Carbon Nanotube Framework Research Articles

Integrated Carbon Nanotube and Ketoenamine-Linked Covalent Organic Framework with Positive Charge Structure as High-Performance Capacitive Materials.

A series of composite materials, ETB@CNT (ETB@CNT10, ETB@CNT20, ETB@CNT30, ETB@CNT40, ETB@CNT50) with different carbon nanotubes (CNTs) contents are successfully prepared by using one-pot method. Compared with the pure ET-B-COF, which is a ketoenamine-linked covalent organic framework (COF) with a positive charge structure, CNTs can effectively improve the electrochemical performance of ET-B-COF, and the specific capacitance increased with the increase of the mass of carbon nanotubes added during the preparation process. Among them, ETB@CNT40 exhibits the best electrochemical performance (37.6 F g-1) at a current density of 1 A g-1. This study indicates that the simultaneous introduction of CNTs into COFs can significantly improve the electrochemical performance of ketoenamine-linked COFs materials.

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.

Mechanically Robust Current Collector with Gradient Lithiophilicity Induced by Spontaneous Lithium Ion Diffusion for Stable Lean-Lithium Metal Batteries.

Lean-lithium metal batteries represent an advanced version of the anode-free lithium metal batteries, which can ensure high energy density and cycling stability while addressing the safety concerns and the loss of energy density caused by excessive lithium metal. Herein, a mechanically robust carbon nanotube framework current collector with gradient lithiophilicity is constructed for a lean-lithium metal battery. Using the physical vapor deposition method, precise prelithiation of a carbon nanotube framework is achieved, eliminating its irreversible capacity, retaining the porous structure in the framework, and inducing the gradient lithiophilicity formation due to spontaneous lithium ion diffusion. The lithiophilic gradient and three-dimensional porous structure are characterized by time-of-flight secondary ion mass spectrometry (TOF-SIMS), scanning transmission electron microscopy (STEM), and corresponding electron energy loss spectroscopy (EELS), which enables the preferential deposition of lithium ions at the bottom of the carbon nanotube framework, thereby avoiding lithium losses associated with dead lithium. As a result, in the LiFePO4 full cell with an ultralow N/P ratio of 0.15, the initial Coulombic efficiency increases from 77.75 to 95.07%. Collaborating synergistically with the ultrathin (1.5 μm) lithium metal, serving as a gradual lithium supplement, the full cell with an N/P ratio of 1.43 demonstrates an 86% capacity retention after 500 cycles at 1C, far surpassing the copper-based counterparts (0.9%).

Sulfur-Functionalized Carbon Nanotubes with Inlaid Nanographene for 3D-Printing Micro-Supercapacitors and a Flexible Self-Powered Sensing System.

Digital fabrication of miniaturized micro-supercapacitors (MSCs) holds immense promise for advancing customized, integrated microelectronic systems. As potential electrode materials, carbonaceous nanomaterials, such as carbon nanotubes (CNTs), stand out due to their excellent conductivity and mechanical robustness yet suffer from low ionic storage sites, which restrict further applications. Herein, we introduce a sulfur-assisted in situ activating strategy for obtaining sulfur-functionalized carbon nanotube frameworks integrated with inlaid graphene nanosheets (S-CNT/GNS). Specifically, sulfur functionality enriches the surface charge density with improved interfacial hydrophilicity, while the inlaid nanographene sheets provide abundant ionic adsorption sites. By direct 3D printing of the S-CNT/GNS ink, planar MSCs were fabricated with desirable functionality and outstanding electrochemical performance. Notably, the developed MSCs exhibit a high areal capacitance of 0.47 F cm-2, an exceptional energy density of 64.6 μWh cm-2, and a high-power density of 34.2 mW cm-2. Furthermore, an all-flexible self-powered sensing system with photovoltaic cells and a stretchable sensor was built upon the customized S-CNT/GNS MSCs, demonstrating a highly effective capability for real-time monitoring of human physiological signals and body movements. This work not only presents a promising approach for the development of high-performance MSCs but also lays the groundwork for the creation of advanced wearable/flexible microelectronics systems.

Hierarchical mesh-type oxygen electrode using carbon nanotube framework for anion-exchange membrane-based unitized regenerative fuel cells

Developing three-dimensional porous oxygen electrodes (OE) is crucial for enhancing round-trip efficiency (RTE) of anion-exchange membrane-based unitized regenerative fuel cells (AEM_URFCs). Herein, a novel OE design of AEM_URFCs is presented based on a hierarchical mesh electrode (HME) with a porous carbon nanotube (CNT) framework. The HME, featuring square-shaped macropores achieved by dispersing catalyst nanoparticles on the CNT framework enhances surface area, mass transport, and electron transport. Half-cell test demonstrated superior oxygen reduction reaction and oxygen evolution reaction activity compared to conventional electrodes. Moreover, the HME maintained stable ORR and OER activity during the stability test. In single-cell tests, the AEM_URFCs with the HME exhibited higher RTE (55% at 20 mA cm−2), surpassing the conventional electrode (52%). Furthermore, RTE was maintained at a remarkable 41% under ultrahigh current density (250 mA cm−2), which is unprecedented in the literature. The AEM_URFCs featuring the HME displayed superior cyclability over 5 cycles and durable performances under both fuel cell and water electrolysis modes.

Nanostructured S@VACNTs Cathode with Lithium Sulfate Barrier Layer for Exceptionally Stable Cycling in Lithium-Sulfur Batteries

Lithium-sulfur technology garners significant interest due to sulfur’s higher specific capacity, cost-effectiveness, and environmentally friendly aspects. However, sulfur’s insulating nature and poor cycle life hinder practical application. To address this, a simple modification to the traditional sulfur electrode configuration is implemented, aiming to achieve high capacity, long cycle life, and rapid charge rates. Binder-free sulfur cathode materials are developed using vertically aligned carbon nanotubes (CNTs) decorated with sulfur and a lithium sulfate barrier layer. The aligned CNT framework provides high conductivity for electron transportation and short lithium-ion pathways. Simultaneously, the sulfate barrier layer significantly suppresses the shuttle of polysulfides. The S@VACNTs with Li2SO4 coating exhibit an extremely stable reversible areal capacity of 0.9 mAh cm−2 after 1600 cycles at 1 C with a capacity retention of 80% after 1200 cycles, over three times higher than lithium iron phosphate cathodes cycled at the same rate. Considering safety concerns related to the formation of lithium dendrite, a full cell Si-Li-S is assembled, displaying good electrochemical performances for up to 100 cycles. The combination of advanced electrode architecture using 1D conductive scaffold with high-specific-capacity active material and the implementation of a novel strategy to suppress polysulfides drastically improves the stability and the performance of Li-S batteries.

Carbon Nanotube Network Induces Porous Deposited MnO2 for High-Areal Capacity Zn/Mn Batteries.

Mn2+/MnO2 aqueous battery is a promising candidate for large-scale energy storage owing to its feature of low-cost and abundant crustal reserves. However, the inherent MnO2 shedding issue results in a limited areal capacity and poor cycling life, which prohibits its further commercialization. In this manuscript, it is revealed that the cause of shedding is the cracking of MnO2 layer due to stress. To circumvent this challenge, carbon nanotubes framework is introduced on pristine carbon felt, which provides more deposition sites and induces the formation of a porous deposition layer. Compared to the dense deposition layer on pristine carbon felt, the porous structure can effectively avoid cracking and subsequent shedding issue. Moreover, the porous deposited layer is conducive to proton diffusion and rich in defects, which facilitates the subsequent dissolution reaction. As results, the assembled Zn/Mn battery demonstrates more than 200 cycles with the areal capacity of 15mAhcm-2 at 40mAcm-2. Even with a high areal capacity of 40mAhcm-2, it can still run for more than 60 cycles. This breakthrough paves a way toward practical manganese-based batteries, bringing us closer to achieve cost-effective batteries.

Dendrite‐free Zn deposition initiated by nanoscale inorganic–organic coating‐modified 3D host for stable Zn‐ion battery

AbstractA 3D nanostructured scaffold as the host for zinc enables effective inhibition of anodic dendrite growth. However, the increased electrode/electrolyte interface area provided by using 3D matrices exacerbates the passivation and localized corrosion of the Zn anode, ultimately bringing about the degradation of the electrochemical performance. Herein, a nanoscale coating of inorganic–organic hybrid (α‐In2Se3‐Nafion) onto a flexible carbon nanotubes (CNTs) framework (ISNF@CNTs) is designed as a Zn plating/stripping scaffold to ensure uniform Zn nucleation, thus achieving a dendrite‐free and durable Zn anode. The introduced inorganic–organic interfacial layer is dense and sturdy, which hinders the direct exposure of deposited Zn to electrolytes and mitigates the side reactions. Meanwhile, the zincophilic nature of ISNF can largely reduce the nucleation energy barrier and promote the ion‐diffusion transportation. Consequently, the ISNF@CNTs@Zn electrode exhibits a low‐voltage hysteresis and a superior cycling life (over 1500 h), with dendrite‐free Zn‐plating behaviors in a typical symmetrical cell test. Additionally, the superior feature of ISNF@CNTs@Zn anode is further demonstrated by Zn‐MnO2 cells in both coin and flexible quasi‐solid‐state configurations. This work puts forward an inspired remedy for advanced Zn‐ion batteries.

NiFe layered double hydroxide (LDH) anchored, Fe single atom and nanoparticle embedded on nitrogen-doped carbon-CNT (carbon nanotube) framework as a bifunctional catalyst for rechargeable zinc-air batteries

Zinc-air batteries (ZAB) have significant potential for practical energy storage, but their rechargeability has been limited by the lack of a suitable bifunctional catalyst. Here, we developed NiFe LDH-A-Fe/NC-CNT, a remarkable bifunctional catalyst that is built on a hierarchically porous nitrogen-doped carbon and carbon nanotube (NC-CNT) framework enriched with iron single atoms and nanoparticles, with nickel‑iron layered double hydroxides (NiFe LDH) anchored onto it. The NiFe LDH-A-Fe/NC-CNT exhibited remarkable performance in the ORR, with Eonset of 0.94 V, a half-wave potential of 0.84 V, and a limited current of 6.89 mA cm−2. A remarkable Eonset of 1.47 V and a potential of 1.59 V at 10 mA cm−2 (Ej = 10) in the OER were also observed. Significantly, the difference in potential (ΔE) between the ORR and OER was only 0.74 V. The stability tests, tolerance assessments, and poisoning experiments consistently demonstrated the superior performance of this cutting-edge catalyst in comparison to the commercial Pt/C and RuO2. In ZAB tests, it achieves a discharge capacity of 818 mAhg−1 and an impressive power density of 293 mWcm−2, enduring nearly 1000 cycles (320h). Flexible ZABs with this catalyst maintain a 629 mAhg−1 capacity, a power density of 195 mWcm−2, and a lifespan of 95 h (280 cycles), outperforming benchmark catalysts. In conclusion, a remarkable bifunctional catalyst was synthesized, demonstrating its immense capacity for utilization in zinc-air batteries.

Van der Waals interactions on semiconducting single-walled carbon nanotubes filled with porphyrin molecules: structure optimisation and Raman analysis

This study investigates the Raman analysis of the free base porphyrin (Py) molecule and its encapsulation within a carbon nanotube (CNT) framework using computational simulations.

Structural and dimensional engineering of three-dimensional carbon nanotube/polydimethylsiloxane composite for stretchable sensor

A highly sensitive strain sensor is essential for the wearable electronic in constantly emerging applications such as human motion monitoring, personalized healthcare, human-machine interaction, soft robot and smart skin. However, most of the physical sensors currently reported are facing with challenges of non-adjustable sensing performance, unsatisfactory linearity, complicated preparation processes, and small working ranges, which greatly restricts their practical applicability. In this work, we proposal a facile technology base on the structural and dimensional engineering of carbon nanotube (CNT) conducting networks, to fabricate the flexible and stretchable strain sensor with tunable sensitivity and superior linearity in a wide sensing range. The three-dimensional CNT frameworks with adjustable density were constructed by the chemical vapor deposition method, which were used as the filler network to prepare the flexible CNT/polydimethylsiloxane (CNT/PDMS) composites. The resultant strain sensors base on the CNT/PDMS composites can realize the tunable sensitivities (gauge factor ranges from 0.7 to 233 at 100 % strain) by simply changing and regulating the structural density and macro-size of sensing strips. Meanwhile, the obtained sensors possess excellent linearity (R2 > 90 %) and repeatability on the 10 000 cycles. The technology developed in this work will offer a wide range of practical applications in wearable electronics field.

Hierarchical Structure of CoMn Nanoparticles Encapsulated in N-Doped Carbon Nanotube Frameworks Grown on Nickel Foam for Water Splitting

Hierarchical Structure of CoMn Nanoparticles Encapsulated in N-Doped Carbon Nanotube Frameworks Grown on Nickel Foam for Water Splitting

Acoustic-Activated Se Crystalline Nanodomains at Atomically-Thin Liquid-Metal Piezoelectric Heterointerfaces for Synergistic CO2 Conversion.

Acoustic-activated polarization at two-dimensional (2D) domains provide supplementary mechanisms for adjustment of empty and occupied orbitals at material heterointerfaces, activating a wide range of physicochemical applications. The piezoelectric nanodomains grown at 2D liquid-metal heterointerfaces represent a new class of polarization-dependent hybrid nanostructures with a highly challenging fabrication process. Here, the controlled growth of selenium-rich piezoelectric nanodomains on the nonpolar 2D surface of liquid Ga-based nanoparticles (NPs) enabled highly efficient and sustainable CO2 conversion. The Ga-based NPs were engulfed in carbon nanotube (CNT) frameworks. The initial hindrance effects of CNT frameworks suppressed the undesirable Ga-Se amalgamation to guarantee the suitable functions of piezocatalyst. Simultaneously, the CNT-Se mesoporous network enhances the transport and interaction of ionic species at heterointerfaces, providing unique selectivity features for CO2 conversion. Driven by acoustic energy, the multiple contributions of Ga-Se polarized heterointerfaces facilitated the piezoelectric switching and therefore increased the CO2 conversion efficiency to the value of 95.8%. The inherent compositional and functional tunability of the Ga-Se nanojunction reveal superior control over the catalyst heterointerfaces and thereby show promising potential for nanoscale applications.

Unraveling the carbon dot bridges in oxidized carbon nanotubes for efficient microwave absorption

Carbon nanotube (CNT)-based composites hold immense promise in the realm of electromagnetic (EM) wave absorption. Surface functionalization of CNTs plays a pivotal role in augmenting their surface binding energy, thereby bolstering their affinity for composites. However, the incorporation of functional groups may disrupt the electronic configuration of sp2 plus delocalized π-bonds and impede electronic transport within the CNT framework. Herein, carbon dots (CDs) were introduced onto the surface of oxidized CNTs (O-CNTs) using a one-step hydrothermal method to enhance their bonding capability and microwave absorption performance. Analysis showed that the characteristic functional groups on the surfaces of the CDs formed amide bonds between the CNTs, bridging them with π-conjugated structures and repairing the blocked electron transport pathway triggered by carboxyl groups. The bridging accelerated the electron flow between adjacent CNTs and enhanced the electron jumping and migration in the CDs-CNTs system. Additionally, a comprehensive investigation of the heterogeneous charge distribution within the CDs bridges and their tunable band gap demonstrated their significant influence on polarization relaxation and conduction loss. In short, the study presents a novel functionalization theory for CNTs that exhibit remarkable microwave-absorption performance in X-band.

Boosting redox kinetics using rationally engineered cathodic interlayers comprising porous rGO–CNT framework microspheres with NiSe2-core@N-doped graphitic carbon shell nanocrystals for stable Li–S batteries

Here, we propose the synthesis of a three-dimensional (3D) nanostructure comprising NiSe2-core@N–doped graphitic carbon (NGC) shell nanocrystals securely implanted within a highly conductive and porous reduced graphene oxide–carbon nanotube (rGO–CNT) framework (3D P-NiSe2@NGC/rGO–CNT), using spray pyrolysis technique followed by selenization and utilized as multifunctional cathodic interlayers in lithium–sulfur (Li–S) cells. The uniformly distributed arrays of macropores (ϕ = 100 nm) were formed by thermal decomposition of polystyrene nanobeads (ϕ = 200 nm). The porous structure shortens the charge diffusion length, allowing rapid charge transport and efficient electrolyte percolation besides accommodating unwanted volume perturbations. The NGC shell surrounding the NiSe2 nanocrystals acted as the primary conduction conduit for electron transport, while the self-supporting rGO–CNT framework served as a secondary pathway for consecutive electron transfer besides enhancing the structural robustness. Further, the polar NiSe2 nanocrystals offered numerous chemisorption sites for effectively capturing polysulfides, thus minimizing the shuttling effect and increasing active material utilization. The Li–S cell exhibited improved rate performance (till 4.0C) and excellent cycling stability (1000 cycles at 2.0C, average capacity decay rate of 0.04% per cycle). Even at severe cell parameters (effective S content = 74%, S loading = 4.5 mg cm−2, and electrolyte/sulfur = 5.7 µL mg−1), the cells delivered a stable rate performance and long-term cycling (400 cycles at 0.1C, average decay rate of 0.10% per cycle). We believe the nanostructure design strategy that we developed for this study could spur the development of more enduring and practical Li–S battery technology.

Blossoming of Multivalent Iron Phosphate Microplatelets Grown on Multiwall Carbon Nanotube Frameworks: Investigation of Supercapacitive Performance through Symmetric and Asymmetric Configurations

Blossoming of Multivalent Iron Phosphate Microplatelets Grown on Multiwall Carbon Nanotube Frameworks: Investigation of Supercapacitive Performance through Symmetric and Asymmetric Configurations

Construction of self-supporting macro-porous MnO@CNT anode for stable Li-ion battery

Nano-structure design and carbonous coupling are the most popular strategies to tackle the shortcomings of MnO-based anode materials. Herein, a nano-hybrid MnO anode is constructed with a self-supported carbon nanotube (CNT) framework interlacing MnO nanoparticles, denoted as MnO@CNT. The CNT can spontaneously agglomerate and form a self-supported macro-porous MnO@CNT sphere with interconnected CNT framework and abundant inner channels, which is beneficial for e− transport, Li+ conduction, and kinetics propulsion. The macro-porous structure delivers abundant interior volume to limit the outer expansion of the MnO@CNT anode, which effectively improves the solid electrolyte interface (SEI) stability, particle integrity, and cycling stability. Excellent cycling stability of over 750 cycling life and over 99% Coulombic efficiency can be achieved by the MnO@CNT anode, which is demonstrated to be closely related to the multi-functionalities of the hybrid structure. Therefore, our work provides an effective design idea and mechanism investigation for the high-capacity manganese oxide-based anodes.

Crystalline Nanodomains at Multifunctional Two-Dimensional Liquid–Metal Hybrid Interfaces

Two-dimensional (2D) liquid–metal (LM) heterointerfaces with their tunable physicochemical characteristics are emerging platforms for the development of multifunctional hybrid nanostructures with numerous functional applications. From this perspective, the functionalization of LM galinstan nanoparticles (NPs) with crystalline nanodomains is a promising approach toward the synthesis of novel 2D hybrid LM heterointerfaces with unprecedented properties. However, the decoration of LM heterointerfaces with desired nanocrystalline structures is a challenging process due to simultaneous and intensive interactions between liquid–metal-based structures and metallic nanodomains. The present study discloses a facile and functional method for the growth of crystalline nanodomains at LM heterointerfaces. In this sonochemical-assisted synthesis method, acoustic waves provide the driving force for the growth of ultra-fine crystalline nanodomains on the surface of galinstan NPs. The galinstan NPs were initially engulfed within carbon nanotube (CNT) frameworks, to prevent intensive reactions with surrounding environment. These CNT frameworks furthermore separate galinstan NPs from the other products of sonochemistry reactions. The following material characterization studies demonstrated the nucleation and growth of various types of polycrystalline structures, including Ag, Se, and Nb nanodomains on 2D heterointerfaces of galinstan NPs. The functionalized galinstan NPs showed tunable electronic and photonic characteristics originated from their 2D hybrid interfaces.

A three-dimensional interconnected molybdenum disulfide/multi-walled carbon nanotubes cathode with enlarged interlayer spacing for aqueous zinc-ion storage

Layered molybdenum disulfide (MoS2) shows tremendous prospect as cathode material for aqueous zinc-ion batteries (AZIBs) due to the two-dimensional zinc ions (Zn2+) diffusion channels and tunable interlayer spacing. However, it is subjected to sluggish insertion/extraction kinetics, inferior electronic conductivity and inadequate active capacities. Herein, a three-dimensional (3D) interconnected MoS2/multi-walled carbon nanotubes (MWCNTs) framework is proposed to address these issues. Importantly, the MWCNTs cores offer interconnection routes for fast electrons and zinc ions transport, the expanded spacing of MoS2 interlayer with 1.05 nm can facilitate rapid Zn2+ intercalation/extraction, and the confined MoS2 layers in inner MWCNTs can mitigate the agglomeration and restacking of MoS2 nanosheets. Benefitting from the confined structural configuration, sufficient active surface and 3D structural stability, the MoS2/MWCNTs as AZIBs cathode delivers a large initial reversible capacity of 218.3 mAh/g and high coulombic efficiency of 78.2 % at 0.1 A/g. Additionally, the 3D interconnected cathode maintains nearly intact structure after a fierce galvanostatic charge/discharge process, resulting in large retained capacities of 126.3 mAh/g at 1 A/g after 650 cycles and 101.1 mAh/g at 3 A/g after 1000 cycles. This work offers a novel strategy for the structure design of two-dimensional materials to develop high-performance cathodes for AZIBs.

Pore-controlled carbon nanotube sheet anodes for proton/anion-exchange membrane water electrolyzers

The commercialization of proton/anion-exchange membrane water electrolyzers (PEMWEs/AEMWEs) requires the development of high-performance and durable anodes. Herein, pore-controlled electrodes (C@PCEs) that incorporate carbon nanotube sheets with square pores and catalyst nanoparticles are designed. Ir and NiFe catalysts, which promote the oxygen evolution reaction under acidic and alkaline conditions, respectively, are applied in PEMWEs and AEMWEs. The C@PCEs have higher catalytic activities than the corresponding conventional densely packed electrodes (C@DPEs). Additionally, the PEMWEs and AEMWEs with C@PCEs exhibit improved performance with reduced overpotentials compared to those with C@DPEs. This enhancement in performance is ascribed to the pore structure of the C@PCEs, in which the electrocatalyst is well dispersed without agglomeration, thus increasing the electrochemical surface area. In addition, the highly conductive and porous carbon nanotube framework promotes electron and mass transfer. These results demonstrate that the C@PCE design is promising for anodes in both PEMWEs and AEMWEs.