Porous CNTs Research Articles

Sulfonic group modified carbon nanotubes: the decorative strategy for enhancing the performance of lithium-sulfur batteries

Sulfonic group-modified thin-walled porous CNTs are successfully designed by reacting with sulfuric acid, and enhance the electrochemical performance of lithium-sulfur batteries by dispersing sulfur and adsorbing polysulfides.

Facile in-suit solid-phase synthesis of carbon-coated Ni2P nanospheres decorated on carbon nanotubes with high performance in both supercapacitors and lithium-ion batteries

Low specific surface area and severe agglomeration are the main defects of the energy storage materials (ESMs) fabricated by the solid-phase synthesis (SPS) method. If these defects could be well addressed, the SPS method would be a promising method for the fabrication of high-performance ESMs with the merits of convenience, eco-friendliness, and cost-effectiveness. In this work, an in-suit solid-phase synthesis method is developed for the synthesis of the Ni2[email protected]/CNT nanocomposite with high performance in both supercapacitor and lithium-ion battery. The carbon-coated Ni2P nanospheres are in-suit synthesized and decorated successfully on the porous high-conductive CNTs framework by the proposed method. An ultra-high specific capacity of 378.5 mAh g−1 at 1 A g−1 and a good rate capacity (189.3 mAh g−1 at 20 A g−1) are presented by the synthesized nanocomposite. Meanwhile, high performance is achieved in both supercapacitor and lithium-ion battery application. Compared to the transition metal phosphide-based nanocomposites reported in literature prepared by the traditional methods, the Ni2[email protected]/CNT nanocomposite prepared by the proposed in-suit SPS method exhibits very competitive performance in both supercapacitor and lithium-ion battery. The proposed in-suit SPS method is proved to be a promising method for the preparation of high-performance ESMs.

A novel ternary nanocomposite based electrochemical sensor coupled with regularized neural network for nanomolar detection of sunset yellow FCF

Synthetic dyes are extensively used worldwide although they instigate adverse environmental and health issues at higher concentrations. A reliable and ultrasensitive electrochemical sensor for nanomolar determination of common food colorant sunset yellow FCF is reported in this paper. The electrochemical sensor was integrated with a regularized neural network to enable intelligent sensing of this azo dye. The sensor was fabricated using a ternary nanocomposite based on silver doped spinel Co3O4 nanorods embedded functionalized multi-walled carbon nanotubes (fCNTs). Co-precipitation method was employed for synthesis of porous Co3O4 nanorods and CNTs were functionalized using acid-treatment approach. Electrochemical investigations based on cyclic voltammetry and differential pulse voltammetry techniques revealed stupendous electrocatalytic performance towards sunset yellow detection. A nanomolar detection limit of 0.8 nM and high sensitivity of 8.79 μA μM−1 cm−2 was exhibited by the developed sensor and real sample analysis experiment was conducted in commercial beverages to validate its practical feasibility.

Synergistic Defect Engineering and Interface Stability of Activated Carbon Nanotubes Enabling Ultralong Lifespan All-Solid-State Lithium-Sulfur Batteries.

Due to the high energy density, high safety, and low cost of sulfur, all-solid-state lithium-sulfur batteries (ASSLSBs) are considered one of the most promising next-generation energy storage devices. Nevertheless, the insufficient interfacial contact between solid electrolytes (SEs) and the active material of sulfur leads to inadequate electronic and ionic conduction, which increases interfacial resistance and capacity decay. In this paper, commercial carbon nanotubes (CNTs) are activated to form porous-CNTs (P-CNTs), which are used as sulfur-bearing matrix, forming S@P-CNTs-based composite cathodes for ASSLSBs. Compared with CNTs, P-CNTs possess a larger specific surface area and more oxygen-containing groups, providing enhanced interfacial contact and stability between S@P-CNTs and Li6PS5Cl SE, which are confirmed by scanning electron microscopy, X-ray photoelectron spectroscopy, and density functional theory calculations. Moreover, P-CNTs can form a 3D conductive network in the composite cathodes, facilitating the migration of electrons and the diffusion of ions, as well as improving the utilization of sulfur. As a result, the S@P-CNTs-based ASSLSBs display excellent electrochemical performances, especially rarely reported ultralong lifespan, which deliver a capacity of 1099.2 mA h g-1 at a current density of 1.34 mA cm-2, and remarkably maintain 70.4% of the initial capacity over 1400 cycles.

Biomimetic design of gradient and hierarchical platform based on carbon nanotubes and porous carbon polyhedrons for strain sensors and beyond

Currently, stretchable strain-sensing platforms are highly desirable for the full-range and accurate detection of human motions. However, it is also a grand challenge to fabricate strain sensors with a large sensing range, high sensitivity, and low detection limit. Inspired by the gradient and hierarchical structures in bones, a high-performance and multifunctional sensing platform with a gradient component distribution was reported by selecting porous carbon polyhedrons (PCP), PCP-welding-carbon nanotubes (PCP-w-CNTs), and CNTs as the functional nanomaterials to construct a novel bone-mimicking gradient conductive network by a facile layer-by-layer assembly, and elastic poly(styrene-block-butadiene-block-styrene) as the periosteum-like coating to being attached to conductive networks. Benefiting from the gradient structure and junction welding by manipulating the vertical component distribution of conductive fillers and in situ deposition, the strain sensors could detect small and large deformations with an ultralow detection limit (∼0.01% strain), a large sensing region (∼660% strain), high sensitivity (∼5797.83), fast response/recovery time (∼180/180 ms), and excellent robustness (∼1000 stretch-release cycles). Moreover, the composites can sense liquids due to their different solubility parameters.

Hybrid nanotubes constructed by confining Ti0.95Nb0.95O4 quantum dots in porous bamboo-like CNTs: superior anode materials for boosting lithium storage.

Current commercial lithium ion battery (LIB) anodes comprising graphite and Li4Ti5O12 inevitably suffer from safety risk and low energy density. Hence, a novel anode material of Ti0.95Nb0.95O4/C hybrid nanotubes was developed via a modified sol-gel method combined with subsequent calcination. The hybrids consist of Ti0.95Nb0.95O4 quantum dots that are homogeneously embedded in the walls of porous bamboo-like CNTs. The high capacity feature of multiple redox couples of Ti-Nb-O based anodes is demonstrated by ex situ XPS in the hybrids. With the advantages of stimulative lithium storage, increased conductivity and robust mechanical properties due to the unique hybrid structure, the hybrids exhibit a high capacity (516.8 mA h g-1 at 0.2 A g-1), superior long-term cycling stability (142.7 mA h g-1 at 5 A g-1 after 3000 cycles) and an ultra-high rate capability (234.6 mA h g-1 at 1 A g-1 and 125 mA h g-1 at 8 A g-1). Meanwhile, the hybrids showed superior electrochemical performance compared with the reported Li4Ti5O12 and Ti-Nb-O based anodes. Furthermore, the GITT measurements revealed the fast Li+ transport for the charge-discharge processes of the hybrids. Such prominent merits of the Ti0.95Nb0.95O4/C hybrid nanotubes make them more likely candidates that can replace graphite and Li4Ti5O12 anodes in LIBs.

SENSOR ELETROQUÍMICO PARA MONITORAMENTO DE SUOR

ABSTRACT Introduction: Attention is given to developing electrochemical sensors for the rapid and real-time measurement of lactate levels. The synthesis of electrochemical sensors is based on an electrode modified with a nanocomposite. Objective: Analyze an electrochemical sensor's feasibility for sports monitoring sweat in lactate. The Au@CNTs were the main focus of this study. Methods: The Au@CNTs composite was synthesized on the GCE surface and tested under pre-established protocols as a sensor. Results: The shape and structure of the modified electrodes were analyzed using SEM. The results showed that the Au@CNTs nanoparticles in the Au@CNTs nanocomposite were evenly distributed throughout the porous CNTs network. The performance of the developed sensor was measured using cyclic voltammetry and amperometry. The electrochemical biosensor responded linearly to lactate over phosphate buffer solution with a low detection limit and sensitivity. Conclusion: The experiment of this sensor evaluated lactate concentrations in real sweat samples that were exceptionally close to the injection amount, enabling it as an effective biosensor for the detection of lactate in sweat samples. Level of Evidence: Therapeutic Studies - Outcome Investigation.

Metal‐Organic Frameworks: Synthesis, Structures, and Applications

Metal‐Organic Frameworks: Synthesis, Structures, and Applications

In-situ growth of CNTs-porous carbon from asphalt with superior double-layer capacitive performance

Carbon materials have been engaged in supercapacitor, but the commercial biomass and coal-based carbon were far from satisfactory due to the hard control of pore structure and inferior electric conductivity. Newly developed carbon materials or composites, such as porous graphene or CNTs based materials were suffering from high cost or hard to balance energy and power densities. Herein, we obtained a CNTs-porous carbon by directly controlling the pyrolysis process of the petroleum asphalt. The composite combined both porosity and the conductive pathways for the migration of ions and electrons. The existence of a little S, N heteroatoms contributed to the infiltration of the aqueous electrolyte. The obtained symmetric supercapacitor demonstrated a superior capacitance of 385.7 F g−1 at the current density of 1 A g−1 with 93.8% capacity retention after 10,000 cycles under 4 A g−1. This material provided an optimistic choice for high-power equipments.

Structure-controlled Ni@N-doped porous carbon/carbon nanotube nanocomposites derived from metal-organic frameworks with excellent microwave absorption performance

Structure-controlled nickel @nitrogen-doped porous carbon/carbon nanotube (Ni@NC/CNT) nanocomposites derived from metal−organic frameworks (MOFs) were successfully synthesized via sintering Zn–Ni precursor under the nitrogen atmosphere. Appropriately regulating the molar ratio of Zn-Ni could effectively control the content and length of CNTs and realize unique structures, as demonstrated by X-ray diffraction, scanning electron microscopy and transmission electron microscopy characterization. According to the vector network analyzer test, Ni@NC/CNT nanocomposites displayed outstanding electromagnetic wave absorption performance, which can be attributed to magnetic-dielectric synergy effect, impedance matching, multifarious transmission paths, interface polarization and dipole polarization between Ni nanoparticles (NPs), N-doped porous carbon shell and CNTs. Surprisingly, when the molar ratio of Zn–Ni was 1:3, the maximum reflection loss (RL) of the optimized nickel @nitrogen-doped porous carbon/carbon nanotube-1/3 (Ni@NC/CNT-1/3) nanocomposite reached up to − 74.06 dB at 15.63 GHz with a matching thickness of only 1.911 mm. Furthermore, the largest effective absorption band width (<−10 dB) was as high as 8.54 GHz with a low filler ratio of 10 wt% at the thickness of 5 mm. Hence, these lightweight and broadband MOFs-derived nanocomposites are highly promising for applications requiring excellent microwave absorption performance.

Synergistic carbon coating of MOF-derived porous carbon and CNTs on silicon for high performance lithium-ion batteries

Silicon has been considered as one of the most potential alternatives to traditional graphite anode materials in lithium-ion batteries (LIBs) due to its high specific capacity. However, the practical application of silicon is hampered by its inherent low conductivity and huge volumetric expansion during cycling. Herein, a hybrid of [email protected] nanotubes (CNTs)@carbon nanocomposites in which Si nanoparticles tangled with CNTs are encapsulated into metal-organic-frameworks (MOFs) carbon shell was synthesized through chemical vapor deposition and MOF self-template methods. By growing CNTs on the surface of Si nanoparticles, it is possible to facilitate their encapsulation in ZIF-67 crystals. In addition, the synergistic effect between CNTs and carbon shells doped with nitrogen can efficaciously buffer the expansion of structure and enhance the conductivity of materials. Besides, the porosity of carbon shell and the connection of CNTs can provide channels for the penetration and diffusion of Li+. On the basis of the above merits, the reversible capacity of the resulted composite remains 568.8 mAh g−1 after 200 cycles at 1 A g−1. Moreover, it exhibits a preferable rate performance, thus indicating that this composite is a promising anode material for LIBs.

Electrochemically driven amorphization of (Li-)Ti-P-O nanoparticles embedded in porous CNTs for superior lithium storage performance

Amorphous materials have many advantages over their crystalline states in transfering Li+ without restriction of defects, tolerating large volume change during the charging/discharging process and achieving a higher potential in lithium-ion batteries (LIBs). Crystalline LiTi2(PO4)3/TiP2O7 nanoparticles embedded in porous CNTs were constructed firstly by sol-gel and calcination, in which sulfonated polymer nanotubes as both carbon source and template. Afterwards, amorphous (Li-)Ti-P-O nanoparticles embedded in porous CNTs were formed by electrochemical activation. Due to amorphous (Li-)Ti-P-O nanoparticles providing the multi-channel transport of Li+ and the porous carbon matrix preventing the gathering and pulverization of (Li-)Ti-P-O nanoparticles during the electrochemical process, (Li-)Ti-P-O/C hybrid nanotubes exhibit stable cyclic performances and good rate capacities (the capacities of Li-Ti-P-O/C and Ti-P-O/C hybrid nanotubes possess 388.9 and 457.2 mAh g−1 at 0.2 A g−1 after 500 cycles, and maintain 155.0 mAh g−1 at 5 A g−1 after 500 cycles and 123.3 mAh g−1 at 5 A g−1 after 3000 cycles, respectively). This paper provides a feasible method for the preparation of other anode materials with superior lithium storage performance.

Porous carbon nanotubes microspheres decorated with strong catalyst cobalt nanoparticles as an effective sulfur host for lithium-sulfur battery

The commercialization of lithium-sulfur (Li–S) battery is largely obstructed by the slow redox kinetics of sulfur cathode and the shuttle effect of polysulfides during its operation, which negatively affect the battery rate capability and cycle life. Herein, a porous CNTs/Co microsphere is synthesized and applied as sulfur host material to boost the electrochemical performance of sulfur cathode. The porous conductive CNTs spherical network can realize a rapid charge and mass transfer via fast conduction of Li+-ions and mitigate the cathode volume expansion in the course of the cycles. Importantly, the Co metal nanoparticles can attain intense chemical adsorption and fast catalytic conversion of polysulfides. Because of the above merits, the high initial discharge specific capacity 1242.5 mAh g−1 was obtained for S-CNTs/Co composite at 0.2C. The capacity decay rate was only 0.066% per cycle at 1C over 300 cycles and the excellent rate performance at up to 3C could also be obtained. Moreover, the S-CNTs/Co composite delivered a high initial areal capacity of 5.7 mAh cm−2 at a high sulfur loading (5.9 mg cm−2), indicating broad perspectives of CNTs/Co as a sulfur host in lithium-sulfur battery.

Porous bamboo‐like CNTs prepared by a simple and low‐cost steam activation for supercapacitors

How to prepare porous carbons with appropriate structure for supercapacitors is a big challenge. In general, activation is the simplest way to obtain porous carbons. Porous bamboo-like CNTs were fabricated by simple activating sulfonated polymer nanotubes with steam at 800°C. Compared with the un-activated one, activated carbon nanotubes (ACNTs) have good tubular structure, larger specific surface area and rich porosity thanks to the protection of steam during the activation. The ACNTs electrode for supercapacitors displays a specific capacity of 276 F g−1 at 1 A g−1. When assembling ACNTs into a symmetrical supercapacitor, the specific capacity of the device can retain 98% after 10 000 cycles, and this result shows the great application prospect of ACNTs for supercapacitors.

Insert Zn2+ in Tetrahedral Sites of Bi-metal Zn-Co Spinel Oxides with High Oxygen Catalytic Performance for Liquid and Flexible Zinc-Air Batteries

Nowadays, it is very challenging to develop a low-cost, highly active and stable bi-functional catalyst for accelerating oxygen reduction reaction (ORR) and oxygen evolution (OER) reaction during the charge and discharge process of zinc-air battery. Herein, we successfully design a novel bi-metal oxide hybrid catalyst (ZnCo2O4-CNT) by inserting Zn ions. Benefiting from the robust synergetic effects between porous ZnCo2O4 and CNTs, the high conductivity and the unique nanostructure, the ZnCo2O4-CNT shows lots of accessible active sites and improved reactants and electrons transfer. As expected, the hybrid shows higher ORR and OER performances with larger limited diffusion current density (5.72 mA cm−2) and lower OER over-potential (0.49 V) than Pt/C and other ZnCo2O4-CNT samples. In addition, rechargeable zinc-air battery assembled with the bi-functional catalyst exhibits a high power density of 249.4 mW cm−2, a strong discharge durability and charge-discharge stability of 240 cycles. Notably, the flexible zinc-air battery also shows good battery performances with high power density and good flexibility. Hence, exploiting efficient bi-functional catalytic materials with excellent ORR and OER performance and assembling flexible devices will improve the development of current zinc-air batteries battery industry.

Robust construction of underwater superoleophobic CNTs/nanoparticles multifunctional hybrid membranes via interception effect for oily wastewater purification

A simple and robust strategy is suggested for fabricating multifunctional hybrid separation membrane loading with catalytic nanoparticles based on the interception effect of porous CNTs network membrane. CNTs functionalized covalently with hydrophilic polyacrylic acid brushes assemble into a superhydrophilic/underwater superoleophobic network structure, which displays thickness dependent porosity. This allows the CNTs membrane capture catalytic nanoparticles by simple filtration process and construct flexibly desired separation membrane. Not only effectively separate oil-in-water emulsion, the prepared CNTs hybrid membranes can also catalytically decompose different organic pollutants in water by conveniently altering catalytic nanoparticles in the membrane. This robust construction provides a convenient means to obtain multifunctional CNTs separation membrane, promoting the practical application of superwettable CNTs membrane in the treatment of complex oily wastewater.

Pseudocapacitive Behaviors of Li2FeTiO4/C Hybrid Porous Nanotubes for Novel Lithium-Ion Battery Anodes with Superior Performances.

Hybrid nanotubes of cation disordered rock salt structured Li2FeTiO4 nanoparticles embedded in porous CNTs were developed. Such unique hybrids with continuous 3D electron transportation paths and isolated small particles have been shown to be an ideal architecture that brought out enhanced electrochemical performances. Meanwhile, they exhibited improved extrinsic capacitive characteristics. In addition, we demonstrate a successful example to use cathode active material as anode for lithium-ion batteries (LIBs). More importantly, our hybrids had much superior electrochemical performances than most of the reported Li4Ti5O12-based nanocomposites. Therefore, it is concluded that Li2FeTiO4 can be a prospective anode material for LIBs.

Confined formation of monoclinic Na4Ti5O12 nanoparticles embedded into porous CNTs: towards enhanced electrochemical performances for sodium ion batteries

The nanohybrids of monoclinic Na4Ti5O12 nanoparticles embedded in porous CNTs show excellent rate performance and cycling stability as an anode for sodium ion batteries.

Rational design of hybrid porous nanotubes with robust structure of ultrafine Li4Ti5O12 nanoparticles embedded in bamboo-like CNTs for superior lithium ion storage

Robust hybrid porous bamboo-like CNTs, with ultrafine Li4Ti5O12 nanoparticles homogeneously embedded, which exhibit superior electrochemical performance.

Stable Wettability Control of Nanoporous Microstructures by iCVD Coating of Carbon Nanotubes.

Scalable manufacturing of structured materials with engineered nanoporosity is critical for applications in energy storage devices (i.e., batteries and supercapacitors) and in the wettability control of surfaces (i.e., superhydrophobic and superomniphobic surfaces). Patterns formed in arrays of vertically aligned carbon nanotubes (VA-CNTs) have been extensively studied for these applications. However, the as-deposited features are often undesirably altered upon liquid infiltration and evaporation because of capillarity-driven aggregation of low density CNT forests. Here, it is shown that an ultrathin, conformal, and low-surface-energy layer of poly perfluorodecyl acrylate, poly(1H,1H,2H,2H-perfluorodecyl acrylate) (pPFDA), makes the VA-CNTs robust against surface-tension-driven aggregation and densification. This single vapor-deposition step allows the fidelity of the as-deposited VA-CNT patterns to be retained during wet processing, such as inking, and subsequent drying. It is demonstrated how to establish omniphobicity or liquid infiltration by controlling the surface morphology. Retaining a crust of entangled CNTs and pPFDA aggregates on top of the patterned VA-CNTs produces micropillars with re-entrant features that prevent the infiltration of low-surface-tension liquids and thus gives rise to stable omniphobicity. Plasma treatments before and after polymer deposition remove the crust of entangled CNTs and pPFDA aggregates and attach hydroxyl groups to the CNT tips, enabling liquid infiltration yet preventing densification of the highly porous CNTs. The latter observation demonstrates the protective character of the pPFDA coating with the potential application of these surfaces for direct contact printing of microelectronic features.