Carbon Nanowires Research Articles

MoS2 encapsulated in N-doped mesoporous carbon nanowires as high-rate anode for K-ion capacitors

The main challenge for the emerging K-ion capacitors (KICs) is designing high-rate performance anode to match the fast kinetics of the cathode. In this work, we encapsulated MoS2 nanosheets in N-doped mesoporous carbon nanowires (MoS2@MCNWs) by dual-templating method as high-rate anode. After the performance was optimized with respect to MoS2 content, the preferred MoS2@MCNWs-2 (25 wt% MoS2) electrode shows a superior rate capability (89.2 mAh g−1 at 10 A g−1). Furthermore, the constructed KIC demonstrates superior energy/power density (Max. 106.5 Wh kg−1/9703.9 W kg−1) with excellent cycling stability (97.6% of initial capacitance after 6000 cycles at 1 A g−1). The good electrochemical properties arise mainly from the one-dimensional (1D) nanostructure that can facilitate the transportation of electrons, the opened ordered mesopores on the carbon nanowires that can endow the rapid K-ion/electrolyte diffusion, and the ultrafine MoS2 nanosheets embedded in carbon nanowires that can offer a lot of active sites. Furthermore, the doped N in carbon can afford additional adsorption sites for discharge products, promoting the durability of the electrode, which is confirmed by density function theory (DFT) calculations. This delicate design could offer a new avenue for the development of 1D-based anode with high-rate performance in metal-ion capacitors.

Carbon nanowires made by the insertion-and-fusion method toward carbon-hydrogen nanoelectronics.

Carbon nanowires (CNWs), long linear carbon chains encapsulated inside carbon nanotubes, exhibit sp hybridization characteristics as one of one-dimensional nanocarbon materials. The research interests on CNWs are accelerated by the successful experimental syntheses from the multi-walled to double-walled until single-walled CNWs recently but the formation mechanisms and structure-property relationships of CNWs remain poorly understood. In this work, we studied the insertion-and-fusion formation process of CNWs at an atomistic level using ReaxFF reactive molecular dynamics (MD) and density functional theory (DFT) calculations with particular focus on the hydrogen (H) adatom effects on the configurations and properties of carbon chains. The constrained MD shows that short carbon chains can be inserted and fused into long carbon chains inside the CNTs due to the van der Waals interactions with little energy barriers. We found that the end-capped H atoms of carbon chains may still remain as adatoms on the fused chains without C-H bond breaking and could transfer along the carbon chains via thermal activation. Moreover, the H adatoms were found to have critical effects on the distribution of bond length alternation as well as the energy level gaps and magnetic moments depending on the varied positions of H adatoms on the carbon chains. The results of ReaxFF MD simulations were validated by the DFT calculations and ab initio MD simulations. The diameter effect of the CNTs on the binding energies suggest that multiple CNTs with a range of appropriate diameters can be used to stabilize the carbon chains. Different from the terminal H of carbon nanomaterials, this work demonstrated that the H adatoms could be used to tune the electronic and magnetic properties of carbon-based electronic devices, opening up the door toward rich carbon-hydrogen nanoelectronics.

Activated carbon nanofiber nanoparticles incorporated electrospun polycaprolactone scaffolds to promote fibroblast behaviors for application to skin tissue engineering

The most widely used one-dimensional (1D) carbonaceous nanomaterials in tissue engineering are carbon nanotubes, either single or multiwalled. Other forms of 1D nanomaterials, such as carbon nanowires and carbon nanofibers, have been less explored for biomedical applications. Herein, we synthesized 1D-activated carbon nanofiber nanoparticles (ACNF NPs) from the polyacrylonitrile electrospun nanofibers by continuous processes like stabilization, alkali treatment, calcination, and grinding. Two different sets of ACNF NPs-containing electrospun polycaprolactone (PCL) nanofiber mats, viz. surface-modified NP-deposited mats (ACNF@PCL) and NP-incorporated mats (ACNF-PCL), were prepared to examine their potential as skin tissue engineering scaffolds. Raman spectra demonstrated that ACNF NPs exhibited graphitization degree with an ID/IG ratio of 1.05. Scanning electron microscopy (SEM) observations showed that ACNF NPs are sized 280 ± 100 nm by diameter and 565–3322 nm by length. The NPs concentrated above 30 μg/mL were found to exhibit toxicity with < 70% viability of NIH3T3 fibroblasts on 48 h. The ACNF-PCL nanofiber mats displayed better cell proliferation profile showing significant changes compared to PCL and ACNF@PCL mats on days 1, 3, and 5. Hence, we concluded that ACNF-PCL mats with less concentration of ACNF NPs have more potential to support cellular growth, ensuring its possible impact on skin tissue regeneration.Graphical Abstract

Nickel-Ion Activating Discarded COVID-19 Medical Surgical Masks for Forming Carbon-Nickel Composite Nanowires and Using as a High-Performance Lithium Battery Anode.

With the prevalence of COVID-19, wearing medical surgical masks has become a requisite measure to protect against the invasion of the virus. Therefore, a huge amount of discarded medical surgical masks will be produced, which will become a potential hazard to pollute the environment and endanger the health of organisms without our awareness. Herein, a green and cost-effective way for the reasonable disposal of waste masks becomes necessary. In this work, we realized the transformation from waste medical surgical masks into high-quality carbon-nickel composite nanowires, which not only benefit the protection of the environment and ecosystem but also contribute to the realization of economic value. The obtained composite carbon-based materials demonstrate 70 S m-1 conductivity, 5.2 nm average pore diameters, 234 m2 g-1 surface areas, and proper graphitization degree. As an anode material for lithium-ion batteries, the prepared carbon composite materials demonstrate a specific capacity of 420 mA h g-1 after 800 cycles at a current density of 0.2 A g-1. It also displays good rate performance and decent cycling stability. Therefore, this study provides an approach to converting the discarded medical surgical masks into high-quality carbon nanowire anode materials to turn waste into treasure.

Multi-size distributed Ni catalyst embedded in SiCxOy film by inverse microemulsion-precipitation method for ethanol steam reforming

Ni/SiCxOy catalysts with multi-size distribution of Ni particles, were prepared and supported on porous SiC ceramics by a combination of inverse microemulsion and precipitation methods, as reaction microchannels for ethanol steam reforming (ESR). The microstructure, phase composition, reduction performance, hydrogen production performance of ESR, and the type and growth of carbon deposition were investigated for Ni/SiCxOy catalysts. The Ni catalysts embedded in SiCxOy film with the appropriate amount of precipitant exhibited multi-size distribution and minimal particle size. The initial ethanol conversion rate and H2 selectivity of Ni/SiCxOy catalysts during ESR reaction were 100% and 75%, respectively, remaining 95% and 69.2% after 20 h, respectively. Raman and SEM results indicate that Ni/SiCxOy catalysts with appropriate amounts of precipitant tended to grow more loosely arranged carbon nanowires. The combination of inverse microemulsion and precipitation methods produced smaller and multi-size distributed Ni/SiCxOy catalysts with superior durability and hydrogen production performance in ESR reaction.

MOF-derived 3D interconnected amorphous carbon nanowire networks for robust lithium storage

MOF-derived amorphous carbon-based materials has exhibited great potential for lithium-ion batteries (LIBs) with exceptional gravimetric capacity cycle stability. However, it is a great challenge to realize morphology control during the transformation process from MOF to carbon derivatives for obtaining electrode materials with superior rate performance and capacity retention rate under long cycle and high current density. Herein, through combining rapid heat and linker removing processes, a 3D interconnected amorphous carbon nanowire networks with developed hierarchical pores were prepared from sub-micron brick-like crystal Al-MOF. The 3D amorphous carbon with high specific surface area can provide substantial active sites for lithium storage, the interconnected nanowire networks can facilitate fast electron conduction, and the developed hierarchical pores can promote ion transport; therefore, the 3D amorphous carbon electrode exhibits superior rate performance and delivers an capacity as high as 400 mAh/g under the current density of 1.0 A/g even after 1000 cycles with an ultra-high-capacity retention rate of 101.8%, considerably outperforming other carbon derivatives derived from different types of MOF. The effective preparation method for morphology control and superior lithium storage performance represents a critical step toward capturing the full potential of MOF-derived carbon electrode materials in practical LIBs applications.

Modulating Surface Electron Density of Heterointerface with Bio-Inspired Light-Trapping Nano-Structure to Boost Kinetics of Overall Water Splitting.

Herein, inspired by natural sunflower heads' properties increasing the temperature of dish-shaped flowers by tracking the sun, a novel hybrid heterostructure (MoS2 /Ni3 S2 @CA, CA means carbon nanowire arrays) with the sunflower-like structure to boost the kinetics of water splitting is proposed. Density functional theory (DFT) reveals that it can modulate the active electronic states of NiMo atoms around the Fermi-level through the charge transfer between the metallic atoms of Ni3 S2 and MoMo bonds of MoS2 to boost overall water splitting. Most importantly, the finite difference time domain (FDTD) could find that its unique bio-inspired micro-nano light-trapping structure has high solar photothermal conversion efficiency. With the assistance of the photothermal field, the kinetics of water-splitting is improved, affording low overpotentials of 96 and 229mV at 10mAcm-2 for HER and OER, respectively. Moreover, the Sun-MoS2 /Ni3 S2 @CA enables the overall alkaline water splitting at a low cell voltage of 1.48 and 1.64V to achieve 10 and 100mAcm-2 with outstanding catalytic durability. This study may open up a new route for rationally constructing bionic sunflower micro-nano light-trapping structure to maximize their photothermal conversion and electrochemical performances, and accelerate the development of nonprecious electrocatalysts for overall water splitting.

Atomic Pt anchored on hierarchically porous monolithic carbon nanowires as high-performance catalyst for liquid hydrogenation

Atomic Pt anchored on hierarchically porous monolithic carbon nanowires as high-performance catalyst for liquid hydrogenation

Synthesis of NiO/Nitrogen-Doped Carbon Nanowire Composite with Multi-Layered Network Structure and Its Enhanced Electrochemical Performance for Supercapacitor Application.

Multi-layered NiO nanowires linked with a nitrogen-doped carbon backbone grown directly on flexible carbon cloth (NiO/NCBN/CC) was successfully fabricated with a facile synthetic strategy. The NiO/NCBN/CC was further used as a binding-free electrode for flexible energy storage devices, showing a boosted performance including a high capacitance of 1039.4 F g−1 at 1 A g−1 and an 83.4% capacitance retention ratio. More importantly, after 1500 cycles, the capacitance retention can achieve 72.5% at a current density of 20 A g−1. The excellent electrochemical properties of the as-prepared NiO/NCBN/CC are not only attributed to the multi-layered structure that can help to tender unimpeded channels and accommodate the electrolyte ions around the electrode interface during the charge–discharge process, but is also due to the link between the NiO and N-doped carbon backbone and the nitrogen doping on the carbon substrate, which results in extra defects on the surface that could boost the interfacial electron transfer rate of the electrode.

Nitrogen-doped carbon layer on cellulose derived free-standing carbon paper for high-rate supercapacitors

Free-standing porous carbon have risen to prominent electrode materials for high-rate solid-state supercapacitors, yet they are still plagued by uneconomical petrochemical feedstocks, tedious slurry-casting processes, and suboptimal performance. Herein, a dual‐strategy of combining free-standing nitrogen-doped carbon nanowire array coating and pore engineering is designed to boost the performance of cellulose-derived carbon electrodes. Polyformamide-derived carbon nanowire arrays are in-situ synthesized as N-containing carbon coatings for cellulose-based carbon fibers. More intriguingly, H2O2 activation further enhances the hierarchical porous structure. Benefiting from the synergistic effect of free-standing feature, high electrolyte compatibility, interconnected conductive fiber networks, well-developed hierarchical porous structure and stable heteroatom-doped carbon coatings, the designed electrodes possess high accessibility of electrolyte ions and effective ion/electron transport channels. Thus, the specific capacitance reaches 275.6F g−1 at 0.5 A g−1 for aqueous supercapacitor. The solid-state symmetric supercapacitor demonstrates the specific capacitance of 126.5F g−1 at 0.5 A g−1 with the capacitance retention of 64.5% even when the current densities increased by 40-folds. Their promising energy density (17.5 Wh kg−1) and power density (12.3 kW kg−1) closing to the state-of-the-art biomass-derived free-standing solid-state symmetric supercapacitors. This breakthrough symbolizes a step forward in the advancement of biomass as high‐performance electrodes for supercapacitors.

NiCo2O4 nanosheet stereostructure with N-doped carbon/Co array supports derived from Co-MOF for asymmetric supercapacitor

• NiCo 2 O 4 nanosheets supported by NC/Co nanowires is used as binder-free electrode. • NiCo 2 O 4 @NC/Co electrode shows high specific capacitance and good cycle stability. • The solid-state ASC is assembled based on NiCo 2 O 4 @NC/Co and NC electrodes. • NiCo 2 O 4 @NC/Co // NC ASC shows a 1.6 V operating potential and 81.1 % retention. The performance of supercapacitors not only depends on the structure of the electrode but also relates to the composition of electrode material. The binder-free integrated electrodes were obtained from NiCo 2 O 4 nanosheets grown on nitrogen-doped carbon and Co aggregation (NC/Co) nanowires through a hydrothermal process and subsequent annealing. The NiCo 2 O 4 @NC/Co composite presents the stereostructure with NC/Co nanowire supports and intertwined NiCo 2 O 4 ultrathin nanosheets. The NiCo 2 O 4 @NC/Co electrode demonstrates excellent electrochemical capacitive performances and cycling stability, where it illustrates a splendid specific capacitance of 1112 F g −1 at 1 A g -1 and maintains around 90.7 % of the maximum capacitance after 5000 cycles. Besides, the functionalized asymmetric supercapacitor (ASC) was fabricated based on NiCo 2 O 4 @NC/Co and NC with KOH-PVA solid electrolyte. The NiCo 2 O 4 @NC/Co // NC ASC possesses a stabilized operating potential range of 1.6 V and retains around 81.1 % retention after 5000 cycles. This makes a great potential for Ni-Co multiple compound electrodes for high-performance energy storage systems.

Batch Nanofabrication of Suspended Single 1D Nanoheaters for Ultralow-Power Metal Oxide Semiconductor-Based Gas Sensors.

The demand for power-efficient micro-and nanodevices is increasing rapidly. In this regard, electrothermal nanowire-based heaters are promising solutions for the ultralow-power devices required in IoT applications. Herein, a method is demonstrated for producing a 1D nanoheater by selectively coating a suspended pyrolyzed carbon nanowire backbone with a thin Au resistive heater layer and utilizing it in a portable gas sensor system. This sophisticated nanostructure is developed without complex nanofabrication and nanoscale alignment processes, owing to the suspended architecture and built-in shadow mask. The suspended carbon nanowires, which are batch-fabricated using carbon-microelectromechanical systems technology, maintain their structural and functional integrity in subsequent nanopatterning processes because of their excellent mechanical robustness. The developed nanoheater is used in gas sensors via user-designable localization of the metal oxide semiconductor nanomaterials onto the central region of the nanoheater at the desired temperature. This allows the sensing site to be uniformly heated, enabling reliable and sensitive gas detection. The 1D nanoheater embedded gas sensor can be heated immediately to 250°C at a remarkably low power of 1.6mW, surpassing the performance of state-of-the-art microheater-based gas sensors. The presented technology offers facile 1D nanoheater production and promising pathways for applications in various electrothermal devices.

Catalytic Growth of Carbon Nanowires on Thin SS-410 Sheet by CVD Method and Its Adsorption Behavior Toward Copper Ions

Catalytic Growth of Carbon Nanowires on Thin SS-410 Sheet by CVD Method and Its Adsorption Behavior Toward Copper Ions

Fabrication of manganese borate/iron carbide encapsulated in nitrogen and boron co-doped carbon nanowires as the accelerated alkaline full water splitting bi-functional electrocatalysts

With high prices of precious metals (such as platinum, iridium, and ruthenium) and transition metals (such as cobalt and nickel), the design of high-efficiency and low-cost non-precious-metal-based catalysts using iron (Fe) and manganese (Mn) metals for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are critical for commercial applications of water splitting devices. In the study, without using any template or surfactant, we successfully designed novel cross-linked manganese borate (Mn3(BO3)2) and iron carbide (Fe3C) embedded into boron (B) and nitrogen (N) co-doped three-dimensional (3D) hierarchically meso/macroporous carbon nanowires (denoted as FexMny@BN-PCFs). Electrochemical test results showed that the HER and OER catalytic activities of Fe1Mn1@BN-PCFs were close to those of 20 wt% Pt/C and RuO2. For full water splitting, (-) Fe1Mn1@BN-PCFs||Fe1Mn1@BN-PCF (+) cell achieved a current density of 10 mA cm−2 at a cell voltage of 1.622 V, which was 14.2 mV larger than that of (-) 20 wt% Pt/C||RuO2 (+) benchmark. The synergistic effect of 3D hierarchically meso/macroporous architectures, excellent charge transport capacity, and abundant active centers (cross-linked Mn3(BO3)2/Fe3C@BNC, BC3, pyridinic-N, MNC, and graphitic-N) enhanced the water splitting catalytic activity of Fe1Mn1@BN-PCFs. The (-) Fe1Mn1@BN-PCFs||Fe1Mn1@BN-PCF (+) cell exhibited excellent stability owing to the superior structural and chemical stabilities of 3D hierarchically porous Fe1Mn1@BN-PCFs.

Synthesis and stockpile of polyynes in paraffin as well as extraction for preparing single-walled carbon nanowires (LLCCs@SWCNTs)

The polyynes are extremely unstable and reactive, and their long-term storage is still a challenge. We first used paraffin as an organic solvent in a submerged electric arc for preparing polyynes, placed them in solid paraffin at room temperature, and assessed their storage stability. One month late, we extracted the polyynes from paraffin, and separated the extracted polyynes by HPLC for obtaining single isolated polyynes. The polyynes extracted from solid paraffin were also purified and filled into open-ended single-walled carbon nanotubes (SWCNTs) to obtain polyynes@SWCNTs samples, which were heated to prepare single-walled carbon nanowires (SWCNWs, LLCCs@SWCNTs), made of long linear carbon chains (LLCCs) inserted inside SWCNTs. The 4L band at 7250 cm−1 was observed in the normal Raman spectra of SWCNWs for the first time. This work solves the problem of long-term storage of polyynes, and opened new avenues for exploring physical properties and applications of polyynes, LLCCs and SWCNWs.

Enhancing the Thermal Conductivity of Amorphous Carbon with Nanowires and Nanotubes.

The thermal conductivity of nanostructures can be obtained using atomistic classical Molecular Dynamics (MD) simulations, particularly for semiconductors where there is no significant contribution from electrons to thermal conduction. In this work, we obtain and analyze the thermal conductivity of amorphous carbon (aC) nanowires (NW) with a 2 nm radius and aC nanotubes (NT) with 0.5, 1 and 1.3 nm internal radii and a 2 nm external radius. The behavior of thermal conductivity with internal radii, temperature and density (related to different levels of hybridization), is compared with experimental results from the literature. Reasonable agreement is found between our modeling results and the experiments for aC films. In addition, in our simulations, the bulk conductivity is lower than the NW conductivity, which in turn is lower than the NT conductivity. NTs thermal conductivity can be tailored as a function of the wall thickness, which surprisingly increases when the wall thickness decreases. While the vibrational density of states (VDOS) is similar for bulk, NW and NT, the elastic modulus is sensitive to the geometrical parameters, which can explain the enhanced thermal conductivity observed for the simulated nanostructures.

Helical Carbon Nanowires for Magnetic-Field-Controlled Swimming

Helical Carbon Nanowires for Magnetic-Field-Controlled Swimming

Schottky-like barrier characterization of field-effect transistors with multiple quasi-ballistic channels

The potential barrier height at the interface formed by a metal contact and multiple one-dimensional (1D) quasi-ballistic channels in field-effect transistors is evaluated across different carbon nanotube and nanowire device technologies by means of a Landauer–Büttiker-based extraction methodology (LBM) adapted for multiple 1D-channels. The extraction methodology yields values for an effective Schottky barrier height and a gate coupling coefficient, an indicator of the device working at the quantum capacitance limit. The novel LBM-based approach embracing the mechanisms in 1D electronics is compared to the conventional activation energy method not considering such effects. The latter approach underestimates the potential barrier height at metal–channel interfaces in comparison to the novel methodology. A test structure based on a displaced gate device is proposed based on numerical device simulation results toward an improved accuracy of the method.

Unraveling the Role of Nitrogen‐Doped Carbon Nanowires Incorporated with MnO2 Nanosheets as High Performance Cathode for Zinc‐Ion Batteries

Manganese‐based cathode materials are considered as a promising candidate for rechargeable aqueous zinc‐ion batteries (ZIBs). Suffering from poor conductive and limited structure tolerance, various carbon matrix, especially N‐doped carbon, were employed to incorporate with MnO2 for greatly promoted electrochemical performances. However, the related underlying mechanism is still unknown, which is unfavorable to guide the design of high performance electrode. Herein, by incorporating layered MnO2 with N‐doped carbon nanowires, a free‐standing cathode with hierarchical core‐shell structure (denoted as MnO2@NC) is prepared. Benefiting from the N‐doped carbon and rational architecture, the MnO2@NC electrode shows an enhanced specific capacity (325 mAh g−1 at 0.1 A g−1) and rate performance (90 mAh g−1 at 2 A g−1), as well as improved cycling stability. Furthermore, the performance improvement mechanism of MnO2 incorporated by N‐doped carbon is investigated by X‐ray photoelectron spectroscopy (XPS), Raman spectrums and density functional theory (DFT) calculation. The N atom elongates the Mn‐O bond and reduces the valence of Mn4+ ion in MnO2 crystal by delocalizing its electron clouds. Thus, the electrostatic repulsion will be weakened when Zn2+/H+ insert into the host MnO2 lattices, which is profitable to more cation insertion and faster ion transfer kinetics for higher capacity and rate capability. This work elucidates a fundamental understanding of the functions of N‐doped carbon in composite materials and shed light on a practical pathway to optimize other electrode materials.

Single-Atom Iron Anchored on 2-D Graphene Carbon to Realize Bridge-Adsorption of O-O as Biomimetic Enzyme for Remarkably Sensitive Electrochemical Detection of H2O2.

Single-atom catalysis is mainly focused on its dispersed high-density catalytic sites, but delicate designs to realize a unique catalysis mechanism in terms of target reactions have been much less investigated. Herein an iron single atomic site catalyst anchored on 2-D N-doping graphene (Fe-SASC/G) was synthesized and further employed as a biomimetic sensor to electrochemically detect hydrogen peroxide, showing an extremely high sensitivity of 3214.28 μA mM-1 cm-2, which is much higher than that (6.5 μA mM-1 cm-2) of its dispersed on 1-D carbon nanowires (Fe-SASC/NW), ranking the best sensitivity among all reported Fe based catalyst at present. The sensor was also used to successfully in situ monitor H2O2 released from A549 living cells. The mechanism was further systematically investigated. Results interestingly indicate that the distance between adjacent single Fe atomic catalytic sites on 2-D graphene of Fe-SASC/G matches statistically well with the outer length of bioxygen of H2O2 to promote a bridge adsorption of -O-O- for simultaneous 2-electron transfer, while the single Fe atoms anchored on distant 1-D nanowires in Fe-SASC/NW only allow an end-adsorption of oxygen atoms for 1-electron transfer. These results demonstrate that Fe-SASC/G holds great promise as an advanced electrode material in selective and sensitive biomimetic sensor and other electrocatalytic applications, while offering scientific insights in deeper single atomic catalysis mechanisms, especially the effects of substrate dimensions on the mechanism.