Hierarchical Carbon Nanofibers Research Articles

Multidimensional and hierarchical design of biomass-derived carbon nanofiber networks for efficient microwave absorption

Carbon materials have gained significant attention for their potential as highly efficient microwave absorbers. However, it remains a challenge to attain a perfect integration of thin thickness, wide frequency bandwidth, lightweight and strong absorption through structural design of carbon materials. Herein, we design multidimensional and hierarchical carbon nanofiber networks consisting of core-shell carbon nanofibers wrapped by hollow carbon nanoparticles, named CPDA@RCNFs. CPDA@RCNFs which are derived from cellulose and polydopamine (PDA) were prepared by electrostatic spinning, deacetylation, self-polymerization, and carbonization, successively. Thanks to the cooperation of three-dimensional conductive networks, core-shell/hollow/porous structures, as well as doped nitrogen and oxygen heteroatoms, CPDA@RCNFs exhibit excellent comprehensive microwave absorption performance. Specifically, an ultra-strong reflection loss value of −63.31 dB and a wide frequency bandwidth of 5.60 GHz (12.32–17.92 GHz) are achieved at a very thin thickness of 1.8 mm with an ultra-low filler loading of 5 wt%. This work provides a new insight into the structural design of advanced high-performance microwave absorption carbon materials.

Self-Supporting Silicon-Based Hierarchical Carbon Nanofibers As Anodes for Lithium-Ion Batteries

Self-Supporting Silicon-Based Hierarchical Carbon Nanofibers As Anodes for Lithium-Ion Batteries

Use of Hierarchical Carbon Nanofibers Decorated with NiCo Nanoparticles for Highly Sensitive Vortioxetine Determination.

A new voltammetry method for the highly sensitive antidepressant drug vortioxetine (VOR) is presented using glassy carbon electrodes modified with hierarchical carbon nanofibers with NiCo nanoparticles (eCNF/CNT/NiCo-GCE). The electrochemical behavior of VOR was investigated by cyclic voltammetry, which indicates that its oxidation is an adsorption-controlled process with the exchange of two electrons and one proton. The effects of various factors on the VOR peak, such as supporting electrolyte type, preconcentration time, and potential, or influence of interferents, were tested using the square wave voltammetry technique (SWV). The linear voltametric response for the analyte was obtained in the concentration range from 0.01·10-6 to 3.0·10-6 mol L-1 with the detection limit of 1.55·10-9 mol L-1 for a preconcentration time of 60 s. The proposed method was successfully applied for highly sensitive VOR determination in complex matrices such as tablets, urine, and plasma with good recovery parameter.

New Electrochemical Sensor Based on Hierarchical Carbon Nanofibers with NiCo Nanoparticles and Its Application for Cetirizine Hydrochloride Determination.

A new electrochemical sensor based on hierarchical carbon nanofibers with Ni and Co nanoparticles (eCNF/CNT/NiCo-GCE) was developed. The presented sensor may be characterized by high sensitivity, good electrical conductivity, and electrocatalytic properties. Reproducibility of its preparation expressed as %RSD (relative standard deviation) was equal to 9.7% (n = 5). The repeatability of the signal register on eCNF/CNT/NiCo-GCE was equal to 3.4% (n = 9). The developed sensor was applied in the determination of the antihistamine drug—cetirizine hydrochloride (CTZ). Measurement conditions, such as DPV (differential pulse voltammetry) parameters, supporting electrolyte composition and concentration were optimized. CTZ exhibits a linear response in three concentration ranges: 0.05–6 µM (r = 0.988); 7–32 (r = 0.992); and 42–112 (r = 0.999). Based on the calibration performed, the limit of detection (LOD) and limit of quantification (LOQ) were calculated and were equal to 14 nM and 42 nM, respectively. The applicability of the optimized method for the determination of CTZ was proven by analysis of its concentration in real samples, such as pharmaceutical products and body fluids (urine and plasma). The results were satisfactory and the calculated recoveries (97–115%) suggest that the method may be considered accurate. The obtained results proved that the developed sensor and optimized method may be used in routine laboratory practice.

Fabricating advanced asymmetric supercapacitors by flame growing carbon nanofibers on surface engineered stainless steel electrode and modulating the redox active electrolyte

A straightforward approach for preparing a hierarchical carbon nanofiber (CNF) electrode through surface-engineering of a stainless steel microwire mesh (SS) current collector is developed. Surface-engineering is achieved via controlled chemical etching SS and subsequent flame depsotion of a CNF coating. In contrast to pristine SS, the surface-engineered SS do not only comprise a unique surface texture but also a higher catalytic activity facilitating the direct growth of CNFs in an ethanol flame. Therefore, the as-fabricated electrode exhibits a high specific capacitance of 2988 F/g at 25 mA/cm 2 in a redox active electrolyte containing Fe 2+/3+ optimized for this electrode/electrolyte system. To maximize their capacitive performance, supercapacitors in a newly designed dual-asymmetric electrode/electrolyte (DASCs) configuration are assembled. Both the CNF positive electrode and the alpha‑molybdenum oxide (MoO 3 ) nanobelt negative electrode are capable to operate in their most suitable electrolyte. Consequently, the DASCs deliver an ultrahigh energy density of 96 Wh/kg at 114 W/Kg and a remarkable capacitance retention. Our results demonstrate the effectiveness of this surface engineering approach for fabricating electrodes, the redox activity modulation of the electrolyte, and the newly designed configuration of the capacitors, on enhancing their performance. • A facile 2-step method for flame catalytic deposition of CNFs on stainless steel mesh was developed. • Surface-engineering provided the resurfaced catalytically active sites for CNF deposition. • Surface-engineering of the mesh provided CNF electrodes with enhanced charge transfer ability. • Supercapacitors with new configuration of dual-asymmetric electrode/electrolyte were assembled. • The flexible solid state device exhibited remarkable energy density of 96 Wh/kg at 114 W/kg.

A Multiscale Strategy to Construct Cobalt Nanoparticles Confined within Hierarchical Carbon Nanofibers for Efficient CO2 Electroreduction.

The efficiency of CO2 electroreduction has been largely limited by the activity of the catalysts as well as the three-phase interface. Herein, a multiscale strategy is proposed to synthesize hierarchical nanofibers covered by carbon nanotubes and embedded with cobalt nanoparticles (Co/CNT/HCNF). The confinement effect of carbon nanotubes can restrict the diameter of the cobalt particles down to several nanometers and prevent the easy corrosion of these nanoparticles. The three-dimensional carbon nanofibers, in size range of several hundred nanometers, improve the electrochemically active surface area, facilitate electron transfer, and accelerate CO2 transportation. These cross-linked carbon nanofibers eventually form a freestanding Co/CNT/HCNF membrane of dozens of square centimeters. Consequently, Co/CNT/HCNF produces CO with 97% faradaic efficiency at only -0.4 VRHE cathode potential in an H-type cell. From the regulation of catalyst nanostructure to the design of macrography devices, Co/CNT/HCNF membrane can be directly used as the gas-diffusion compartment in a flow cell device. Co/CNT/HCNF membrane generates CO with faradaic efficiencies higher than 90% and partial current densities greater than 300mA cm-2 for at least 100-h stability. This strategy provides a successful example of efficient catalysts for CO2 electroreduction and also has the feasibility in other self-standing energy conversion devices.

β‐Phase‐Rich Laser‐Induced Hierarchically Interactive MXene Reinforced Carbon Nanofibers for Multifunctional Breathable Bioelectronics

AbstractHierarchically interactive 3D‐porous soft carbon nanofibers (CNFs) have great potential for wearable bioelectronic interfaces, yet 90% of CNFs are derived from expensive polyacrylonitrile associated with complex production methods. Here, another cost‐effective fluoropolymer, poly(1,1‐difluoroethylene) (PDFE), is introduced to investigate its transition chemistry and structural evolution over laser‐induced carbonization (LIC). The impregnation of Ti3C2Tx‐MXene followed by dehydrofluorination is believed to be crucial to enhance the β‐phase and reinforce PDFE‐based nanofibers. It is explored that the β‐phase of the dehydrofluorinated MXene‐PDFE nanofibers is converted into an sp2‐hybridized hexagonal graphitic structure by cyclization/cross‐linking decomposition during LIC. Remarkably, this approach generates laser‐induced hierarchical CNFs (LIHCNFs) with a high carbon yield (54.77%), conductivity (sheet resistance = 4 Ω sq−1), and stability over 500 bending/releasing cycles (at 10% bending range). Using LIHCNFs, a skin‐compatible breathable and reusable electronic‐tattoo is engineered for monitoring long‐term biopotentials and human–machine interfaces for operating home electronics. The LIHCNFs‐tattoo with high breathability (≈14 mg cm−2 h−1) forms compliant contact with human skin, resulting in low electrode‐skin impedance (23.59 kΩ cm2) and low‐noise biopotential signals (signal‐to‐noise ratio, SNR = 41 dB). This finding offers a complementary polymer precursor and carbonization method to produce CNFs with proper structural features and designs for multifunctional biointerfaces.

Electrospun carbon nanofibers embedded with MOF-derived N-doped porous carbon and ZnO quantum dots for asymmetric flexible supercapacitors

Hierarchical carbon nanofibers are embedded with MOF-derived N-doped porous carbon nanoparticles and decorated with ZnO quantum dots via a co-spinning method.

Hierarchically porous N‐doped carbon nanofibers derived from ZIF‐8/PAN composites for benzene adsorption

AbstractCoupling with electrospinning technique, metal–organic‐frameworks (MOFs)‐derived porous carbon fibers exhibit a great potential application in the adsorption of volatile organic compounds (VOCs) because of their huge surface area, high porosity, as well as sufficient heteroatom‐doped active sites. In this work, the hierarchically porous N‐doped carbon nanofibers are obtained after the pyrolysis of zeolite imidazole framework‐8 and polyacrylonitrile (ZIF‐8/PAN) composite fibers synthesized by electrospinning method. The N‐doped carbon nanofibers fabricated in N2 atmosphere (N‐CF‐N2) present an enhanced adsorption capacity of 694 mg/g for benzene because of the synergistic effect of the hierarchically porous structure and the abundant N‐species‐containing active sites. It is also interesting that the N‐doped hierarchical carbon nanofibers fabricated in Ar atmosphere (N‐CF‐Ar) exhibit a low benzene adsorption as compared with the N‐CF‐N2, which can be attributed to the porous structure damage caused by the bombardment of heavy Ar atoms on the pore shells during the pyrolysis. These results not only show a promising application of the as‐fabricated N‐CF‐N2 in adsorption of VOCs for air purification due to its merit of cost‐efficient, large‐scale production, and excellent adsorption capacity, but also expand the potential of electrospinning technology and composite fibers in volatile organic gas adsorption.

Free-standing hierarchical Co@CoO/CNFs/Cu-foam composite based on electrochemical deposition as high-performance supercapacitor electrode

Three-dimensional structural materials with sufficient reactive contact surface to the electrolyte can significantly improve the capacitance performance of supercapacitors. Herein, we report a facile method to fabricate a hierarchical carbon nanofibers (CNFs) modified Cu-foam supported Co@CoO hybrid as a free-standing and binder-free electrode for supercapacitor application. The optimized Co@CoO/CNFs/Cu-foam shows a high specific capacitance of 19.2 F cm−3 at the current density of 50 mA cm−3 and a remarkable capacitance retention of 97.5% after 5000 cycles in a 3-electrode system. A button-type asymmetric supercapacitor was additionally constructed by using Co@CoO/CNFs/Cu foam as the positive electrode and activated carbon electrode as negative electrode to examine its practical application. The stored energy density reached to 180.5 mWh cm−2 with the corresponding power density of 6000 mW cm−2 at a discharging current density of 4 mA cm−2. An excellent cycling life of retention 100% was maintained after 5000 cycles. The high-surface area and conductivity of the CNFs played a positive role as support to highly-dispersed Co@CoO nanoparticles. The pulsed electrodeposition additionally favored the controllable fabrication of Co@CoO nanoparticles with homogeneously distribution and uniform sizes. The hierarchical hybrid electrode with porous architecture eventually allowed good access of electrolyte and efficient charge storage and transfer, which concomitantly improved its overall electrochemical performance.

Ru nanoparticles encapsulated in ZIFs-derived porous N-doped hierarchical carbon nanofibers for enhanced hydrogen evolution reaction

Ru nanoparticles, encapsulated in ZIFs-derived porous N-doped hierarchical carbon nanofibers with excellent HER performance, were achieved.

Elastic and hierarchical carbon nanofiber aerogels and their hybrids with carbon nanotubes and cobalt oxide nanoparticles for high-performance asymmetric supercapacitors

Although lightweight and elastic carbon nanofiber (CNF)-based aerogels are promising in wearable supercapacitors, it is still a serious issue to produce CNF-based aerogels with satisfactory integrated properties of mechanical strength, compression resilience, conductivity, and electrochemical performances. Herein, elastic aerogel anode materials with welded CNFs are fabricated by electrospining polyacrylonitrile nanofibers with polyvinylpyrrolidone as a solder to weld adjacent nanofibers followed by freeze-drying, carbonization, and CO2 activation, exhibiting remarkable electrical conductivity, excellent reversible compressibility, and a high specific capacitance of 300 F g−1 at 0.3 A g−1. Furthermore, carbon nanotubes (CNTs) are uniformly grown on the CNF surface of the aerogels with the catalysis of metallic Co, while the Co nanoparticles at the CNT tips are oxidized in situ to Co3O4 nanoparticles. The CNF-CNT-Co3O4 hybrid aerogel as a hierarchical cathode exhibits a high specific capacitance of 2376 F g−1 at 1 A g−1. An assembled asymmetric supercapacitor with the activated CNF aerogel as its anode and the hybrid aerogel as its cathode exhibits a considerably high energy density of 48.1 W h kg−1 at 780.2 W kg−1. This study provides a new strategy for constructing lightweight and elastic electrode materials for highly efficient energy-storage application.

Co3O4 Supraparticle-Based Bubble Nanofiber and Bubble Nanosheet with Remarkable Electrochemical Performance.

Hollow nanostructures based on transition metal oxides (TMOs) with high surface‐to‐volumetric ratio, low density, and high loading capacity have received great attention for energy‐related applications. However, the controllable fabrication of hybrid TMO‐based hollow nanostructures in a simple and scalable manner remains challenging. Herein, a simple and scalable strategy is used to prepare hierarchical carbon nanofiber (CNF)‐based bubble‐nanofiber‐structured and reduced graphene oxide (RGO)‐based bubble‐nanosheet‐structured Co3O4 hollow supraparticle (HSP) composites (denoted as CNF/HSP‐Co3O4 and RGO/HSP‐Co3O4, respectively) by solution self‐assembly of ultrasmall Co3O4 nanoparticles (NPs) assisting with polydopamine (PDA) modification. It is proved that the electrochemical performance of Co3O4 NPs can be greatly enhanced by the rationally designed nanostructure of bubble‐like supraparticles combined with carbon materials as excellent electrodes for supercapacitors. The favorable structure and composition endow the hybrid electrode with high specific capacitance (1435 F g−1/1360 F g−1 at 1 A g−1/5 mV s−1) as well as fantastic rate capability. The asymmetric supercapacitors achieve an excellent maximum energy density of 51 W h kg−1 and superb electrochemical stability (92.3% retention after 10 000 cycles). This work suggests that the rational design of electrode materials with bubble‐like superstructures provides an opportunity for achieving high‐performance electrode materials for advanced energy storage devices.

Tannic Acid-Assisted Fabrication of N/B-Codoped Hierarchical Carbon Nanofibers from Electrospun Zeolitic Imidazolate Frameworks as Free-Standing Electrodes for High-Performance Supercapacitors

An effective synthetic route has been reported to prepare N/B co-doped hierarchical carbon nanofibers (NB-HCNFs) as free-standing electrodes for high-performance supercapacitors. Zeolitic imidazolate framework (ZIF-8) nanoparticles were embedded into polyacrylonitrile (PAN) through electrospinning to obtain PAN/ZIF-8 nanofibers. Tannic acid (TA) acted as a coating layer for PAN/ZIF-8 to generate hollow ZIF-8 core structures within the fiber and an intermediate to coordinate with 1,4-benzenediboronicacid (BDBA). After carbonization, the obtained flexible N/B co-doped hierarchical porous carbon nanofibers were used as free-standing electrodes for supercapacitors. Thus, unique nanostructure and the existence of heteroatoms could offer remarkably improved electrochemical properties with a high specific capacitance (288.2 F g−1 at a current density of 1 A g−1) and good cycling stability (96.9% capacitance retention over 8000 cycles at 10 A g−1). In addition, the NB-HCNFs films were assembled into symmetric supercapacitors, which displayed a high energy density and excellent stability (99.7% capacitance retention after 8000 cycles at 10 A g−1). The synthetic method might provide an effective and facile strategy to prepare a variety of hierarchical doped carbon nanomaterials for energy storage.

Hierarchical CNFs/MnCo2O4.5 nanofibers as a highly active oxidase mimetic and its application in biosensing

Recently, much attention has been paid on the nanomaterial-based artificial enzymes due to their tunable catalytic activity, high stability and low cost compared to the natural enzymes. Different from the peroxidase mimics which have been studied for several decades, nanomaterials with oxidase-like property are burgeoning in the recent years. In this paper, hierarchical carbon nanofibers (CNFs)/MnCo2O4.5 nanofibers as efficient oxidase mimics are reported. The products are synthesized by an electrospinning technique and an electrochemcial deposition process in which the CNFs are used as the working electrode where MnCo2O4.5 nanosheets deposit on. The resulting binary metal oxide-based nanocomposites exhibit a good oxidase-like activity toward the oxidations of 3,3′,5,5′tetramethylbenzi-dine (TMB), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium (ABTS) salt and o-phenylenediamine (OPD) without exogenous addition of H2O2. The system of CNFs/MnCo2O4.5-TMB can be used as a candidate to detect sulfite and ascorbic acid via a colorimetric method with a high sensitivity. This work provides the efficient utilization and potential applications of binary metal oxide-based nanocomposites with oxidase activities in biosensors and other biotechnologies.

Electrospun metal-organic framework derived hierarchical carbon nanofibers with high performance for supercapacitors.

A novel N-doped MOF-based hierarchical carbon fiber (NPCF) towards supercapacitors was prepared by the pyrolysis of MOF nanofibers. Due to its unique 1D hollow structures, the NPCF exhibits better energy storage capacity than the other previously reported MOF-derived carbon materials.

Electrospun porous hierarchical carbon nanofibers with tailored structures for supercapacitors and capacitive deionization

Electrospun carbon nanofibers exhibit enhanced capacitive deionization performance in vertical flow-through capacitive deionization for desalination.

Egg-Box Structure in Cobalt Alginate: A New Approach to Multifunctional Hierarchical Mesoporous N-Doped Carbon Nanofibers for Efficient Catalysis and Energy Storage.

Carbon nanomaterials with both doped heteroatom and porous structure represent a new class of carbon nanostructures for boosting electrochemical application, particularly sustainable electrochemical energy conversion and storage applications. We herein demonstrate a unique large-scale sustainable biomass conversion strategy for the synthesis of earth-abundant multifunctional carbon nanomaterials with well-defined doped heteroatom level and multimodal pores through pyrolyzing electrospinning renewable natural alginate. The key part for our chemical synthesis is that we found that the egg-box structure in cobalt alginate nanofiber can offer new opportunity to create large mesopores (∼10–40 nm) on the surface of nitrogen-doped carbon nanofibers. The as-prepared hierarchical carbon nanofibers with three-dimensional pathway for electron and ion transport are conceptually new as high-performance multifunctional electrochemical materials for boosting the performance of oxygen reduction reaction (ORR), lithium ion batteries (LIBs), and supercapacitors (SCs). In particular, they show amazingly the same ORR activity as commercial Pt/C catalyst and much better long-term stability and methanol tolerance for ORR than Pt/C via a four-electron pathway in alkaline electrolyte. They also exhibit a large reversible capacity of 625 mAh g–1 at 1 A g–1, good rate capability, and excellent cycling performance for LIBs, making them among the best in all the reported carbon nanomaterials. They also represent highly efficient carbon nanomaterials for SCs with excellent capacitive behavior of 197 F g–1 at 1 A g–1 and superior stability. The present work highlights the importance of biomass-derived multifunctional mesoporous carbon nanomaterials in enhancing electrochemical catalysis and energy storage.

Ferromagnetic hierarchical carbon nanofiber bundles derived from natural collagen fibers: truly lightweight and high-performance microwave absorption materials

High-performance microwave absorption materials with a broad bandwidth and strong intensity have significant applications in both civil and military areas.

Electrospun carbon nanofibers with surface-attached platinum nanoparticles as cost-effective and efficient counter electrode for dye-sensitized solar cells

Dye-sensitized solar cells (DSCs) have attracted incredible attention in recent years as relatively inexpensive alternative to silicon solar cells. Conventionally, a transparent fluoride-doped tin oxide (FTO) conductive glass with a thin layer coating of platinum (Pt) is used as counter electrode in DSCs. The widespread use of Pt as counter electrode in DSCs is due to its catalytic capability for I3- reduction in electrolyte. However, Pt is costly and can be affected by the corrosive nature of I-/I3- redox couple, which makes it a less desirable candidate for use in industrial scale manufacturing. In this study, carbon nanofibers with surface-attached Pt nanoparticles were prepared by stabilization and carbonization of electrospun polyacrylonitrile (PAN) nanofibers and subsequent controllable Pt nanoparticle growth on the obtained carbon nanofiber surface through redox reaction. The hierarchical carbon nanofibers with surface-attached Pt nanoparticles (ECNFs-PtNPs) were then employed as cost-effective counter electrode in DSCs. The effects of size, morphology, and loading of Pt nanoparticles on performance of DSCs were investigated. Compared to conventional counter electrode, the counter electrode that was made of ECNFs-PtNPs exhibited larger open circuit voltage (Voc). The DSCs that were made with ECNFs-PtNPs counter electrode demonstrated excellent solar energy conversion efficiencies in the range of 7% to 8%.