One-dimensional Carbon Nanofibers Research Articles

CoSe2 nanocrystals embedded in one-dimensional mesoporous carbon nanofibers as advanced anode for potassium-ion storage

High-performance potassium-ion batteries have received great attention for electrochemical energy storage owing to their low redox potential, abundant natural resources and excellent safety. As an advanced negative material, CoSe2 has been widely investigated for potassium-ion batteries. Unfortunately, the pure CoSe2 anode suffers from the fast capacity decay and sluggish kinetics, preventing its practical application. Herein, we introduce a novel strategy to fabricate the CoSe2 nanoparticles embedded in one-dimensional mesoporous carbon nanofibers (denoted as 1D-CoSe2@CNFs) with superior high-rate property and good cycle stability for the first time. In this designed material, the conductive carbon nanofibers are loaded with CoSe2 particles. The obtained 1D-CoSe2@CNFs anode shows a specific capacity of 706.3 mAh/g at 0.1 A/g and presents a high capacity retention ratio of around 96.3 % at 5 A/g over 400 cycles. Therefore, this fabricated 1D-CoSe2@CNFs nanocomposite can be employed as a novel negative electrode for potassium-ion storage.

Thin thickness electromagnetic wave absorbent: Fe3O4 decorated carbon nanofibers composite with designable 3D hierarchical architecture

Designable 3D hierarchical architecture with multi-component heterostructure has been built to form a connected network by fully utilizing the advantages of one-dimensional carbon nanofibers. Fe3O4 decorated carbon nanofibers, which exhibited core-shell microstructures, were successfully prepared by solvothermal and electrospinning technology. Their electromagnetic wave absorption (EWA) performances were explored. The morphology which determined the electromagnetic (EM) parameters can be controlled by adjusting the mass ratio of the raw material. The Fe3O4 decorated carbon nanofibers composite showed an excellent absorbing capability. At a thickness of 2.5 mm, the minimum reflection loss (RLmin) value was −28.28 dB. In particular, the widest effective absorption bandwidth (EAB) can reach up to 2.96 GHz at 1.5 mm. It was more surprising that the effective absorption (RL ≤ −10 dB) occurred when the thickness was only 1.0 mm. The absorption mechanism study revealed that the connected structure facilitated the formation of conductive networks, leading to conductive loss, multiple reflection and scatterings, and interfacial polarization loss. The defects that created during carbonization process enhanced the dipole polarization. The generated magnetic loss which mainly consisted of natural resonance and exchanged resonance loss enhanced the attenuation of EW. Moreover, good impedance matching resulting from the synergistic effect of composition and unique porous network also played an important role. The little filler loading and the thin thickness make the composite have a high EWA performance, which is promising for EWA applications.

Construction of spherical heterogeneous interface on ZnFe2O4@C composite nanofibers for highly efficient microwave absorption

Enriching the electromagnetic wave loss mechanism and improving the impedance matching are the keys to improve the electromagnetic wave absorption performance of carbon fibers. In this study, beaded ZnFe2O4@C absorbing composite fibers (ZFCF) with synergistic effects of magnetic loss and dielectric loss was prepared by electrospinning and heat treatment. ZnFe2O4 magnetic particles effectively improve the impedance matching and increase the loss mechanism of carbon nanofibers. The optimal ZFCF composite has excellent absorption performance, with a minimum reflection loss of −53.6 dB at 2.64 mm and the widest effective absorption bandwidth of 4.32 GHz. The excellent absorption performance is attributed to significant magnetic losses from eddy currents and magnetic resonance generated by ZnFe2O4, and strong interfacial polarization from the numerous heterogeneous interfaces. Additionally, the one-dimensional carbon nanofibers create a conductive network and structural defects that enhance conductive loss and dipole polarization effects. Moreover, the RCS of ZFCF composite was significantly reduced by −32.85 dBm2. The combination of simulation technology and material design is of great significance for the study of electromagnetic wave absorption mechanism and the rational design of electromagnetic wave absorbing coatings.

Dual-catalytic activation of Pt and MoSxOy on carbon nanofibers for NO2 sensors

To achieve highly sensitive chemiresistive gas sensors, facile and effective synthesis for catalytic decoration is essential on an electrically conductive scaffold containing a large surface area and high porosity. Herein, we report a new synthetic strategy for the functionalization of one-dimensional carbon nanofibers (CNFs) using dual-catalytic nanoparticles (NPs) of both oxygen-incorporated MoS2 (MoSxOy) and Pt. The functionalized CNFs were synthesized through an electrospinning process followed by heat treatment in a reducing ambient to ensure the decoration of ultra-small MoSxOy and Pt NPs along the CNFs (Pt-MoSxOy@CNFs). As a result, Pt-MoSxOy@CNFs exhibited an improved sensing response of 39.6% toward 5 ppm of NO2 as compared to the responses of pristine CNFs (7.3%) and MoSxOy@CNFs (13.7%) at room temperature. At the optimized operating temperature of 150 °C, the Pt-MoSxOy@CNFs exhibited a 5.8-fold higher response than that of the pristine CNFs and also presented fully reversible and selective sensing properties. The enhanced NO2 sensing properties were primarily attributed to the chemical sensitization of Pt NPs toward NO2 and a p-n heterojunction between the CNFs and MoSxOy NPs. This study demonstrates the uniform distribution of multiple nano-sized catalysts on CNFs, paving the way for establishing multiplexed sensor arrays and application in electronic nose systems.

(Digital Presentation) Electrospun N-Doped CNFs Embedded Metal Oxides with Improved Graphitization for Superior Pseudocapacitive Energy Storage

One-dimensional carbon nanofibers (CNFs) based pseudocapacitive hybrid electrodes are the next step forward in achieving highly efficient supercapacitor(SCs) electrodes. However, it is still a paramount challenge to develop rationally designed CNFs with sufficient pseudocapacitive surface functionalities, and adequate porosity via a facile synthesis for better practical applicability. Herein, we are reporting a single-step electrospinning methodology followed by carbonization to generate a unique spatial 1D structure with metal oxide (MO) particles embedded in CNFs (M-CNFs). By optimizing the polymer ratio with that of MO, it was possible to obtain an in-situ N-enriched porous CNF network generating a predominant pseudocapacitive charge-storing mechanism. The resulting material is a synergistic combination of MOs, and surface-enriched N-CNFs with good electrical properties and high surface area, suitable to be employed as electrodes for SCs. A deep investigation of the M-CNFs properties has been performed to understand the physical characteristics of the hybrid MO/CNFs material. Further, a flexible symmetric SC device exploiting the polymeric gel-based (PVA+ H2SO4) electrolyte was assembled delivering a maximum energy density of up to 50 Wh Kg-1 and capacitance retention of 90% with a coulombic efficiency of 95%, enabling both electric double-layer and pseudo-capacitance behaviors. The resulting performances of the here-proposed material allow the prediction of the enormous potentialities of these flexible energy-storage devices for industrial-scale application. Keywords: surface N enrichment, electrospinning, hybrid CNFs, flexible symmetric supercapacitors.

Carbonization of Ni@SiC@C nanoparticles reinforced PAN nanofibers for adjustable impedance matching

Achieving a broad bandwidth and efficient absorption of electromagnetic wave absorption materials remains a significant challenge, especially when considering electromagnetic pollution protection. One-dimensional carbon nanofibers with a three-dimensional network structure have been extensively studied to address this need. However, the high permittivity of carbon nanofibers results in a strong impedance mismatch with free space. In this work, we successfully dispersed double-shell Ni@SiC@C nanoparticles into one-dimensional carbon nanofibers (Ni@SiC@C CNFs) using electrospinning and heat treatment. We extensively explored the effect of carbonization temperature on the impedance matching and magnetic-dielectric loss for electromagnetic wave. The presence of rich interfaces from the double-shell nanoparticles and defects from N-doping optimizes the impedance matching of the composites. The exceptional electromagnetic wave absorption properties of the Ni@SiC@C CNFs are attributed to the synergistic effect between the three-dimensional conductive network, the interface electronic engineering induced by the sensibly loaded double-shell nanoparticles, and the multiple reflections, especially at a carbonization temperature of 600 ℃. The achieved minimum reflection loss value has been measured at an outstanding −53.27 dB, coupled with a remarkable absorption bandwidth that spans from 2.53 GHz to 18.00 GHz (15.47 GHz) across various thicknesses. These findings underscore the potential of the meticulously engineered Ni@SiC@C CNFs as highly promising candidates for efficient and broadband electromagnetic wave absorption applications.

A flexible wearable self-supporting hybrid supercapacitor device based on hierarchical nickel cobalt sulfide@C electrode

A flexible wearable electrode consisting of nickel–cobalt sulfide (NCS) nanowires was fabricated in this study. Self-supporting NCS was grown in situ on porous carbon nanofibers without a binder as a novel material for supercapacitor electrodes. The NCS nanowires were grown using cyclic voltammetry electrodeposition, which proved to be a fast and environmentally friendly method with good controllability of the material structure. One-dimensional carbon nanofibers (C) have high surface-area-to-volume ratios, short ion transmission distances, excellent mechanical strengths, and remarkable flexibilities. Moreover, the NCS@C flexible electrode exhibited a synergetic effect with the active compounds, and the dense active sites were uniformly distributed across the entire surface of the carbon fibers, enabling rapid electron transport and enhancing the electrochemical properties of the NCS@C nanowires. The NCS@C achieved specific capacitances of 334.7 and 242.0 mAh g−1 at a current density of 2 A g−1 and high current densities (up to 40 A g−1), respectively, corresponding to a 72.3% retention rate. An NCS@C-nanofilm-based cathode and an activated-carbon-based anode were used to fabricate a flexible asymmetric supercapacitor. The device exhibited high energy and power densities of 12.91 Wh kg−1 and 358 W kg−1, respectively.

Construction of Carbon Nanofiber-Wrapped SnO2 Hollow Nanospheres as Flexible Integrated Anode for Half/Full Li-Ion Batteries.

SnO2 is deemed a potential candidate for high energy density (1494 mAh g-1) anode materials for Li-ion batteries (LIBs). However, its severe volume variation and low intrinsic electrical conductivity result in poor long-term stability and reversibility, limiting the further development of such materials. Therefore, we propose a novel strategy, that is, to prepare SnO2 hollow nanospheres (SnO2-HNPs) by a template method, and then introduce these SnO2-HNPs into one-dimensional (1D) carbon nanofibers (CNFs) uniformly via electrospinning technology. Such a sugar gourd-like construction effectively addresses the limitations of traditional SnO2 during the charging and discharging processes of LIBs. As a result, the optimized product (denoted SnO2-HNP/CNF), a binder-free integrated electrode for half and full LIBs, displays superior electrochemical performance as an anode material, including high reversible capacity (~735.1 mAh g-1 for half LIBs and ~455.3 mAh g-1 at 0.1 A g-1 for full LIBs) and favorable long-term cycling stability. This work confirms that sugar gourd-like SnO2-HNP/CNF flexible integrated electrodes prepared with this novel strategy can effectively improve battery performance, providing infinite possibilities for the design and development of flexible wearable battery equipment.

Seed-assisted in situ ZIF-8 growth on carbon nanofibers for enhanced microwave absorption

The design and preparation of excellent microwave absorbing materials is of great importance facing increasingly negative effects of electromagnetic (EM) wave radiation and interference. Combining metal-organic frameworks (MOFs) with one-dimensional (1D) carbon nanofibers is a valuable approach to improve microwave absorption performance. Herein, C/zinc oxide (ZnO) nanofiber composites were synthesized using the seed-assisted in situ electrospinning method, with the precursor being a zinc-based zeolitic imidazolate framework (ZIF-8). The unique porous structure and the heterointerfaces formed between C and ZnO facilitated the scattering and multiple reflections of microwaves. On account of the combination of interfacial polarization loss, dipole polarization loss and conduction loss, the C/ZnO nanofiber composites exhibited outstanding microwave absorption performance. The minimum reflection loss (RLmin) of −58 dB at 7.5 GHz as well as an effective absorption bandwidth (EAB) of 6.5 GHz was achieved. This work provides an innovative methodology for developing highly efficient microwave absorbing materials using a combination of carbon materials and MOF nanoparticles.

Construction of Hollow Carbon Nanofibers with Graphene Nanorods as Nano-Antennas for Lower-Frequency Microwave Absorption.

Electromagnetic (EM) wave absorbers at a lower-frequency region (2-8 GHz) require higher attenuation ability to achieve efficient absorption. However, the impedance match condition and attenuation ability are usually inversely related. Herein, one-dimensional hollow carbon nanofibers with graphene nanorods are prepared based on coaxial electrospinning technology. The morphology of graphene nanorods can be controlled by the annealing process. As the annealing time increased from 2 to 8 h, graphene nanospheres grew into graphene nanorods, which were catalyzed by Co catalysts derived from ZIF-67 nanoparticles. These nanorods can play the role of nano-antennas, which can guide EM waves into materials to enhance impedance match conditions. As a result, the carbon nanofibers with graphene nanorods possess a larger impedance match area with higher attenuation ability. The minimum reflection loss reaches -57.1 dB at a thickness of 4.6 mm, and the effective absorption bandwidth can cover almost both the S and C bands (2.4-8 GHz). This work contributes a meaningful perspective into the modulation of microwave absorption performance in the lower-frequency range.

Bismuth-Decorated Honeycomb-like Carbon Nanofibers: An Active Electrocatalyst for the Construction of a Sensitive Nitrite Sensor.

The existence of carcinogenic nitrites in food and the natural environment has attracted much attention. Therefore, it is still urgent and necessary to develop nitrite sensors with higher sensitivity and selectivity and expand their applications in daily life to protect human health and environmental safety. Herein, one-dimensional honeycomb-like carbon nanofibers (HCNFs) were synthesized with electrospun technology, and their specific structure enabled controlled growth and highly dispersed bismuth nanoparticles (Bi NPs) on their surface, which endowed the obtained Bi/HCNFs with excellent electrocatalytic activity towards nitrite oxidation. By modifying Bi/HCNFs on the screen-printed electrode, the constructed Bi/HCNFs electrode (Bi/HCNFs-SPE) can be used for nitrite detection in one drop of solution, and exhibits higher sensitivity (1269.9 μA mM-1 cm-2) in a wide range of 0.1~800 μM with a lower detection limit (19 nM). Impressively, the Bi/HCNFs-SPE has been successfully used for nitrite detection in food and environment samples, and the satisfactory properties and recovery indicate its feasibility for further practical applications.

Heterodimensional structure porous nanofibers embedded confining magnetic nanocrystals for electromagnetic functional material and device

The development of electronic devices and communication technology has put forward higher requirements for electromagnetic (EM) materials, and the exploration of multifunctional EM materials has become a new trend. Herein, heterodimensional structured porous nanofibers are constructed by zero-dimensional Fe nanocrystals and one-dimensional carbon nanofibers, which show excellent microwave absorption and electromagnetic interference (EMI) shielding performance. The balance between impedance matching and EM energy attenuation ability can be tailored through the tunable conductive network. The maximum reflection loss (RL) value of −56.8 dB can be achieved at a lower loading ratio, and the efficient EMI shielding effectiveness of 29.3 dB can be obtained at a higher loading ratio. In addition, the green EMI shielding with absorption as the main microwave attenuation mechanism can be observed in the higher frequency range. An EM energy conversion device is designed to effectively recover wasted EM energy. The EM energy is converted into valuable electrical energy through multiple loss mechanisms caused by heterodimensional structures. This work provides new guidance for the realization of multifunctional EM materials and devices.

Pyrochlore LaSrSn2O7 nanoparticles anchored on carbon nanofibers as bifunctional catalysts for an efficient Li-O2 battery

The slow reaction kinetics of oxygen reduction reaction for Li2O2 formation and oxygen evolution reaction for Li2O2 decomposition with poor electrocatalytic activities have been a problem to be solved for the commercialization of lithium-oxygen (Li-O2) batteries. Bifunctional catalysts composed with pyrochlore LaSrSn2O7 nanoparticles (LSSO NPs) and one-dimensional (1D) carbon nanofibers (NFs) were prepared and their catalytic performances were investigated for Li-O2 batteries. As-obtained 1D carbon@LaSrSn2O7 (C@LSSO) NFs composites in Li-O2 battery cathode delivered excellent initial specific capacity (ca. 8067.3 mAh g−1). In addition, decent cycle durability of the C@LSSO cathode was accomplished over 54 cycles with a low overpotential gap of 1.01 V at a rate of 200 mA g−1 with a specific capacity limit of 500 mAh g−1, in comparison to the LSSO NPs and ketjen black carbon. The enhanced properties suggest that these composite structures of pyrochlore LSSO NPs with 1D carbon NFs backbones could be a prospective bifunctional catalyst in the development of the high-performance Li-O2 battery.

Integrated host configuration of flexibly fibrous skeleton towards efficient polysulfide conversion and dendrite-free behavior in stable lithium-sulfur pouch cells

The commercialization of lithium-sulfur (Li-S) batteries is obstructed by the sluggish sulfur electrochemical reaction, severe polysulfide shuttling effect, and damaging dendritic lithium growth. Herein, a three-dimensional (3D) conductive carbon nanofibers skeleton-based bifunctional electrode host material is fabricated, which consists of a two-dimensional (2D) ultra-thin NiSe2-CoSe2 heterostructured nanosheet built on one-dimensional (1D) carbon nanofibers (NiSe2-CoSe2@CNF). When serving as cathodic host, the heterostructured NiSe2-CoSe2@CNF offers a synergistic function of polysulfide confinement and catalysis conversion. The S/NiSe2-CoSe2@CNF cathode shows outstanding cycling stability of 0.03% capacity decay rate per cycle over 500 cycles at 1 C. As anodic host, the NiSe2-CoSe2@CNF with high-flux Li+ diffusion property and good lithiophilic capability realizes dendrite-free Li plating/stripping behavior. Benefiting from these synergistically merits, the Li-S full cell with S/NiSe2-CoSe2@CNF|Li/NiSe2-CoSe2@CNF electrodes exhibits excellent electrochemical performance including a high specific capacity of 1021 mA h g−1 over 100 cycles at 0.2 C and reversible areal capacity of 3.05 mA h cm−2 under a high sulfur loading of 4.33 mg cm−2 at 0.1 C. The pouch cell also delivers ultra-stable Li/S electrochemistry. This study demonstrates a rational and universal electrode construction strategy for developing practical and high-energy Li-S batteries.

Bean pod-like hollow Zn2SnO4/SnO2 heterostructures in N-doped carbon nanofibers as anode material for high performance lithium storage

Tin-based composites have been extensively investigated as a potential anode for high performance lithium-ion batteries (LIBs) up until this point. However, because of extreme volume expansion and crystal crushing, the researchers have consistently experienced a loss in capacity during lithiation and alloying. To buffer the volume change and achieve superior rate capability, the hollow cube-shaped Zn2SnO4/SnO2 which is wrapped with one-dimensional N-doped carbon nanofibers (CNFs) is prepared. The composites display a delicate bean pod-like heterointerface structure, in which the built-in electric field between Zn2SnO4 and SnO2 can help to speed up the transportation of Li-ions during lithiation and delithiation processes. Additionally, the abundant Zn2SnO4/SnO2 heterointerfaces expose more active sites and make it easier for electrolyte and Li-ion to penetrate. And the N-doped carbon skeleton outside of the Zn2SnO4/SnO2 can help to keep the structural integrity and suppress volume expansion during cycling. As expected, the as-prepared samples exhibit excellent rate performance and a very high ultimate discharge capacity of 765.9 mA h g−1 after 500 cycles at current density of 1.0 A g−1. Furthermore, a full-cell with a prelithiated Zn2SnO4/SnO2 @CNFs-600 anode and a LiFePO4 cathode also displays superior rate and cycling performance. This work highlights the significance of chemical heterointerface engineering in the design of high-performance electrodes for LIBs.

Flexible cobalt nanoparticles/carbon nanofibers with macroporous structures toward superior electromagnetic wave absorption

The increasing electromagnetic (EM) pollution that has seriously threatened human health and electronic devices urgently required high-performance absorbents toward attenuating EM wave (EMW). The combination of microstructure modulation and appropriate components regulation has proven to be a feasible strategy for improving the EMW absorption performance of absorbents. In this work, well-designed one-dimensional carbon nanofibers with macroporous structures and uniformly magnetic metal nanoparticles modification were prepared by the hard-template assisted electrospinning method followed by carbonization and template-elimination processes. The strong interfacial polarization loss and multireflection strengthened by the hollow structures and the magnetic loss induced by the introduced cobalt nanoparticles evidently enhanced the impedance matching level of the macroporous carbon nanofibers/cobalt nanoparticles (MCF/Co). As a result, MCF/Co composite offers broad absorption bandwidth (6.24 GHz) and strong electromagnetic wave absorption performance (−40.1 dB) at a thickness of 3.0 mm. This work inspires the rational one-dimensional macroporous carbon nanofibers design for new-generation EMW materials and provides an important research basis for the porous flexible EMW absorption materials.

Integrating built-in fine alloying FeNi3 in carbon nanofiber reinforcing intermetallic synergy for PMS activation to degrade Bisphenol A

Heterogeneous peroxymonosulfate (PMS) activation for the mineralization of pollutants has attracted growing attention, while alloying bimetal catalysts afford big promises in synergetic catalysis. Here, by an alteration of electrospun precursor, one-dimensional carbon nanofiber (CNF) integrated with Prussian blue analogs (PBA)-derived alloyed fine plasmonic FeNi3 hybrid catalyst (FeNi3@CNF) was constructed by electrospinning technique with subsequent confinement calcination. The amount of PBA in fiber precursor and thermal treatment temperature were alternatively adjusted to control the distribution and concentration of alloyed FeNi3 in carbon nanofiber. This unique structure combines the advantages of abundant internal porosity of N-doping carbon fiber and uniforms active FeNi3 alloys with highly-exposed reactive sites, facilitating the electron transport and proximity of reactant molecules in catalytic oxidation. The synergistic and interfacial effect of optimal FeNi3@CNF endowed the ultra-fast degradation activity against bisphenol A (BPA) through rapid persulphate activation to generate four reactive active species. Specifically, 20 mg L−1 of BPA was completely degraded within 4 min with a reaction rate constant of 2.736 min−1. Impressively, by innovating the utilization of the Prussian blue precursor in electrospinning, the optimal FeNi3@CNF shows 18.5, 101.3, and 248.5 times activity enhancement in BPA degradation compared to that of Fe@CNF, Ni@CNF, and Fe&Ni@CNF, revealing the appreciable synergy of bimetallic alloys in PMS activation. In addition, the improved catalytic performance of FeNi3@CNF under light irradiation was also simulated, confirming that the enhanced photothermal conversion ability of plasmonic alloys and carbon fiber advance the degradation of BPA.

Constructing FeS2/TiO2 p-n heterostructure encapsulated in one-dimensional carbon nanofibers for achieving highly stable sodium-ion battery

Iron sulfides (FeS2) is a promising anode material for advanced sodium-ion batteries (SIBs) owing to its high theoretical capacity of 894.0 mAh/g and abundant natural resource. However, the inferior electronic conductivity, huge volume expansion, and dissolution of sodium polysulfides generated upon conversion reaction process limit its practical application in SIBs. Although the introduction of carbon materials could significantly compensate for conductivity and structural destroy, but the poor cycling stability aroused by active sulfide loss still urgently settled. Herein, TiO2 featuring strong affinity for sodium polysulfides was engaged as one active component to construct FeS2/TiO2 heterostructure. Additionally, TiO2 is a typical n-type semiconductor with a broad bandgap, which will induce the formation of a strong built-in electric field at the interface of FeS2/TiO2 and thus expedite the charge transport during sodium storage process. Consequently, FeS2/TiO2 p-n heterostructure nanoparticles encapsulated in one dimensional carbon nanofibers (FeS2/TiO2@CNFs) were synthesized by simple electrospinning technology and subsequent carbonization/sulfidation treatment, as well as systemically investigated its electrochemical performance as an anode material for SIBs. As expected, FeS2/TiO2@CNFs anode delivers a high specific capacity of 563.1 mAh g-1 at 1.0 A g-1 over 100 cycles, and superior rate capability (404.0 mAh g-1 at 10.0 A g-1). Even after 8000 cycles at 10.0 A g-1, FeS2/TiO2@CNFs anode still exhibits superior cycling durability. Inspired by the admirable sodium storage performance of FeS2/TiO2@CNFs heterostructure, the architectural design strategy is expected to be widely adopted for meliorating the electrochemical performance of metal sulfide anodes.

Graphitic carbon-encapsulated cobalt nanoparticles embedded 1D porous hollow carbon nanofibers as advanced multifunctional electrocatalysts for overall water splitting and Zn-air batteries

Physical mixing of monofunctional noble metal catalysts, such as Pt/C or Ru/IrO2, increases the commercial cost and stability risk of electrodes. Therefore, it is desirable to develop a multifunctional electrocatalyst for zinc-air batteries and integrated electrolytic devices. To develop an effective way to fabricate high-performance multifunctional electrocatalysts by modifying advanced nanostructures, a coaxial electrospinning approach with in-situ synthesis and subsequent carbonization was used to construct a highly integrated three-function catalyst composed of graphitic carbon-encapsulated cobalt nanoparticles embedded into one-dimensional (1D) porous hollow carbon nanofibers (CoNC-HCNFs). Under the synergistic effect of the active material and the advanced nanostructure, the as-prepared CoNC-HCNFs demonstrated an operating overpotential of 186 mV (10 mA cm−2) for the hydrogen evolution reaction (HER), a half-wave potential of 0.83 V (vs. RHE at 10 mA cm−2) for the oxygen reduction reaction (ORR), and a potential of 1.58 V (10 mA cm−2) for the oxygen evolution reaction (OER). With their exceptional multifunctional activities, two CoNC–HCNF-based aqueous zinc-air batteries (ZABs) in series could drive an alkaline water electrolyzer for splitting water. Furthermore, due to the superior mechanical flexibility and rechargeability of the solid-state ZAB, it has great application prospects in powering portable and wearable electronics. This research is expected to offer inspiration for the development of other excellent MOF-based hollow carbon nanofibers and to enable them to be adopted more widely in electrochemical energy conversion and energy storage.

Recyclable Joule heated low shrinkage carbon nanofiber aerogels for microscale oil/water separation

• A freeze-shaping method for fabricating CNFA was proposed. • A novel CNFA was designed by directly using 1D CNF with a vine-wrapped tree structure. • Hydrophobic-lipophilic CNFA with lightweight, high porosity, great elasticity, and high Joule-heating efficiency was obtained. • The cyclic stability of CNFA was proved to be high efficiency Joule-heated adsorption for microscale levels acetone (87%) and DMF (92%). Aerogels have shown great potential as oil adsorbents but their application to the removal of microscale oil from water and their recycling remains problematic. The present work proposed a freeze-shaping method for fabricating carbon nanofiber aerogels (CNFAs) based on the direct use of one-dimensional (1D) carbon nanofibers (CNF) rather than carbonization of polymer aerogels. This technique greatly reduces volume shrinkage and increases the three-dimensional (3D) structural stability of the material. Carbon nanotubes (CNT) and gelatinized starch were incorporated in these aerogels as a conductive enhancement agent and binder, respectively, forming a “vine (CNT)-wrapped tree (CNF)” structure that improved mechanical and Joule-heating performance. The effects of glutaraldehyde added to aerogels as a cross-linking agent on mechanical properties and microstructure were also systematically investigated. The optimized CNFAs combined with low density, high porosity, good elasticity, and superior Joule-heating efficiency along with suitable adsorption capacity, excellent selectivity, and cycling stability. This material was able to selectively remove 87% and 92% of microscale acetone and dimethylformamide (DMF), respectively, from the water after nine cycles of adsorption and Joule-heating. The present work demonstrates a novel means of designing and fabricating a low shrinkage CNFA with outstanding Joule-heating performance having potential practical applications in the remediation of organic pollution.