotubes as anodes for high performance lithium-ion battery

Template-free, facile synthesis of nickel promoted multi-walled MoS2 & nano-bricks containing hierarchical MoS2 nanotubes from the bulk NiMo oxide

A low-temperature and template-free synthesis method was developed to prepare MoS2 nanotubes by sulfidation of bulk NiMo oxide. The ex-situ gas-phase low-pressure sulfidation of NiMo oxide resulted in multi-walled MoS2 nanotubes and NixSy spheres. Meanwhile, the in-situ liquid phase high-pressure sulfidation led to nanotubes formation by self-assembly of MoS2 nano-bricks vertically oriented towards the outer surface as observed by HRTEM analysis. The sulfided catalysts were evaluated for the hydrodesulfurization (HDS) of dibenzothiophene (DBT) in a batch reactor. Catalyst sulfided under ex-situ conditions exhibited good performance (76 % DBT conversion with an initial reaction rate 24 × 10−8 molDBT.(gCat.s)-1). The in-situ sulfided catalyst showed an outstanding activity (99 % DBT conversion with an initial reaction rate 105 × 10−8 molDBT.(gCat.s)-1). Which means that the in-situ sulfidation method dramatically increased the initial reaction rate by four times. A mathematical expression (RKC equation) was derived to correlate the size of the regular hexagonal MoS2 nanoparticles with its activity, for which the experimental results were validated.

Hierarchical mesoporous SnO2 nanotube templated by staphylococcus aureus through electrospinning for highly sensitive detection of triethylamine

In this work, the Staphylococcus aureus (S. aureus) was firstly used as a template coupled with PVP in electrospinning experiments, Sn2+ bonded with S. aureus and PVP to form nanofiber through electrospinning. Finally, we got the hierarchical mesoporous SnO2 nanotube after calcination of the nanofiber. The hierarchical mesoporous SnO2 nanotube as a gas sensor toward triethylamine (TEA) shows high sensitivity, better cycling stability and selectivity. The response and recovery time of the hierarchical mesoporous SnO2 nanotube to 10 ppm TEA are about 19 s and 10 s.

Design of core–shell structure NC@MoS2 hierarchical nanotubes as high-performance electromagnetic wave absorber

Using MnO2 nanowires as a template and coating with polydopamine, the MoS2 nanosheets are uniformly grown on the surface and the core–shell structure MnO2@NC@MoS2 nanowires are obtained after annealing. By etching and removing the MnO2 nanowires template with acid solution, NC@MoS2 wave absorber with tubular hollow structure is obtained. The design of the core–shell structure, the growth of MoS2 nanosheets, the existence of heterogeneous interfaces and the construction of tubular hollow structures effectively enhance the microwave absorption performance of NC@MoS2. The minimum reflection loss (RLmin) is reduced and the Effective absorption bandwidth (EAB) is broadened. Finally, the NC@MoS2 nanotube absorber has a RLmin of −52.56 dB, and the EAB is 6.0 GHz. As an efficient lightweight microwave absorber, NC@MoS2 has potential value in the synthesis and application of new composite microwave absorbing materials.

Li–S Batteries: “Sauna” Activation toward Intrinsic Lattice Deficiency in Carbon Nanotube Microspheres for High‐Energy and Long‐Lasting Lithium–Sulfur Batteries (Adv. Energy Mater. 26/2021)

In article number 2100497, Xin Wang, Zhongwei Chen and co-workers develop a hierarchical porous carbon nanotube microsphere with abundant intrinsic topological defects in the carbon lattice, which promotes sulfur reaction kinetics. The intrinsic carbon defect engineering holds great promise in the development of high-performance Li–S batteries as well as other related energy storage areas.

Hierarchical Architectures Based on Ru Nanoparticles/Oxygen-Rich-Carbon Nanotubes for Efficient Hydrogen Evolution.

Highly active and durable electrocatalysts are essential for producing hydrogen fuel through the hydrogen evolution reaction (HER). Here, a uniform deposition of Ru nanoparticles strongly interacting with oxygen-rich carbon nanotube architectures (Ru-OCNT) through ozonation and hydrothermal approaches has been designed. The hierarchical structure of Ru-OCNT is made by self-assembly of oxygen functionalities of OCNT. Ru nanoparticles interact strongly with OCNT at the Ru/OCNT interface to give excellent catalytic activity and stability of the Ru-OCNT, as further confirmed by density functional theory. Owing to the hierarchical structure and adjusted surface chemistry, Ru-OCNT has an overpotential of 34 mV at 10 mA cm-2 with a Tafel slope of 27.8 mV dec-1 in 1 M KOH, and an overpotential of 55 mV with Tafel slope of 33 mV dec-1 in 0.5 M H2 SO4 . The smaller Tafel slope of Ru-OCNT than Ru-CNT and commercial Pt/C in both alkaline and acidic electrolytes indicates high catalytic activity and fast charge transfer kinetics. The as-proposed chemistry provides the rational design of hierarchically structured CNT/nanoparticle electrocatalysts for HER to produce hydrogen fuel.

Hierarchical Porous Carbon Nanotube Skeleton Supported Polydimethylsiloxane Composite with Electrical Continuity for High‐Performance Electromagnetic Shielding

AbstractElectromagnetic (EM) shielding materials have attracted significant attention, owing to their widespread potential in preventing EM irradiation in electrical devices and human bodies. In this study, a hierarchical porous carbon nanotube (CNT) skeleton with electrical continuity is presented, which is rapidly fabricated via the facile microwave pyrolysis of CNT‐coated organic templates, for constructing high‐performance EM shielding materials. Furthermore, the CNT skeleton, which comprises countless intertwined CNTs, can be easily designed into various configurations, such as CNT foams and CNT sheets, with varying conductivities and pore densities. In the as‐constructed CNT‐skeleton‐supported polydimethylsiloxane (PDMS)/CNT‐foam composites, the continuity of intertwined CNTs leads to a high conductivity of 271.2 S m−1 at a CNT loading of 2 wt%. Owing to the multiple reflections and reabsorption of the EM waves in the hierarchical porous CNT skeleton with macroporous, microporous, and hollow structures, the PDMS/CNT‐foam composites exhibit a high EM shielding effectiveness (SE) of 43 dB, mainly via absorption. Additionally, the electrical continuity of the CNT skeleton allows the dissipation of heat in the PDMS/CNT‐skeleton.

Hierarchical kirigami-inspired graphene and carbon nanotube metamaterials: Tunability of thermo-mechanic properties

Tuning and programming the multiphysical properties of advanced materials are of critical importance for developing the next generation of adaptable multifunctional metamaterials. This study demonstrates the tunability of thermo-mechanical properties of graphene sheets and carbon nanotubes by inspiring from hierarchical kirigami mechanical metamaterials. The theoretical investigation, multiscale simulation, and experimentation show that the thermo-mechanical properties of nano-architected kirigami metamaterials can be tuned by altering geometrical parameters and introducing the hierarchical cutting patterns. Additionally, the thermal conductivity of kirigami-inspired graphene and carbon nanotube metamaterials can be regulated by an external mechanical tension. We develop closed-form formulations for predicting the mechanical behavior of kirigami graphene sheets and carbon nanotubes. Molecular dynamics and finite element simulations are conducted to evaluate theoretical predictions. By analyzing and comparing the results from atomistic and continuum-based simulations, the effect of length scale on the thermo-mechanical properties is explored. We realize that the stress–strain response, thermal conductivity, and buckling-induced 3D patterns of nano-architected graphenes can be programmed by utilizing kirigami building blocks, nano-architectural hierarchy, and heterogeneous material design.

Tailoring hierarchical carbon nanotube cellular structure for electromagnetic interference shielding in extreme conditions

Stable and resilient materials are in great demand for electromagnetic interference (EMI) shielding applications under extreme conditions. Here we present a facile method that could tailor and strengthen the pore structure of carbon nanotube (CNT) foams to obtain highly effective and reliable EMI absorbers that maintain their superior EMI effectiveness under heavy mechanical deformation and extremely high temperature. The hierarchical macro-to-micro pore structure and properties of CNT foam were tailored in a wide range via a secondary chemical vapor deposition (CVD) process. Benefiting from the multi-level reflection in hierarchical pore structures, the optimized CNT foam presents a high shielding efficiency (SE) of 84 dB and a specific SE (SSE/t) of 5.6 × 104 dB·cm2·g-1 in X-band. The tailoring process also provides outstanding stability and mechanical resilience, leading to 83.8% EMI SE maintained after 1000 compressive cycles. Moreover, the foams can keep 76.5% EMI SE after 30 min of 1000°C thermal-destruction process (in argon atmosphere). All these features demonstrate the potential of using the optimized CNT foam as an EMI shielding material under extreme conditions. These findings have essential inspiration for pore engineering in CNT-based EMI shielding materials, giving further guidance for the design of EMI shielding materials used in harsh conditions.

Engineering All-Purpose Amorphous Carbon Nanotubes with High N/O-Co-Doping Content to Bridge the Alkali-Ion Batteries and Li Metal Batteries.

All-purpose electrode materials (APEMs), which can be effectively available on not only alkali-ion batteries but also emerging Li metal batteries, are urgently pursued to open up cost-efficient tactics for practical application of energy storage systems (ESSs), but still remain challenging. Herein, the hierarchical porous carbon nanotubes network (NOPCT) with well-tailored nanoarchitecture and high N/O-co-doping content (20.6 at%) is developed to present large-span application on ESSs. As for Li/Na-ion batteries, the NOPCT delivered excellent cycle stability and robust rate performance in a conventional ester-based electrolyte. Moreover, NOPCT also serving as a metal Li host can effectively guide smooth and uniform Li nucleation/growth to enhance the cycle stability of hybrid Li metal anodes. In addition, the NOPCT played an important role in the sustainability of sulfur electrodes, promising the feasibility of shared NOPCT for practical Li-S batteries. First-principle calculations demonstrate that graphitic-N and CO function groups favor for improving electron conductivity while the pyridinic-N and CO function group make sense for improved Li/Na adsorption and affinity through Lewis acid-base interaction, enlightening the interplay between various doped categories on improved electrochemical performance of NOPCT. This work provides profound theoretical and experimental insight into the design and development of APEMs for advanced ESSs.

Dual-Functional Template-Induced In Situ Polymerization Process Enables the Hierarchical Carbonaceous Nanotubes with Simultaneous Sn Cluster Incorporation and Nitrogen-Doping for Superior Potassium-Ion Storage.

Potassium ion-based energy storage devices have received extensive attention for grid-level applications due to their abundant natural resources and low cost. However, the large ionic radius of K+ leads to inferior capacities and cyclic stability, which hinders their practical application. Herein, hierarchical carbonaceous nanotubes with simultaneous ultrasmall Sn cluster incorporation and nitrogen doping (denoted as u-Sn@NCNTs) are fabricated using MnO2 nanowires as a dual-functional template (in situ polymerization and shape-directing agents) and subsequent carbonization treatment. The u-Sn@NCNTs exhibit a superior K+ storage capability with a high reversible capacity (220.1 mA h g-1 at 0.1 A g-1) and long cycling stability (149.9 mA h g-1 at 1 A g-1 after 4000 cycles). Besides, the u-Sn@NCNTs exhibit superior cycling stability up to 10000 cycles at 5 A g-1 for Na+ storage. The potassium storage mechanism and kinetics are investigated based on ex situ X-ray photoelectron spectroscopy, in situ Raman spectrum, and galvanostatic intermittent titration technique. More importantly, u-Sn@NCNTs can be used as the anode for potassium ion hybrid capacitors, achieving a superior energy density of 181.4 W h kg-1 at a power density of 185 W kg-1 with excellent cycling capability. This work could push forward the development and application of carbonaceous-based anode materials for next-generation high-performance rechargeable batteries.