Hollow Carbon Nanofibers Research Articles

Carbon sustained SnO2-Bi2O3 hollow nanofibers as Janus catalyst for high-efficiency CO2 electroreduction

Electrochemical reduction of CO2 (CRR) into valuable products like formate is an appealing way to alleviate the pressure of the excessive CO2 emission and achieve carbon neutrality. However, exploitation of electrocatalysts with commercial application potentials remains challenging. Herein, we fabricate a hierarchical Janus electrocatalyst with SnO2 and Bi2O3 assembled outside and inside the hollow carbon nanofiber skeleton, respectively. Due to the nanostructuring effect, the catalytic performance of Janus active sites was magnified, achieving a remarkable current density of −220 mA cm−2 for formate production and 91% faradic efficiency at −1.29 V vs. RHE in a flow cell. Besides, the selectivity for formate was maintained over 48 h operation with an outstanding half-cell energy efficiency of 51%. In-situ FT-IR further prove the Janus active sites are conducive to the HCOO* reaction pathway rather than the *COOH way. This study may pave another avenue to prepare nanostructured Janus electrocatalysts for highly efficient CO2 reduction.

Encapsulating Cobalt Nanoparticles in Interconnected N-Doped Hollow Carbon Nanofibers with Enriched CoNC Moiety for Enhanced Oxygen Electrocatalysis in Zn-Air Batteries.

Rational design of bifunctional efficient electrocatalysts for both oxygen reduction (ORR) and oxygen evolution reactions (OER) is desirable—while highly challenging—for development of rechargeable metal–air batteries. Herein, an efficient bifunctional electrocatalyst is designed and fabricated by encapsulating Co nanoparticles in interconnected N‐doped hollow porous carbon nanofibers (designated as Co@N‐C/PCNF) using an ultrafast high‐temperature shock technology. Benefiting from the synergistic effect and intrinsic activity of the Co—N—C moiety, as well as porous structure of carbon nanofibers, the Co@N‐C/PCNF composite shows high bifunctional electrocatalytic activities for both OER (289 mV at 10 mA cm−2) and ORR (half‐wave potential of 0.85 V). The Co—N—C moiety in the composite can modulate the local environmental and electrical structure of the catalysts, thus optimizing the adsorption/desorption kinetics and decreasing the reaction barriers for promoting the reversible oxygen electrocatalysis. Co@N‐C/PCNF‐based aqueous Zn–air batteries (AZAB) provide high power density of 292 mW cm−2, and the assembled flexible ZAB can power wearable devices.

Advanced lithium–sulfur batteries enabled by a SnS2-Hollow carbon nanofibers Flexible Electrocatalytic Membrane

As emerging energy storage systems, lithium-sulfur (Li–S) batteries have engaged extensive attention owing to the ideal energy density. The bottleneck of achieving the practical application on Li–S batteries is the shuttle effects of lithium polysulfide (LiPS) and the sluggish electrochemical conversion kinetics. Here, a flexible SnS2-hollow carbon nanofibers (SnS2@HCNF) membrane is designed as an interlayer to catalyze the conversion of LiPS. Hollow carbon nanofibers (HCNF) provide an electron passageway to accelerate the redox reaction of LiPS, while SnS2 achieves rapid Li ions transport and an efficient catalytic route, promoting the decomposition of Li2S. Owing to the synergistic effect of HCNF and SnS2, the SnS2@HCNF endow the Li–S batteries with high rate performance (694 mAh g−1 at 3C) and low capacity fading rate (0.056 % per cycle during 500 cycles at 1C). The material and design strategy manifested in this work can pave a new way towards developing shuttle suppression interlayers.

Free-standing hollow carbon nanofibers scaffold with spherical nanocavities and lithiophilic N/ZnO heteroatoms as stable dendrite-free lithium metal anode

Metallic Li as substitutional anode materials for high specific capacity lithium-ion batteries (LIBs) has been attached great importance. However, two major problems including serve Li dendrites growth and large volume change need to be settled before it can be commercialized. Herein, a 3D porous hollow carbon nanofibers (MC@HCNFs) with high electron transport rate and low regional current density polarization are designed, which are comprised of MOF-derived N/ZnO co-doped carbon frameworks and embedded carbon nanotubes. The spherical cavities within MC@HCNFs formed by the high-temperature decomposition of MOFs nanoparticles can provide abundant active space for Li metal nucleation and deposition to alleviate the infinite volume expansion, and more importantly regulate homogenous Li ions flow and preferential Li metal deposition to suppress the Li dendrites growth due to the presence of lithiophilic N/ZnO heteroatoms on the surface. As a Li metal carrier, MC@HCNFs displays stable Li platting/stripping for ultralong life spans of 2000 h with lower overpotentials at 1.0 mA cm−2 respectively, which also demonstrate excellent cycle and rate performances when used in LiFePO4-based full cells.

Templated fabrication of perfectly aligned metal-organic framework-supported iron-doped copper-cobalt selenide nanostructure on hollow carbon nanofibers for an efficient trifunctional electrode material

Considering the importance of sustainable energy conversion technologies, the robust development of high-performance tribunitial catalysts for the oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and oxygen reduction reaction (ORR) is of great significance. Herein, a multistep methodology to follow the synthesis of templated supported metal-organic frameworks (MOFs) based on iron-doped copper-cobalt selenide on hollow carbon nanofiber mats (Fe-doped MOF CuCoSe@HCNFs) is utilized as a trifunctional electrocatalyst. As a synthesis of nanoporous electrocatalysts, oxyhydroxide metals are commonly used as a sacrificial template for the development of a porous carbon network. The as-synthesized materials are completely characterized, showing that the templated MOFs exhibit a significant impact on the porous carbon network, surface area, surface defects, and interfacial charge transfer. The superior trifunctional electrocatalyst of the Fe-doped MOF CuCoSe@HCNF nanostructure possesses excellent electrochemical activity toward the OER with an overpotential of 260 mV @ 20 mA cm−2, HER with an overpotential of 181 mV @ 10 mA cm−2, and ORR E1/2 with a potential of 0.756 V vs RHE. The outstanding activities of the Fe-doped MOF CuCoSe@HCNF nanostructure are mainly due to their distinctive structural features, leading to favorable electron transfer between the electrode and electrolyte interface to achieve successful trifunctional water splitting electrocatalysis.

Simple design of a Si–Sn–C ternary composite anode for Li-ion batteries

Previous research established that Si–Sn–C ternary composite electrodes composed of carbon nanofibers (CNFs) having robust double-hole structures filled with Si and SnOx nanoparticles displayed excellent electrochemical performance due to the thermodynamic contribution of Sn. This study reports simple and highly commercial ternary composite electrodes. By electrospinning and subsequent thermal treatment, Si and Sn nanoparticles were dispersed in solid CNFs to form Si–Sn–SC nanofibers, or they were incorporated into a core of hollow CNFs to form Si–Sn−HC nanofibers. The rate performances of these two ternary electrodes displayed quite good retention because of the ternary composition, but their rate performances differed at high current densities (5000 and 10,000mAg–1); the core/shell structure of the Si–Sn−HC nanofibers was more beneficial for rate performance retention than the Si–Sn–SC nanofibers having intimate electrical contact of Sn and Si with the carbon matrix. Improved cycling performances also resulted from the structure of the Si–Sn−HC nanofibers. The core/shell structured Si–Sn–C ternary composite anode thus has an advantageous structure for high-power Li-ion batteries having long-term stability.

Sustainable Bio-Energy Production in Microbial Fuel Cell Using MnO2 Nanoparticle-Decorated Hollow Carbon Nanofibers as Active Cathode Materials

The widespread use of renewable energy remains a challenging and complex multidisciplinary problem. Developing alternatives using new technology such as nanotechnology is necessary to increase renewable energy’s scalability. Microbial fuel cells (MFCs) combined with nanotechnology can improve bioelectricity generation during wastewater treatment. In this study, hollow carbon nanofibers (H-CNF) were decorated with manganese oxide (MnO2) via a simple chemical reduction method. MnO2-decorated H-CNF prepared with varying concentrations of manganese precursor (MnO2@H-CNF) were characterized via different spectroscopic and microscopic techniques. The cathode catalyst performance of the MnO2@H-CNF was investigated in an //-type constructed MFC system using Shewanella Oneidensis MR1. The MnO2@H-CNF-1 in the assembled MFC displayed excellent power density of 25.7 mW/m2, which is higher than pure H-CNF (8.66 mW/m2), carbon cloth (5.10 mW/m2), and MnO2@H-CNF-3 (16 mW/m2). The maximum power generated in the MFC coupled with MnO2@H-CNF as a cathode catalyst may have been due to the synergistic effect of the MnO2@H-CNF, which increased the electric conductivity and catalytic activity in the MFC’s cathode chamber. These results demonstrate that the developed MnO2@H-CNF cathode catalyst could improve the MFC’s performance and reduce the operational costs of practical applications.

Fabrication of 3D ordered needle-like polyaniline@hollow carbon nanofibers composites for flexible supercapacitors

Carbon nanofiber-based supercapacitors have broad prospects in powering wearable electronics owing to their high specific capacity, fast charge/discharge process, along with long-cycling life. Herein, a poly(acrylonitrile-co-β-methylhydrogen itaconate) copolymer was prepared and used to synthesize flexible hollow carbon nanofibers (HCNFs) via an electrospinning method without breaking after multiple bending. Subsequently, the inner and outer surfaces of HCNFs were evenly covered with ordered needle-like polyaniline (PANI) through in-situ polymerization methods to obtain three-dimensional flexible HCNFs/PANI composites, which exhibited a high capacity 1196.7 F/g at 1 A/g and good cycling stability (90.1% retention at 5 A/g after 3000 cycles). The symmetrical supercapacitor based on the HCNFs/PANI composites also delivered an outstanding electrochemical performance with high energy/power density (60.28 Wh/kg at 1000 W/kg) and superior cycling durability (90% capacitance retention after at 5 A/g 3000 cycles), which confirmed that the HCNFs/PANI composites had a wide application potential in flexible energy storage devices.

Stable bismuth phosphosulfide nanoparticle encapsulation into hollow multi-channel carbon nanofibers toward high performance sodium storage

Both the unique hollow multi-channel structure and inherent merits of nanosized BiPS4 provide the as-formed BiPS4@MCNF nanoarchitecture with outstanding cycling stability and outstanding rate performance.

Predictable interfacial mass transfer intensification of Sn–N doped multichannel hollow carbon nanofibers for the CO2 electro-reduction reaction

Construction of controllable multichannel and mesoporous structures on Sn and N co-doped carbon nanofibers enables intensified interfacial CO2 transfer and stabilized high-loading CO2,ads, enhancing CO2 electro-reduction performance.

Multilevel structured carbon film as cathode host for Li-S batteries with superhigh-areal-capacity

The commercialization of lithium-sulfur (Li-S) battery could be accelerated by designing advanced sulfur cathode with high sulfur utilization and stable cycle life at a high sulfur loading. To allow the energy density of Li-S batteries comparable to that of commercial Li-ion batteries, the areal capacity of sulfur cathode should be above 4 mA·h·cm−2. In general, a high sulfur loading often causes rapid capacity fading by slowing electron/ion transport kinetics, catastrophic shuttle effect and even cracking the electrodes. To address this issue, herein, a multilevel structured carbon film is built by covering highly conductive CNTs and hollow carbon nanofiber together with carbon layer via chemical vapor deposition. The self-standing carbon film exhibits well-interweaved conductive network, hollow fibrous structure and abundant N, O co-doped active sites, which combine the merits of high electronic conductivity (1200·S·m−1), high porosity and polar characteristic in one host. Benefiting from this attractive multilevel structure, the obtained sulfur cathode based on the carbon film host shows an ultra-high areal capacity of 8.9 mA·h·cm−2 at 0.2 C with outstanding cyclability over 60 cycles. This work shed light on designing advanced sulfur host for Li-S batteries with high areal capacity and high cycle stability, and might make a contribution to the commercialization of Li-S batteries.

Porous nitrogen-enriched hollow carbon nanofibers as freestanding electrode for enhanced lithium storage

One-dimensional porous carbons bearing high surface areas and sufficient heteroatom doped functionalities are essential for advanced electrochemical energy storage devices, especially for developing freestanding film electrodes. Here we develop a porous, nitrogen-enriched, freestanding hollow carbon nanofiber (PN-FHCF) electrode material via filtration of polypyrrole (PPy) hollow nanofibers formed by in situ self-degraded template-assisted strategy, followed by NH3-assisted carbonization. The PN-FHCF retains the freestanding film morphology that is composed of three-dimensional networks from the entanglement of 1D nanofiber and delivers 3.7-fold increase in specific surface area (592 m2·g−1) compared to the carbon without NH3 treatment (FHCF). In spite of the enhanced specific surface area, PN-FHCF still exhibits comparable high content of surface N functionalities (8.8%, atom fraction) to FHCF. Such developed hierarchical porous structure without sacrificing N doping functionalities together enables the achievement of high capacity, high-rate property and good cycling stability when applied as self-supporting anode in lithium-ion batteries, superior to those of FHCF without NH3 treatment.

ZIF-67-derived Co nanoparticles anchored in N doped hollow carbon nanofibers as bifunctional oxygen electrocatalysts

Developing highly active and robust bifunctional non-precious oxygen electrocatalysts for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is of paramount importance for enhancing the efficiency of zinc-air battery. Herein, Co nanoparticles anchored in N doped hollow and porous carbon nanofibers (CoN-HPCNF) are obtained via an in-situ growth-pyrolysis approach with the hybrid of ZIF-67 and carbon nanofibers as the precursor. Originating from its high surface area, firm and hierarchical porous structure, effective doping of N as well as synergistic effect from Co nanoparticles and HPCNF, the optimized CoN-HPCNF shows prominent bifunctional catalytic activity and long-term stability toward OER and ORR. Importantly, the assembled aqueous zinc-air battery with the prepared catalyst as the air cathode delivers a peak power density of 126.6 mW cm−2 and narrow charge-discharge voltage gap together with excellent operation durability (more than 280 h at the current density of 5 mA cm−2), outdoing the commercial precious metal catalysts (Pt/C + IrO2).

Hollow carbon nanocapsules-based nitrogen-doped carbon nanofibers with rosary-like structure as a high surface substrate for impedimetric detection of Pseudomonas aeruginosa

The design of hollow mesoporous carbon-based materials has attracted tremendous attention, due to their sizeable intrinsic cavity to load specific chemical and unique physical/chemical properties in various applications. Herein, we have established an effective strategy for the preparation of novel hollow carbon nanocapsules-based nitrogen-doped carbon nanofibers (CNCNF) with rosary-like structure. By embedding ultrafine hollow carbon nanocapsules into electrospun polyacrylonitrile (PAN) skeleton, the as-designed composite CNFs were carbonized into hierarchical porous CNFs, consisted of interconnected nitrogen-doped hollow carbon nanocapsules. Due to its individual structural properties and unique chemical composition, the performance of CNCNF was evaluated in aptasensor application via the detection of Pseudomonas aeruginosa (PA). Under optimized conditions, the aptasensor based on CNCNF has a detection limit of 1 CFU⋅mL−1 and a linear range from 101 CFU ⋅mL−1 to 107 CFU ⋅mL−1 (n = 3). Moreover, the designed aptasensor possesses high sensivity, high selectivity, low detection limit, and high reproducibility. These studies showed that the CNCNF material offers a wide variety of enhanced electrochemical features as an electrode material for aptasensor application.

Rational synthesis of silicon into polyimide-derived hollow electrospun carbon nanofibers for enhanced lithium storage

Abstract Flexible energy devices with high energy density and long cycle life are considered to be promising applications in portable electronics. In this study, silicon/carbon nanofiber (Si@CNF) core–shell electrode has been prepared by the coaxial electrospinning method. The precursors of polyimide (PI) were for the first time used to form the core–shell structure of Si@CNF, which depicts outstanding flexibility and mechanical strength. The effect of doping concentrations of silicon (Si) nanoparticles embedded in the fiber is investigated as a binder-free anode for lithium-ion batteries. A 15 wt% doped composite electrode demonstrates superior performance, with an initial reversible capacity of 621 mA h g−1 at the current density of 100 mA g−1 and a high capacity retention up to 200 cycles. The excellent cycling performance is mainly due to the carbonized PI core–shell structure, which not only can compensate for the insulation property of Si but also has the ability to buffer the volume expansion during the repeated charge–discharge process.

MoS2 Nanosheets Functionalized Multichannel Hollow Mo2N/Carbon Nanofibers as a Robust Bifunctional Catalyst for Water Electrolysis

Herein, a heterogeneous system composed of few-layered MoS2 nanosheets functionalized multichannel hollow carbon nanofibers containing Mo2N (Mo2N-MoS2 MCNFs) was successfully developed for the hydr...

Hollow multi-nanochannel carbon nanofibers@MoSe2 nanosheets composite as flexible anodes for high performance lithium-ion batteries

Herein, three flexible 3D-interconnected N-doped carbon nanofibers (NCFs), multi-nanochannel carbon nanofibers (NMCFs) and hollow multi-nanochannel carbon nanofibers (NHMCFs) networks were prepared through simple electrospinning, then ultrathin MoSe2 nanosheets were vertically grown on the surface of carbon nanofibers (both inner and outer surface for NHMCFs) using a facial hydrothermal method. The resultant MoSe2 composites were directly employed as freestanding anodes for LIBs without any additives. The effect of carbon nanofiber structure on LIBs is studied in detail. The 3D networks of carbon nanofiber provide a continuous electrons transportation pathway, and the multi-nanochannel structure in NMCFs and NHMCFs can alleviate the volume changes during charge–discharge process. Both the inner and outer surfaces of NHMCFs are uniformly coated by MoSe2 nanosheets, thus the mass loading of MoSe2 in NHMCFs/MoSe2 increases 21.25% and 13.85% compared with NCFs/MoSe2 and NMCFs/MoSe2 electrode, respectively. The robust hollow multi-nanochannel structure of NHMCFs can not only increase the contact area between active materials and electrolytes but also shorten the Li+ diffusion pathway. Therefore, the NHMCFs/MoSe2 delivers the highest capacity of 586.7 mAh g−1 among three electrodes after 400 cycles at 1 A g−1, which is 3.54 times of NCFs/MoSe2 and 2.49 times of NMCFs/MoSe2, confirming that NHMCFs is a promising electrode substrate for LIBs.

Ultrathin honeycomb-like MnO2 on hollow carbon nanofiber networks as binder-free electrode for flexible symmetric all-solid-state supercapacitors

Carbon nanofiber-based supercapacitors hold great promise for powering wearable electronics due to their high specific density, fast charge/discharge rate and ultralong cycling life. However, the most common polyacrylonitrile-based carbon nanofiber (CNF) is fragile and easy to break, which limits their practical application. Herein, a poly(acrylonitrile-co-β-methylhydrogen itaconate) copolymer is synthesized and used as precursor to prepare flexible hollow carbon nanofiber (HCNF) by coaxial electrospinning, which can be bended freely without breaking. Then, the ultrathin honeycomb-like MnO2 is coated uniformly on the inner and outer surface of HCNF by in-situ reduction method to prepare freestanding flexible 3D HCNF/MnO2 networks. The HCNF/MnO2 electrode exhibits high capacity 587.5 F g−1 at 0.5 A g−1 and good cycling stability 78.96% retention after 5000 cycles. The HCNF/MnO2 composite is directly utilized to fabricate symmetric all-solid-state symmetric supercapacitors (ASSCs) without using any current collector or binders. The ASSC exhibits a maximum specific energy of 59.15 Wh kg−1 at a specific power of 1575 W kg−1. Four ASSC in series can power a ‘DHU’ Logo consisted of 36 light emitting diodes, confirming the lightweight flexible HCNF/MnO2 based flexible ASSCs have great potential application in wearable and portable electronics.

Molybdenum Carbide-Embedded Multichannel Hollow Carbon Nanofibers as Bifunctional Catalysts for Water Splitting.

With the environmental pollution and non-renewable fossil fuels, it is imperative to develop eco-friendly, renewable, and highly efficient electrocatalysts for sustainable energy. Herein, a simple electrospinning process used to synthesis Mo2 C-embedded multichannel hollow carbon nanofibers (Mo2 C-MCNFs) and followed by the pyrolysis process. As prepared lotus root-like nanoarchitecture could offer rich porosity and facilitate the electrolyte infiltration, the Mo2 C-MCNFs delivered favourable catalytic activity for HER and OER. The resultant catalysts exhibit low overpotentials of 114 mV and 320 mV at a current density of 10 mA cm-2 for HER and OER, respectively. Furthermore, using the Mo2 C-MCNFs catalysts as a bifunctional electrode toward overall water splitting, which only needs a small cell voltage of 1.68 V to afford a current density of 10 mA cm-2 in the home-made alkaline electrolyzer. This interesting work presents a simple and effective strategy to further fabricating tunable nanostructures for energy-related applications.

Highly active Fe7S8 encapsulated in N-doped hollow carbon nanofibers for high-rate sodium-ion batteries

NHCFs/Fe 7 S 8 is rationally designed by combining high active Fe 7 S 8 with high conductivity N-doped carbon. The robust structure with hollow carbon fibers and ultrathin carbon coating layer enables improved charge transfer kinetics and relieved volume expansion. • The Fe/S atomic ratio in iron sulfides controls sodium-ion storage property. • Fe 7 S 8 endows high electron conductivity, reaction reversibility and Na + transport. • The structure with an ultrathin carbon coating layer to protect the Fe 7 S 8 . • The NHCFs/Fe 7 S 8 as electrode shows high-rate capability in DME electrolyte. Nanostructured iron sulfides are regarded as a potential anode material for sodium-ion batteries in virtue of the rich natural abundance and remarkable theoretical capacity. However, poor rate performance and inferior cycling stability caused by sluggish kinetics and volume swelling represent two main obstacles at present. The previous research mainly focuses on nanostructure design and/or hybridizing with conductive materials. Further boosting the property by adjusting Fe/S atomic ratio in iron sulfides is rarely reported. In this work, Fe 7 S 8 and FeS 2 encapsulated in N-doped hollow carbon fibers (NHCFs/Fe 7 S 8 and NHCFs/FeS 2 ) are constructed by a combined chemical bath deposition and subsequent sulfidation treatment. The well-designed NHCFs/Fe 7 S 8 electrode displays a remarkable capacity of 517 mAh g −1 at 2 A g −1 after 1000 cycles and a superb rate capability with a capability of 444 mAh g −1 even at 20 A g −1 in ether-based electrolyte. Additionally, the rate capability of NHCFs/Fe 7 S 8 is superior to that of the contrast NHCFs/FeS 2 electrode and also much better than the values of the most previously reported iron sulfide-based anodes. The in-depth mechanism explanation is explained by further experimental analysis and theoretical calculation, revealing Fe 7 S 8 displays improved intrinsic electronic conductivity and faster Na + diffusion coefficient as well as higher reaction reversibility.