1D Carbon Nanotubes Research Articles

High-performance multifunctional (Hf 0.2Nb 0.2Ta 0.2Ti 0.2Zr 0.2)C high-entropy ceramic reinforced with low-loading 3D hybrid graphene–carbon nanotube

There has been growing interest in the high-entropy ceramic (HEC) recently owing to its tailorable compositions and microstructures, versatile properties, together with promising structural and functional applications. However, inferior fracture toughness (<i>K</i>_IC) and damage tolerance restricted many practical applications of the HEC. Herein, we addressed this challenge by incorporating a three-dimensional graphene–carbon nanotube (3D G–CNT) as toughening agent in (Hf_0.2Nb_0.2Ta_0.2Ti_0.2Zr_0.2)C. The resulting enhanced 3D G–CNT/(Hf_0.2Nb_0.2Ta_0.2Ti_0.2Zr_0.2)C featured an outstanding toughness of 8.23 MPa·m^1/2, while remaining superior strength (763 MPa) and hardness (24.7 GPa). An ultralow friction coefficient (0.15) coupled with an ultralow wear rate (<i>w</i>, 2.6×10⁻⁷ mm³/(N·m)) in the 3D G–CNT/(Hf_0.2Nb_0.2Ta_0.2Ti_0.2Zr_0.2)C was obtained primarily as a function of lubricating scrolls, in which two-dimensional (2D) graphene acted as a tribolayer, and one-dimensional (1D) carbon nanotubes acted as nano ball bearings embedded inside. Strikingly, the 3D G–CNT/(Hf_0.2Nb_0.2Ta_0.2Ti_0.2Zr_0.2)C exhibited rather low thermal conductivity (<i>κ</i>) yet excellent electrical conductivity (<i>σ</i>, 1.3×10⁶ S/m) in comparison with the pure (Hf_0.2Nb_0.2Ta_0.2Ti_0.2Zr_0.2)C. This study provided great potential for maximizing the physical and functional properties of the HEC for various applications.

Construction of multi-dimensional NiCo/C/CNT/rGO aerogel by MOF derivative for efficient microwave absorption

The development of high-performance microwave absorption materials is currently imperative in order to solve the problem of electromagnetic pollution. Herein, we successfully obtained a multi-dimensional graphene-based aerogel (NiCo/C/CNT/rGO aerogel) decorated with one-dimensional carbon nanotubes (CNTs) and metal-organic framework (MOF) derivatives. The introduction of rGO aerogel significantly modifies the phase composition (NiCo/C/CNT and rGO) and hierarchical structure (1D CNT, 3D NiCo/C/CNT and rGO aerogel) of the composite, resulting in a multi-dimensional gradient, defects, heterogeneous interfaces, and superior microwave absorption properties. The optimum electromagnetic wave absorption performance of −58.8 dB is achieved at a filler loading of 20 wt%, with a thickness of 1.8 mm and an effective absorption bandwidth of 7.6 GHz, covering the entire Ku-band. The excellent electromagnetic wave absorption performance can be attributed to the synergistic effect of impedance matching, electromagnetic attenuation capability, unique multi-dimensional porous structure, abundant defects and interfaces. In summary, the present work provides a novel approach for the synthesis of multi-dimensional lightweight magnetic/dielectric microwave absorbers.

The role of selenium vacancies functionalized mediator of bimetal (Co, Fe) selenide for high-energy–density lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries are currently only in the basic research stage and have not been commercialized, which is mainly affected by the poor conductivity of sulfur/lithium sulfide (S/Li2S), volume expansion effect of sulfur and the shuttle effect of lithium polysulfides (LiPSs). Herein, a three dimensional (3D) carbon nanotubes (CNTs) decorated cubic Co9Se8−x/FeSe2−y (0 ＜ x ＜ 8, 0 ＜ y ＜ 2) composite (Co9Se8−x/FeSe2−y@CNTs) is developed, and used as the functionalized mediator on polypropylene (PP) in Li-S batteries. Benefiting from the good electrical conductivity, large number of Se vacancies and the triple block/adsorption/catalytic effects of Co9Se8−x/FeSe2−y@CNTs, the cell with Co9Se8−x/FeSe2−y@CNTs//PP modified separator delivers a high reversible capacity (1103.5 mA h g−1) at 1C after three cycles activation at 0.5C and remains 446 mA g h−1 after 750 cycles with a 0.08% capacity decay rate each cycle. Moreover, at 0.2C, a high areal capacity of 3.63 mA h cm−2 after 100 cycles with a high sulfur loading of 4.1 mg cm−2 is obtained. The in-situ XRD tests revealing the transition path of α-S8 → Li2S → β-S8 during the first charge–discharge process, then β-S8 → Li2S → β-S8 conversion reaction in the next cycles, and firstly determine the sulfur-selenide active intermediates (Se1.1S6.9) during cycles. The work provides a new insight into the development of bimetallic selenide composites by defect engineering with highly adsorptive and catalytic properties for Li-S batteries.

Biomimetic vertically aligned aerogel with synergistic photothermal effect enables efficient solar-driven desalination

Taking sustainable solar energy for efficient rapid clean water production is eagerly desired to overcome the water shortage issue. However, great challenges remain in constructing short water transport channels and enhancing sunlight utilization efficiency. Herein, a biomimetic solar-driven interfacial evaporator with rapid water transport and high photothermal conversion efficiency inspired by natural-trees was successfully developed, via engineer vertically aligned hydrophilic sodium alginate (SA) aerogels while hierarchically assembled MXene interwoven carbon nanotube (CNT) networks as micro/nano light absorb layer. Due to the synergistic photothermal effect between 2D MXene nanosheets and 1D CNT with multiple reflective nanostructure and strong light-absorption over a broad spectrum, and super-hydrophilic SA with highly oriented water transport channels, which enables fast water/vapor transport while utilizing solar energy efficiently. Vertically aligned aerogel exhibits an excellent water evaporation performance which as high as 2.416 kg m−2 h−1 (deducting dark conditions) and remarkable solar energy utilizing efficiency of 90.56 %, which are extremely higher than that of most reported desalination devices. Furthermore, the solar-driven evaporator also exhibits strong antibacterial properties and long-term operation stability. The biomimetic vertically aligned aerogel with excellent water evaporation and light utilization efficiency holds great promise for high-performance water purification and desalination applications. Synopsis statementResearch on the rapid clean water production from wastewater/seawater with high solar energy utilization efficiency has become a hot topic, and solar-driven desalination offers a sustainable solution to meet water demands. This study reports a biomimetic solar-driven interfacial evaporator with oriented water transport nanochannel and multi-reflective solar absorber for efficient clean water production.

Triphenylamine-based covalent triazine framework @ carbon nanotube complex: efficient photogenerated charges migration for metal free photocatalytic Cr(VI) reduction

Photocatalytic hazardous hexavalent chromium Cr(VI) reduces to nontoxic trivalent chromium Cr(III) by metal free catalytic system under visible light irradiation is a promising method to harness Cr(VI) pollution. However, the rate-determining step for these systems is still charge separation and transport from semiconductor to the surface active site due to high exciton binding energy and transport Schottky barrier. Herein, we present a novel composite catalyst by situ growth of two-dimensional triphenylamine-based covalent triazine framework (TACTF) semiconductor with one-dimensional (1D) carbon nanotube (CNT) electronic conductivity mediator. The resultant TACTF@CNT complex exhibits a lower Schottky barrier, which improves lateral charge transport and interlayer exciton dissociation though interconnections TACTF layers with CNT, assuring high efficiency of photogenerated charges transfer from TACTF semiconductor to the surface active site for subsequent photocatalytic Cr(VI) reduction. The TACTF@CNT shows an excellent photocatalytic activity for Cr(VI) reduction, and 100 % removal of Cr(VI) was observed under visible light irradiation for 2 h, which is remarkably superior to those of TACTF, CNT and their physical mixture.

Oxygenated Hydrocarbons from Catalytic Hydrogenation of Carbon Dioxide

Once fundamental difficulties such as active sites and selectivity are fully resolved, metal-free catalysts such as 3D graphene or carbon nanotubes (CNT) are very cost-effective substitutes for the expensive noble metals used for catalyzing CO2. A viable method for converting environmental wastes into useful energy storage or industrial wealth, and one which also addresses the environmental and energy problems brought on by emissions of CO2, is CO2 hydrogenation into hydrocarbon compounds. The creation of catalytic compounds and knowledge about the reaction mechanisms have received considerable attention. Numerous variables affect the catalytic process, including metal–support interaction, metal particle sizes, and promoters. CO2 hydrogenation into different hydrocarbon compounds like lower olefins, alcoholic composites, long-chain hydrocarbon composites, and fuels, in addition to other categories, have been explained in previous studies. With respect to catalyst design, photocatalytic activity, and the reaction mechanism, recent advances in obtaining oxygenated hydrocarbons from CO2 processing have been made both through experiments and through density functional theory (DFT) simulations. This review highlights the progress made in the use of three-dimensional (3D) nanomaterials and their compounds and methods for their synthesis in the process of hydrogenation of CO2. Recent advances in catalytic performance and the conversion mechanism for CO2 hydrogenation into hydrocarbons that have been made using both experiments and DFT simulations are also discussed. The development of 3D nanomaterials and metal catalysts supported on 3D nanomaterials is important for CO2 conversion because of their stability and the ability to continuously support the catalytic processes, in addition to the ability to reduce CO2 directly and hydrogenate it into oxygenated hydrocarbons.

1D/3D rambutan-like Mott–Schottky porous carbon polyhedrons for efficient tri-iodide reduction and hydrogen evolution reaction

Realizing rapid electron transfer and mass diffusion in virtue of interface regulation and nanostructure design is an effective strategy to augment the catalytic activity of carbon materials but still a significant challenge. Herein, a novel frontier 1D/3D rambutan-like Mott-Schottky-type nitrogen-doped carbon polyhedron (NiCo-NCP/CNT) consisting of nickel/cobalt species and a 3D porous carbon skeleton intertwined with 1D carbon nanotubes (CNT) is controllably fabricated by rationally utilizing Co/Zn bimetallic-organic frameworks and nickel ions. The photovoltaic device fabricated with NiCo-NCP/CNT electrocatalyst achieves a power conversion efficiency of 8.75%, which is superior to that of conventional Pt electrodes (7.25%). When the NiCo-NCP/CNT electrocatalyst is employed as the cathode for water splitting under alkaline conditions, an overpotential as low as 63 mV is demonstrated at a current density of 10 mA·cm−2. The improved work function (from 4.65 to 4.59 eV) proves that introducing NiCo favors regulating electronic states and optimizing energy level, which could induce more robust self-driven electron transfer at the Mott-Schottky interface. The proposed nickel adsorption-sintering strategy effectively promotes electron/mass transfer capability simultaneously in carbon-based Mott-Schottky catalysts and paves the way for developing low-cost and high-performance electrocatalysts in electrocatalytic fields.

Efficient charge separation and transfer in a one-dimensional carbon nanotube/tungsten oxide p-n heterojunction composite for solar energy conversion.

Efficient and cost-effective photocatalysts for solar energy conversion represent a rapidly advancing and compelling area of research. In our study, we employed theoretical calculations to design a novel composite material consisting of a one-dimensional (1D) carbon nanotube (CNT) and tungsten oxide (W18O49) p-n heterojunction. This composite material was successfully synthesized using a straightforward solvothermal method, and we thoroughly investigated the charge separation and transfer mechanism. Our findings revealed that the composite material exhibited a superior photocurrent response. Notably, the CNTs/W18O49-2 sample demonstrated a significantly higher photocurrent under both AM 1.5G and infrared light irradiation, outperforming the individual components under AM 1.5G by a substantial factor of 30. This remarkable enhancement in performance can be attributed to the efficient charge separation and transfer facilitated by the built-in electric field created at the interface through the p-n heterojunction. Our study introduces a pioneering integration of CNTs and 1D tungsten oxide, resulting in a composite structure with a p-n heterojunction-a concept that has not been extensively explored previously. The results confirmed the formation of this unique one-dimensional structure and a p-n heterojunction, which has outstanding properties for various applications. These findings provide a robust foundation for the design of photocatalytic interfaces and offer a fresh approach to the development of high-performance photocatalysts.

A novel catalyst derived from Co-ZIFs to grow N-doped carbon nanotubes for all-solid-state supercapacitors with high performance.

Carbon nanotubes (CNTs) have been widely used as electrode materials for electrochemical energy storage devices (e.g., supercapacitors) due to their excellent chemical and physical properties. However, conventional approaches (e.g., electron-beam vapor deposition and atomic layer deposition) to fabricate catalysts for the growth of CNTs are complex and demand high energy consumption. Herein, we report a facile method to synthesize catalysts derived from cobalt-containing zeolitic imidazolate frameworks (Co-ZIFs), which is exploited to in situ construct the three-dimensional (3D) CNT hybrid materials for all-solid-state supercapacitors. In brief, Co-ZIFs with a controllable structure is first grown on the inner porous surface of carbon foams pyrolyzed from commercial melamine foams, followed by thermal annealing and chemical vapor deposition to grow CNTs, achieving 3D free-standing CNT-based hybrids. The well-distributed Co-ZIFs in the carbon foam enable the grown CNTs with uniform structures and morphologies. Using the fabricated CNT-based hybrid as electrodes, the assembled all-solid-state supercapacitors show a high specific capacitance of 19.4 mF cm-2 at a current density of 0.5 mA cm-2, which could be further optimized to as high as 871.8 mF cm-2 by incorporating the pseudocapacitive material of manganese dioxide in CNT-based hybrids. This study provides a facile solution approach to fabricate the catalyst for the growth of a CNT inner porous substrate; the resultant 3D free-standing hybrids could be used as efficient electrodes for high-performance energy storage devices beyond supercapacitors.

Dual-Silica Template-Mediated Synthesis of Nitrogen-Doped Mesoporous Carbon Nanotubes for Supercapacitor Applications.

1D carbon nanotubes have been widely applied in many fields, such as catalysis, sensing and energy storage. However, the long tunnel-like pores and relatively low specific surface area of carbon nanotubes often restrict their performance in certain applications. Herein, a dual-silica template-mediated method to prepare nitrogen-doped mesoporous carbon nanotubes (NMCTs) through co-depositing polydopamine (both carbon and nitrogen precursors) and silica nanoparticles (the porogen for mesopore formation) on a silica nanowire template is proposed. The obtained NMCTs have a hierarchical pore structure of large open mesopores and tubular macropores, a high specific surface area (1037 m2 g-1 ), and homogeneous nitrogen doping. The NMCT-45 (prepared at an interval time of 45min) shows excellent performance in supercapacitor applications with a high capacitance (373.6 F g-1 at 1.0 A g-1 ), excellent rate capability, high energy density (11.6W h kg-1 at a power density of 313W kg-1 ), and outstanding cycling stability (98.2% capacity retention after 10000 cycles at 10 A g-1 ). Owing to the unique tubular morphology, hierarchical porosity and homogeneous N-doping, the NMCT also has tremendous potential in electrochemical catalysis and sensing applications.

Zero to Three Dimension Structure Evolution from Carbon Allotropes to Phosphorus Allotropes

AbstractAs the promising and highly‐focused materials after silicon, carbon, and phosphorus promote the development of nanotechnology due to its allotropes with unique structures and properties. The carbon allotropes of 0D fullerene, 1D carbon nanotube, and 2D graphene stimulate the investigation of structures, synthesis, properties, and further applications of carbon nanomaterials. Analogous to carbon, phosphorus is demonstrated to have a rich phase diagram. 0D phosphorus fullerenes, 1D phosphorus nanotubes and fibrous red phosphorus, and recently 2D black phosphorene and violet phosphorene have unique structures analogous to carbon fullerene, carbon nanotube, and graphene, is developed. The photoelectronic properties and further applications of the phosphorus allotropes as semiconductors, energy storage materials, biomaterials, and sensors are also investigated. Great efforts are dedicated to studies of the synthesis, structure, and properties of carbons and phosphorus. However, there is no systematic review of the structure of phosphorus allotropes compared to carbon allotropes. Herein, the structures along with possible future perspective of carbon and phosphorus allotropes review and compare in this work based on the classification of different dimensions.

3D Printable One‐Part Carbon Nanotube‐Elastomer Ink for Health Monitoring Applications

Abstract3D printing of conductive elastomers is a promising route to personalized health monitoring applications due to its flexibility and biocompatibility. Here, a one‐part, highly conductive, flexible, stretchable, 3D printable carbon nanotube (CNT)‐silicone composite is developed and thoroughly characterized. The one‐part nature of the inks: i) enables printing without prior mixing and cures under ambient conditions; ii) allows direct dispensing at ≈100 µm resolution printability on nonpolar and polar substrates; iii) forms both self‐supporting and high‐aspect‐ratio structures, key aspects in additive biomanufacturing that eliminate the need for sacrificial layers; and iv) lends efficient, reproducible, and highly sensitive responses to various tensile and compressive stimuli. The high electrical and thermal conductivity of the CNT‐silicone composite is further extended to facilitate use as a flexible and stretchable heating element, with applications in body temperature regulation, water distillation, and dual temperature sensing and Joule heating. Overall, the facile fabrication of this composite points to excellent synergy with direct ink writing and can be used to prepare patient‐specific wearable electronics for motion detection and cardiac and respiratory monitoring devices and toward advanced personal health tracking and bionic skin applications.

Adsorption characteristics of six bisphenol compounds on magnetic three-dimensional nitrogen-doped carbon nanomaterials and their use in effervescent reaction-assisted dispersive microextraction

Herein, we successfully prepared magnetic Co/Ni-based N-doped 3D carbon nanotubes and graphene nanocomposites (CoNi@NGC) using a simple high-temperature calcination method. The CoNi@NGC nanocomposites were used as adsorbents to study their adsorption performances and underlying kinetic mechanisms for six types of bisphenol compounds (BPs) in water. They were also used as extractants, and acid-base effervescent tablets were used to enhance extractant dispersion with the aid of vigorous CO2 bubbling. Thus, a novel pretreatment method was developed, denoted effervescent reaction-assisted dispersive solid-phase microextraction (ER-DSM), which was combined with high performance liquid chromatography-fluorescence detection (HPLC-FLD) to rapidly quantify trace-level BPs in several drinks. The morphology and structure of the CoNi@NGC adsorbent were characterized in detail using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), N2 adsorption and desorption (BET-BJH), X-ray photoelectron spectroscopy (XPS), and vibrating sample magnetometry (VSM). The CoNi@NGC nanocomposites were successfully doped with N and exhibited large specific surface areas (109.42 m2/g), abundant pores, and strong magnetic properties (17.98 emu/g).Key parameters were rigorously optimized to maximize the adsorption performance of CoNi@NGC, including adsorbent dosage, solution pH, temperature, and time. Under the constant conditions of pH=7, 5 mg of CoNi@NGC, initial BP concentrations of 5 mg/L, and 5 min of shaking at 298 K, the adsorption percentages of bisphenol M (BPM) and bisphenol A (BPA) reached respective maxima of 99.01% and 98.21%. Remarkably, those of bisphenol Z (BPZ), BPA, and BPM reached almost 100% after 90 min. The adsorption between the BPs and CoNi@NGC was mainly governed by hydrogen bonds, electrostatic interactions, and π-π conjugation. The entire adsorption process was consistent with Freundlich adsorption and a quasi-second-order kinetic equation, representing spontaneous adsorption. Via integration with HPLC-FLD, ER-DSM was used to rapidly extract and analyze trace-level BPs in six types of boxed drinks. Critical factors were optimized individually, including the type of eluent and elution time and volume, which influenced the enrichment effect. Under the optimized extraction conditions (pH=7, 5 mg CoNi@NGC, elution with 2 mL acetone for 6 min), the limits of detection and quantification of the novel extraction method were 0.06-0.20 and 0.20-0.66 μg/L, respectively. The intra- and inter-day precisions spanned the ranges 1.44%-4.76% and 1.69%-5.36%, respectively, and the recoveries in the actual samples were in the range 82.4%-103.7%. Moreover, the respective residual levels of BPA and BPB in peach juice samples were 2.09 and 1.37 μg/L. Regeneration studies revealed that the CoNi@NGC adsorbent could be reused at least five times, which significantly reduced the cost of evaluation. In summary, compared to other methods, this method displays the advantages of a high sensitivity, rapid extraction, and environmental friendliness, thereby exhibiting considerable potential for use in conventional monitoring of trace-level BPs in food matrices.

Metal organic framework-derived hierarchical 0D/1D CoPC/CNTs architecture interlaminated in 2D MXene layers for superior absorption of electromagnetic waves

Nowadays, exploring effective electromagnetic wave (EMW) absorbing materials with ultrathin thickness, lightweight, broad absorption bandwidth, and robust absorption capability is crucial to solve EMW pollution issues. Ti3C2Tx is a potential candidate for effective EMW absorbing materials by virtue of its low density, excellent electrical conductivity, high specific surface area, and tunable terminal groups. However, the intrinsic attenuation mechanisms of single dielectric absorbers are limited for practical requirements. Herein, 0D/1D/2D architecture of CoPC/CNTs@MXene hybrids with 0D cobalt nanoparticles supported on porous carbon, 1D carbon nanotubes and 2D Ti3C2Tx nanosheets have been conceptualized and fabricated successfully. By pyrolyzing bimetallic ZnCo-MOF at 800 °C, a 0D/1D hierarchical CoPC/CNTs sample was initially produced, subsequently interlaminated between the Ti3C2Tx matrix via electrostatic self-assembly to fabricate CoPC/CNTs@MXene (CCM) absorbers. The impedance matching properties was optimized by modifying the CoPC/CNTs content. Remarkably, CCM-20 hybrids achieved strong EMW absorption capability (reflection loss of −54.2 dB) at 5.56 GHz, and CCM-30 hybrids achieved ultrathin (1.8 mm) and a broad effective bandwidth (EAB) below − 10 dB (5.6 GHz), which is superior to the magnetic-dielectric hybrids with comparable components reported previously. The exceptional absorption capability can be attributed to the synergistic effects of interface polarizations and magnetic loss. The intricate construction of the 0D/1D/2D architecture facilitates the multiple reflections and scattering of EMW. This work provides an idea for fabricating MXene-based composites with remarkable electromagnetic properties and a broad absorption bandwidth for potential applications.

Au Nanorods on Carbon-Based Nanomaterials as Nanohybrid Substrates for High-Efficiency Dynamic Surface-Enhanced Raman Scattering.

Gold nanorods (AuNRs) with different aspect ratios were prepared by the seed-mediated growth method and combined with three carbon-based nanomaterials of multiple dimensions (i.e., zero-dimensional (0D) carbon black (CB), one-dimensional (1D) carbon nanotubes (CNTs), and two-dimensional (2D) graphene oxide (GO)). The AuNR/carbon-based nanomaterial hybrids were utilized in dynamic surface-enhanced Raman scattering (D-SERS). First, cetyltrimethylammonium bromide (CTAB) was used to stabilize and coat the AuNRs, enabling them to be dispersed in water and conferring a positive charge to the surface. AuNR/carbon-based nanomaterial hybrids were then formed via electrostatic attraction with the negatively charged carbon-based nanomaterials. Subsequently, the AuNR/carbon-based nanomaterial hybrids were utilized as large-area and highly sensitive Raman spectroscopy substrates. The AuNR/GO hybrids afforded the best signal enhancement because the thickness of GO was less than 5 nm, which enabled the AuNRs adsorbed on GO to produce a good three-dimensional hotspot effect. The enhancement factor (EF) of the AuNR/GO hybrids for the dye molecule Rhodamine 6G (R6G) reached 1 × 107, where the limit of detection (LOD) was 10-8 M. The hybrids were further applied in D-SERS (detecting samples transitioning from the wet state to the dry state). During solvent evaporation, the system spontaneously formed many hotspots, which greatly enhanced the SERS signal. The final experimental results demonstrated that the AuNR/GO hybrids afforded the best D-SERS signal enhancement. The EF value for R6G reached 1.1 × 108 after 27 min, with a limit of detection of 10-9 M at 27 min. Therefore, the AuNR/GO nanohybrids have extremely high sensitivity as molecular sensing elements for SERS and are also very suitable for the rapid detection of single molecules in water quality and environmental management.

Top-Down Production of Sustainable and Scalable Hemicellulose Nanocrystals.

Polysaccharide nanocrystals have led to the development of multifunctional and sustainable materials, but most are glucose-based carbohydrates derived from valuable natural sources. Here, we present a top-down strategy that enables one, for the first time, to isolate xylose-based hemicellulose nanocrystals from available industrial biowastes. By leveraging the selective oxidation of alkaline periodate, as high as 34 wt % solid yield is accessible. The hemicellulose nanocrystals exhibit platelet-like shapes (10-20 nm thickness, 30-80 nm wide), crystalline features, and superior dispersibility in water. We also showcase their successful interface applications for one-dimensional (1D) carbon nanotube (CNT) nanoinks and two-dimensional (2D) transition-metal dichalcogenide (TMD) nanozymes, which are comparable to the traditional cellulose nanocrystals. The scalable, low-cost, and sustainable hemicellulose nanocrystals can be envisioned to provide an alternative for glucose-based polysaccharide nanocrystals, as well as hold promise for the high-value utilization of biowastes.

Core-shell structure and 3D CNTs networks promote Si@Cu nanoparticle anodes with enhanced reversible capacity and cyclic performance for Li-ion batteries

With the rapid growth of demand for energy storage technology in various industries, it is particularly urgent to develop battery systems with higher energy density. Among the candidates, silicon (Si) has a high lithium storage capacity as anode material, but its large volume variation and low electron and ion conductivity prevent it from being diffusely used in multiple fields, such as large-scale energy storage systems. In this work, we complement the advantages of Si, metal copper (Cu), and carbon nanotubes (CNTs) to synthesize Si@Cu nanoparticles with core-shell structures encapsulated in a 3D CNTs network (Si@Cu/CNTs). The coating of Cu and the 3D CNTs network help to slow down the volumetric expansion of Si during the cycle and the exfoliation and pulverization which are caused by volume expansion. Meanwhile, the synergy of the highly conductive metal Cu and 3D CNTs network provides fast migration channels for ions/electrons, which is advantageous for the capacity at high current densities. The synergy of Cu and 3D CNTs network also avoids the immediate between the electrolyte and the Si nanoparticles, which is beneficial to maintaining the integrity of the SEI film, thus enhancing the electrochemical performance of the material. Si@Cu/CNTs exhibit a capacity of 2107.5 mAh g−1 after 50 cycles at a current density of 100 mA g−1, with a capacity retention rate of 74.06%. Si@Cu/CNTs also have favourable rate capability, with a capacity of 2338.6 mAh g−1 and a capacity retention rate close to 80% when the current density drops to 100 mA g−1. This work presents a novel idea for the modification of Si materials.

A novel electro-synthesis of hierarchical Ni–Al LDH nanostructures on 3D carbon nanotube networks for hybrid-capacitors

Despite the advantages of fiber-shaped supercapacitors (FSCs) in powering wearable electronics, the low energy density dramatically hinders their practical application. Asymmetric configuration design especially with pseudocapacitive materials is an effective solution due to the extended voltage window and large pseudocapacitance. In this paper, a flexible asymmetric FSC is designed, which uses carbon fiber (CF) as the substrate, multi-layer alternating Ni–Al layered double hydroxide/mono-dispersed carbon nanotube (CNT) coaxial layer ([Ni–Al LDH-x/CNT-y]@CF) as the positive electrode material, and tremella-derived activated carbon@CF (TDC-z) as negative electrode material. The 3D Ni–Al LDH/CNT network can realize high-quality loading, rapid electron transfer, effective ion diffusion, and mechanical stress release. The obtained [Ni–Al LDH-2/CNT-2]@CF composite has a large specific capacitance of 1800 F g−1 and high capacity retention of 65.8% at a current density of 10 A g−1. Based on that, the resulting Ni–Al LDH-2/CNT-2]@CF//TDC-800@CF achieves a remarkable energy density of 35.6 Wh kg−1, a power density of 7531.90 W kg−1, and superior cycling stability of 124.8% over 5000 cycles at a current density of 10 A g−1. These encouraging results indicate that our hybrid FSC has clear potential as a wearable/flexible energy storage device.

Carbon nanotube-vertical edge rich graphene hybrid sponge as multifunctional reinforcements for high performance epoxy composites

Thermal management materials with excellent electromagnetic interference (EMI) shielding performance have attracted research interest in the field of modern electronic devices. Herein, vertical edge rich graphene (VG) was in-situ grafted on the carbon nanotube (CNT) sponge to create connective 3D hybridized carbon skeleton with covalent bonding, then CNT-VG/epoxy composites were constructed to meet the needs of multifunctional application. Impressively, mainly owing to the connectivity of 3D CNT sponge, the conduction ability of interfaces and the defect-rich structure of VG, the obtained CNT-VG/epoxy composites possessed an enhanced EMI shielding effectiveness of 46.9 dB with a thickness of 1 mm and an improved thermal conductivity of 2.23 W m−1 K−1 which contributes to superior thermal management capability. In addition, the excellent structural design also increases the flexural strength by 349.39% compared to pure epoxy resin, achieving a flexural strength of 275.32 MPa and a work of fracture of 9956.98 kJ m−3. The novel multifunctional CNT-VG/epoxy composites with enhanced mechanical property show a bright application prospect in next-generation electronic devices.

Regulating electronic structure by Mn doping for nickel cobalt hydroxide nanosheets/carbon nanotube to promote oxygen evolution reaction and oxidation of urea and hydrazine

Electrocatalytic water splitting is one of the direct and efficient means to yield high-purity hydrogen, but it still exists some challenges in addition to the sluggish anodic oxygen evolution reaction (OER). Constructing highly-efficient electrocatalysts with superior properties plays an essential role in industrial hydrogen production. In this work, a novel electrocatalyst with a distinctive three-dimensional (3D) structure is constructed by intertwining two-dimensional (2D) hexagonal NiCo hydroxide nanosheets (NiCo HNS) with one-dimensional (1D) carbon nanotubes (CNTs). The strategy of elemental doping engineering is employed to further enhance the catalytic performance. The as-fabricated composite of Mn-doped nickel cobalt hydroxide nanosheets intertwined with CNTs (1.5Mn-NiCo HNS/CNT) delivers superior OER electrocatalytic performance, which requires an overpotential of only 239 mV to achieve the current density of 10 mA cm−2 in 1 M KOH. Compared to NiCo HNS/CNT, the 1.5Mn-NiCo HNS/CNT electrocatalyst exhibits characteristics of improved electrical conductivity, larger electrochemical active surface area (ECSA), and faster reaction kinetics due to Mn doping. Density functional theory (DFT) calculations revealed that the adsorption of OH– during the first step of OER process was the potential determining step for the Mn substituted Co sites, and the Mn substituted Co sites were the optimum reactive sites that determined the OER performance of the 1.5Mn-NiCo HNS/CNT. Mn doping was proved beneficial to optimize the reaction path and decrease the reaction kinetics energy barrier. The addition of urea or hydrazine into the electrolyte directly decreases the energy consumption and realize their decomposition as pollutants in industrial and agricultural wastewater.