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In this work, we have prepared the hierarchically nanostructured core–shell NiCo layered double hydroxide (NiCo-LDH) nanosheets- and ZnFe2O4 nanocubes-decorated polyacrylonitrile (PAN)/pitch-based carbon nanofibers (PPCNs) webs (NiCo-LDH@PPCNs as cathode and ZnFe2O4@PPCNs as anode materials) with the bonded network structure by a facile and scalable hydrothemal method. Herein, the low-cost pitch with lower softening point (∼90 °C) as co-precursor was utilized to produce the PAN/pitch-based carbon nanofibers (PPCNs) with enhanced electrical conductivity. The obtained PPCNs with pitch content of 30% (PP30CNs) electrode material delivered higher specific capacitance (∼67 F g−1) than that (∼48 F g−1) of the PAN-based carbon nanofibers (PCNs) at 1 A g−1, due to the increased electrical conductivity and lower interfacial charge transfer resistance (RCT) of ∼0.16 Ω. Further, the NiCo-LDH-decorated PP30CNs (NiCo-LDH@PP30CNs) as cathode material showed superior specific capacitance of 1162 F g−1 at 1.0 A g−1 and ultra-high retention rate of 91.56% at 10 A g−1. The ZnFe2O4@PP30CNs as anode material also showed higher specific capacitance of 282 F g−1 at 1 A g−1 and good rate capability with capacitance retention of 56.73% at 10 A g−1. The as-fabricated asymmetric NiCo-LDH@PP30CNs//ZnFe2O4@PP30CNs hybrid supercapacitor device delivered a specific capacitance of ∼98 F g−1 at 1 A g−1 and excellent capacitance retention of ∼88% after 5000 charge–discharge cycles.

Development of methane dry reforming catalyst is very important for economical production of syngas from CH4 and CO2 and reduction of greenhouse gases. Ni-based hydrotalcite derived spinel catalysts were synthesized for dry reforming of methane (DRM). Properties of the catalyst such as reducibility, basicity, morphology, texture and crystal structure, had a great impact on catalyst’s activity and stability. Superior catalytic activity and stability during DRM process was achieved with the formation of hydrotalcite derived spinel (NiAl2O4) structures, eruption of carbon nanofibers (CNFs) from carbon layer, and formation of Ni0 active sites on the tips of these CNFs. The Ni particles from reduction of NiO and NiAl2O4 evolved on top of the CNFs and provided a strong metal–support interactions resulting in high resistance against sintering and coking at 850 °C during the long-term DRM process (200 h).

Rational design of hybrid electrocatalysts of nanostructured non-precious metals/metal compound on highly conductive substrates is significant to enhance oxygen reduction activity for clean energy conversion. However, the limited exposure of active sites and sluggish mass transport on electrode trade-off the intrinsic performance of electrocatalyst. Herein, we report a strategic method to fabricate electrocatalyst with well-dispersed iron-based mixed nanoparticles embedding in nitrogen-doped carbon nanofibers (Fe-Fe3C/Fe3N@NCNFs) and demonstrate desired properties of the material, such as hierarchically porous structure, large specific surface area, and well-dispersion of mixed nanoparticles. The Fe-Fe3C/Fe3N@NCNFs electrocatalyst also exhibits high-performed activity in oxygen reduction reaction (ORR) with high onset potential of 0.998 V and half wave potential of 0.85 V, as well as high stability and methanol tolerance, which is even superior to benchmark performance of commercial Pt/C. In addition, a zinc-air battery assembled with Fe-Fe3C/Fe3N@NCNFs as the air cathode shows high open-circuit voltage (1.466 V), high specific capacities (778 mA h g−1 at 5 mA cm−2), excellent reversibility and stability. The remarkable improvement of electrocatalytic performance validates paramount advantages, attributing from the inter-connected conduction network and well-dispersed active sites on carbon nanofiber surface, over mass transfer process and maximizing exposure of catalytic sites

Self-supported transition-metal single-atom catalysts (SACs) facilitate the industrialization of electrochemical CO2 reduction, but suffer from high structural heterogeneity with limited catalytic selectivity. Here we present a facile and scalable approach for the synthesis of self-supported nickel@nitrogen-doped carbon nanotubes grown on carbon nanofiber membrane (Ni@NCNTs/CFM), where the Ni single atoms and nanoparticles (NPs) are anchored on the wall and inside of nitrogen-doped carbon nanotubes respectively. The side effect of Ni NPs was further effectively inhibited by alloying Ni with Cu atoms to alter their d-band center, which is theoretically predicted and experimentally proved. The optimal catalyst Ni9Cu1@NCNTs/CFM exhibits an ultrahigh CO Faradic efficiency over 97% at −0.7 V versus reversible hydrogen electrode. Additionally, this catalyst shows excellent mechanical strength which can be directly used as a self-supporting catalyst for Zn-CO2 battery with a peak power density of ∼0.65 mW/cm2 at 2.25 mA/cm2 and a long-term stability for 150 cycles. This work opens up a general avenue to facilely prepare self-supported SACs with unitary single-atom site for CO2 utilization.

Thanks to inexpensive and bountiful potassium resources, potassium ion batteries (PIBs) have come into the spotlight as viable alternatives for next-generation battery systems. However, poor electrochemical kinetics due to the large size of the K+ is a major challenge for PIB anodes. In this paper, an ingenious design of VN nanoparticle-assembled hollow microspheres within N-containing intertwined carbon nanofibers (VN-NPs/N-CNFs) via an electrospinning process is reported. Employed as PIB anodes, VN-NPs/N-CNFs exhibit a superb rate property and prolonged cyclability, surpassing that of other reported metal nitride-based anodes. This is ascribed to: (i) the VN NP-assembled hollow microspheres, which shorten the K+ diffusion distance, and mitigate volume expansion; and (ii) the interconnected N-CNFs, which supply numerous active sites for K+ adsorption and facilitate rapid electron/ion transport.

In this study, Ni/Al2O3 was prepared with an impregnation method for CO2 hydrogenation into carbon nanofibers (CNFs). High purity CNFs were acquired from CO2 hydrogenation at 500 °C and 1 atm over Ni/Al2O3 catalyst after a liquid phase extraction process, removing the used catalysts and by-products. The particle properties of as-prepared Ni/Al2O3 have been well characterized for comparison with the commercial ones. The results of XPS spectra and XRPD patterns indicated that the commercial, as-prepared, and used Ni/Al2O3 were multicomponent with various crystal phases. The as-prepared Ni/Al2O3 can be sufficiently exposed in CO2 atmosphere for higher catalytic performances owing to its unique microstructure with higher specific surface area (429.2 m2/g). Both EXAFS and XANES spectra have shown that the first shell of Ni atom in commercial, as-prepared, and used Ni/Al2O3 were Ni O with bond distances of 1.61, 1.63, and 1.62 A, respectively. The configuration of fabricated CNFs was characterized by its unique ID/IG (Intensities of D-band/G-band) ratio of 0.23 in the Raman spectrum. Solid tubular shape with 30 nm diameter of CNFs was observed using FE–SEM and HR–TEM. Thermodynamic analyses indicate that CO2 hydrogenation into CNFs is a spontaneous and exothermic reaction with an optimal temperature of 500 °C.

The uncontrollable Li dendritic plating and infinite volumetric expansion significantly plague the practical applications of lithium (Li) metal, which is regarded as the most promising high-energy-density anode material for rechargeable batteries. The well regulated Li-ion (Li+) flux distribution and Li deposition is the prerequisite for feasible Li-metal batteries. In this work, the Li migration, nucleation and growth behavior are investigated with a lithiophilic CoP-doped carbon nanofibers (CoP@CNF)-guided self-standing substrate. The high adsorption effect and low migration barrier of CoP to Li+ lead to the reversible conversion reaction between Li and CoP, enabling an even charge transportation and a homogeneous Li+ concentration gradient. The uniform nucleation and dense electrodeposition of Li over through the CoP@CNF is demonstrated via combined in-situ/ex-situ morphologic and electrochemical characterizations. Benefiting from the small nucleation and growth overpotential of Li, the symmetrical cell of CoP@CNF@Li can steadily operate under 0.5 mA cm−2 over 2000 h with a low voltage hysteresis of ca. 12 mV. When paired with a LiFePO4 cathode, a specific capacity exceeding 90 mAh g−1 up to 1000 cycles is achieved at 5 C (1 C = 170 mA g−1), demonstrating the dendritic Li suppression capability of the CoP@CNF@Li composite anode.

We synthesized herein a novel 3D cathode constructed by growing cobalt diselenide in situ on the surface of carbon nanofiber for hydrogen evolution reaction. The cobalt diselenides with two typical morphologies (agaric-like and nanorod-like) were synthesized by precisely controlling reaction time and temperature in the same system. They show excellent electrocatalytic performance for hydrogen evolution reactions. Especially, the agaric-like diselenide cobalt electrode has the low overpotential (187 and 199 mV) to obtain the current density of 50 and 100 mA cm-2 with a small Tafel slope of 37 mV dec−1 in acidic medium. The excellent catalytic performance of the agaric-like cobalt diselenide can be attributed to its large specific surface area and fast electron transfer rate. More importantly, the agaric-like cobalt diselenide supported carbon nanofiber electrode has excellent long-term stability in electrolyte. The outstanding electrocatalytic performance and stability of agaric-like cobalt diselenide supported carbon nanofiber indicate that it is a promising electrocatalyst for hydrogen evolution reactions.

Ceramic SiCN nanocomposites modified with nanocellulose derived defect-rich carbon nanofibers (CNFs-SiCN) were developed by thermolysis of nanocelulose-polysilazane single-source precursors (SSPs). Multi-loss mechanisms (i.g. polarization loss and conductive loss) were established in the SiCN ceramic nanocomposites by employing the defect-rich structure of CNFs. Cole-Cole circle plots indicate that the CNFs-SiCN ceramics possess strong polarization capability due to the defect-rich structure of the CNFs. Dielectric loss values fitted by the Debye theory showed that the proportion of polarization loss reaches an unprecedented high value, accounting for 52.1% of the total dielectric loss. When the content of nanocellulose is 10 wt.% of SSPs, the minimal reflection coefficient (RCmin) and effective absorption bandwidth (EABs) of CNFs-SiCN ceramic can reach −36.3 dB and 3.0 GHz, respectively. This work may contribute new ideas for establishing multi-loss mechanisms in ceramic-based materials, finding a new application for nanocellulose, and shaping the design of novel absorbents.

Design of high energy density lithium storage materials is one of the everlasting issues in energy storage systems to realize a fully clean and sustainable energy grid. Here, 2,9-dimethyl quinacridone was selected as a precursor to prepare carbon-based electrode via low temperature heat-treatment process from 750 °C to 1050 °C. The pyro-polymerization of 2,9-dimethyl quinacridone induced a distinctive morphological transformation from rice husk-shaped 2,9-dimethyl quinacridone to carbon nanofibers. Electrode fabricated from pigment derived carbon nanofibers (PCNF) pyrolyzed at 750 °C maintained 878 mAh g-1 at a current density of 1 A g-1 and good Coulombic efficiency up to 98% after 1000 cycles. Furthermore, it delivered 337 mAh g-1 at a high current density of 25 A g-1. The superior performance was attributed to the stable structure of pristine 2,9-dimethyl quinacridone giving high thermal stability and crystallinity owing to well-defined π-π and hydrogen bonding interactions, thus rendering a stable microstructure with a large d-spacing of (002) plane of 3.580 A, as well as efficient surface redox reactions. Density functional theory calculations indicated that the large interlayer distance could facilitate fast lithium ion insertion/extraction because of a ∼38% lower energy barrier for lithium ion insertion than compared with graphite.

The elaborative design and construction of first-rank bifunctional oxygen electrocatalysts featuring low price, high activity and strong stability is critical for the large-scale applications of rechargeable Zn-air batteries. Here, a resultful strategy is proposed for fabricating nitrogen-doped 1D beaded-like structure carbon nanofibers uniformly decorated with nitrogen-doped CuCo2O4 nanoparticles (N-CuCo2O4@CNFs) toward boosting oxygen evolution reaction/oxygen reduction reaction (OER/ORR) catalysis. Taking advantage of the synergistic effect between interconnected 1D hierarchical porous carbon nanofiber structure and high catalytic activity of N-doped CuCo2O4 nanoparticles derived from bimetallic MOFs, the N-CuCo2O4@CNFs catalysts possess enhanced reaction kinetics and preferable charge transfer ability. Impressively, the obtained catalysts exhibit prominent electrocatalytic ability and superior stability for OER/ORR, even surpass the commercial RuO2 and Pt/C. More significantly, the Zn-air batteries employing the N-CuCo2O4@CNFs-800 as cathode display a higher power density of 175.6 mW cm−2, a lower charge-discharge voltage gap of 0.82 V at 10 mA cm−2, as well as a better cycling stability with respect to those of Pt/C + RuO2 mixture, demonstrating the great potential of N-CuCo2O4@CNF as a high-efficiency catalyst for clean energy devices.

Capacitive deionization (CDI) technology is proposed as an environmentally friendly way to desalinate brackish water samples with outstanding efficiency. Since the nanomaterial composition is the controlling factor in the measured activity of fabricated CDI cells, much efforts are directed to explore highly effective nanocomposites with increased electrosorptive capacity and enhanced regeneration behavior during operation for longer periods. Here, the electrospinning process was devoted to synthesize mixed cobalt and titanium carbides nanoparticles onto carbon nanofibers [Co–TiC@CNFs] using cobalt acetate tetrahydrate (CoAc) and titanium (IV) isopropoxide (TIP) as precursor salts and polyvinylpyrrolidone (PVP) as a carbon source. Electrospun mats were then calcined at 950 °C for 6 h using a tube furnace with passing argon gas. This formed nanoporous material could provide numerous pathways for increased ions adsorption with extraordinary electrical conductivity. This could explain its enhanced electrochemical properties as evidenced by cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy (EIS) methods. A specific capacitance value of 979.40 F g−1 was estimated for Co–TiC@CNFs as 7.42 times higher than that for bare CNFs. Furthermore, this nanohybrid material had a salt adsorption capacity of 33.10 mg g−1 in 1.0 M NaCl solution at 1.2 V that highly exceeded the obtained ones for TiC [2.20 mg g−1] and CNFs [8.20 mg g−1]. Accordingly, modifying carbon nanofibers with metallic carbides can create suitable nano-constituents for promising CDI cell output.

Lithium-sulfur (Li-S) batteries have attracted extensive attention in the field of energy storage due to their high energy density and low cost. However, conundrums such as severe polarization, poor cyclic performance originating from shuttle effect of lithium polysulfides and sluggish sulfur redox kinetics are stumbling blocks for their practical application. Herein, a novel sulfur cathode integrating sulfur and polyvinylpyrrolidone(PVP)-derived N-doped porous carbon nanofibers (PCNFs) with embedded CoF3 and YF3 nanoparticles are designed and prepared though the electrostatic blowing technology and carbonization process. The unique flexible PCNFs with embedded polar CoF3 and YF3 nanoparticles not only offer enough voids for volume expansion to maintain the structural stability during the electrochemical process, but also promote the physical encapsulation and chemical entrapment of all sulfur species. Moreover, the uniform distribution of YF3/CoF3 nanoparticles also can expose more binding active sites to lithium polysulfide and present more catalytic sites to the greatest extent. Therefore, the assembled cells with the prepared cathode exhibited stable performances with an outstanding initial capacity of 1055.2 mAh g−1 and an extended cycling stability of 0.029% per cycle during the 300 cycles at 0.5C. Even at a high sulfur loading of 2.1 mg cm−2, The YF3/CoF3 doped-PCNFs exhibited a high discharge specific capacity of 1038 mAh g−1, and the decay rate is also as low as 0.05% over 1000 cycles. This work shares a convenient and safe strategy for the synthesis of multi-dimension, dual-functional and stable superstructure electrode for advanced Li-S batteries.

Tin dioxide (SnO2) is a promising anode material for lithium-ion and sodium-ion batteries. However, the huge volume expansion during cycling makes it far away from practical application. Herein, we report a template-free “heterogeneous carbonization” strategy for fabricating SnO2/carbon/void/carbon nanofiber (SCVC) compound membrane with finite spatial domain in carbon matrix as buffer layer for volume changes of SnO2. Reduced graphene oxide (rGO) is also imported into the SCVC membrane, acting as conductive binders to construct a free-standing SCVC-rGO electrode with exceptionally conductive network. The resultant SCVC-rGO anodes in lithium/sodium-ion batteries could deliver excellent electrochemical performances of higher reversible capacity, longer lifespan and superior rate capability. As lithium-ion battery anode, the SCVC-rGO electrode shows specific capacities of 950 mA h g−1 after 400 cycles at a current of 0.5 A g−1, and 824 mA h g−1 after 650 cycles at 1 A g−1. In sodium-ion batteries, the SCVC-rGO electrode gives rise to the specific capacity of 407 mA h g−1 after 2000 cycles at the current of 1 A g−1 with exceptional capacity retention.

Metal oxides are prospective alternative anode materials to the commercial graphite for lithium ion batteries (LIBs), while their practical application is seriously hampered by their poor conductivities and large volume changes. Herein, we report the controllable synthesis of amorphous/crystalline MnCo2Ox nanoparticles within porous carbon nanofibers (marked as MCO@CNFs) through a facile electrospinning strategy and subsequent annealing reactions. The phase structures from Co/MnOX to amorphous MnCo2Ox and crystalline MnCo2O4.5 can be readily tuned by thermal reduction/oxidation under controlled atmosphere and temperature. When examined as anode for LIBs, the optimized MCO@CNFs delivers a high stable capacity of 780.3 mA h g−1 at 200 mA g−1 after 250 cycles, which is attributed to the synergistic effect of the distinctive amorphous structure and defective carbon nanofiber matrices. Specifically, the amorphous structure with rich defects offers more reactive sites and multiple pathways for the Li+ diffusion, while carbon hybridization sufficiently improves the electrode conductivities as well as buffers the volume changes. More importantly, we demonstrate a convenient synthesis strategy to control the metal-to-oxide structure evolution within carbon matrices, which is of great importance in exploring high-performance electrodes for next generation LIBs.

Prussian blue analogs, as a pseudo-capacitor electrode materials hold great potential due to their unique framework structure, excellent electrochemical activity and high specific capacity. Herein, a versatile method for the growth of series of metal hexacyanoferrates (MHCF) on carbon nanofiber with high conductivity and flexibility was proposed. By controlling the releasing rate of metal ions through acid modulation of solution, the series of MHCF nanocubes were successfully embedded on the carbon nanofibers with super stability. Different MHCF presented various loading density. Among the MHCFs, nickel hexacyanoferrate (NiHCF) is the most easily formed with high density and uniform distribution. The obtained self-supporting NiHCF@CNF, as a representative electrode, exhibited high specific capacitance (507 F g−1, 1 A g−1) and remarkable rate performance (67% retention at 10 A g−1). Moreover, the NiHCF@CNF-based hybrid supercapacitor cell delivered a high energy density of 60 Wh kg−1 at the power density of 810 W kg−1. Meanwhile, the capacitor showed extremely high stability due to tight anchoring of NiHCF on CNFs. This work provides a simple and versatile method to produce self-supporting MHCF@CNF composites for constructing high performance supercapacitor.

Oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) involve proton coupled electron transfer reaction (PCET), resulting in sluggish redox kinetics. At present, the development of high-efficiency bifunctional oxygen electrocatalysts is still a puzzling challenge. Here, we propose a scalable strategy for embedding and beading ZIF-derived hollow Co-Nx nanocube cages dispersion implanting with porous carbonized nanofibers (EH/PCNFs and BH/PCNFs) through electrospinning and annealing. The cobalt species prevent themselves from agglomerating during the annealing process through the “fence” effect of the non-volatile Zn species, thereby synergizing with ligand volatilization to facilitate the formation of Co-Nx nanocube cages. Benefiting from the ultralong interconnected multi-layered carbon nanofiber matrix, the hollow Co-Nx nanocube cages can change the charge density and electron distribution of carbon nanofiber matrix, endowing the carbonized nanofiber carrier with special surface polarization and accelerating the electrocatalytic kinetics. Remarkably, the integrated Li-O2 batteries (LOBs) based on BH/PCNFs and EH/PCNFs electrodes respectively exhibit significantly decreased charge/discharge polarization (0.79 V) and a long-term cyclability (147 cycles) under a cut off capacity of 500 mAh g−1 at 200 mA g−1. This work might be beneficial to the practically viable design and manufacture of dual-function oxygen electrocatalysts.

One dimensional (1D) nanostructure like nanorods, nanowires, nanotubes and nanofibers have aroused great attention owing to their exceptional properties like high surface-to-volume ratio, excellent electron and thermal transport and also plays as interconnects during fabricating nanoscale devices. In this work, one dimensionally aligned Carbon nanofibers(CFs)@AuNPs-PtNPs/NiNPs-PtNPs have been developed via a single step co-axial electrospinning integrated with in-situ photo-reduction. The carbon nanofibers with in-situ functionalized bimetallic nanoparticles possessed well-defined core-shell structure with carbon nanofibers (CFs) as the core and AuNPs-PtNPs/NiNPs-PtNPs as the surface anchored heterojunctions. Homogeneously distributed AuNPs-PtNPs/Ni NPs-Pt NPs, which are identified as chemical sensitizers, triggers the dissociation of H2 through the spill-over effect, by successive diffusion of these H+ on carbon nanofiber surface, thereby altering the entire surface of the CFs into reaction sites for H2. Aligned core-shell CFs@Ni NPs-PtNPs possessed high sensitivity of 124% (v/v) at room temperature as compared with aligned core-shell CFs@PtNPs NPs (52%) and aligned core-shell CFs@AuNPs-PtNPs (65%), which may be due to the high catalytic adsorption and desorption properties of Ni and Pt towards hydrogen gas. Moreover, co-axially aligned CFs@NiNPs-PtNPs based sensor also demonstrates outstanding selectivity towards hydrogen compared to other gases like ammonia, ethanol, hydrogen sulphide, and acetone with excellent long-term stability. In addition, hydrogen adsorption kinetics of co-axially aligned CFs@NiNPs-PtNPs based sensor was verified theoretically the adsorption rate constant of (0.42) which showed a comparable experimental value (0.38) of adsorption rate constant. The potential suitability of co-axially aligned CFs@NiNPs-PtNPs based sensor towards H2 at room temperature leading towards real time applications also have been demonstrated

Stable cycling of potassium metal anodes in classic carbonate electrolytes remains a great challenge. Three-dimensional carbon hosts have been widely adopted to address the low Coulombic efficiency and devastated dendrite growth, but a correlation between the carbon microstructure and potassium plating/stripping stability has yet to be established. Here, stark contrasted carbonization temperatures, i.e., 800 and 2800 °C, are applied to electrospun carbon nanofiber (CNF) films for regulating graphitization degree. The resulted CNFs demonstrate distinct stability when serving as hosts for potassium metal anodes. We reveal that the carbon microstructure has a huge impact on not only the nucleation and diffusion of the K ions but also the mechanical properties of solid electrolyte interphases (SEIs). The maximum elastic deformation energy (U), which reveals the combined effects of Young's modulus and yield strain, is utilized to reflect the capability of SEI in accommodating the electrode deformation upon K deposition. The CNFs prepared at 2800 °C benefit the formation of a high U-value SEI. Consequently, it exhibits a small polarization and an ultra-long life of over 2000 h at 0.5 mA cm−2 in the carbonate electrolyte.

Platinum (Pt) is considered as the most efficient catalyst for hydrogen evolution reaction (HER) with a nearly zero overpotential, but it is limited by the high cost and poor stability. Herein, we report an efficient electrocatalyst of Pt–Ni alloy nanoparticles (NPs) supported on the La-modified flexible carbon nanocomposite fibers (PtNi@La-CNFs) for HER. The rare earth metal oxide in the catalyst has a structure-effect relationship with the carbon fibers to form a flexible fiber membrane. Experimental results show that the macroscopic and microscopic properties of carbon nanocomposite fibers can be optimized by doping La2O3, and the Pt–Ni NPs can be anchored effectively. The Pt1Ni1@La-CNFs electrocatalyst exhibits a small overpotential of 32 mV to achieve current density of 10 mA cm−2 with a low Tafel slope of 51 mV dec−1 in alkaline medium, outperforming that of Pt@La-CNFs and the commercial Pt/C catalyst. This study reveals that the multiple coupling effect of rare earth compound, precious metal, and transition metal in composite catalyst can tailor its the electronic configuration, and results in an enhanced HER performance. This work opens up a novel approach to design high active and low cost Pt-based HER catalysts.

The design of efficient, stable, and economical electrocatalysts for oxygen and hydrogen evolution reaction (OER and HER) is a major challenge for overall water splitting. Herein, a hierarchical structured CoP/carbon nanofibers (CNFs) composite was successfully synthesized and its potential application as a high-efficiency bifunctional electrocatalyst for overall splitting water was evaluated. The synergetic effect of two-dimensional (2D) CoP nanosheets and one-dimensional (1D) CNFs endowed the CoP/CNFs composites with abundant active sites and rapid electron and mass transport pathways, and thereby significantly improved the electrocatalytic performances. The optimized CoP/CNFs delivered a current density of 10 mA cm−2 at low overpotential of 325 mV for OER and 225 mV for HER. In the overall water splitting, CoP/CNFs achieved a low potential of 1.65 V at 10 mA cm−2. The facile strategy provided in the present work can facilitate the design and development of multifunctional non-noble metal catalysts for energy applications.

Given the abundant natural reserves of potassium and its similar properties to lithium, potassium-ion batteries (KIBs) are expected to be an emerging energy storage system to replace lithium-ion batteries (LIBs). Here, to overcome the sluggish diffusion kinetics and structure collapse of the anode in current KIBs, copper tetrathiovanadate (Cu3VS4) nanoparticles uniformly loaded in carbon nanofibers (CVS/CNF) are designed as a new anode for KIBs through electrospinning and subsequent carbonization/sulfidation treatment. Benefiting from the highly conductive Cu species and CNF network, an outstanding charge transfer kinetics is achieved in CVS/CNF composites. Meanwhile, the nanosized CVS particles and robust CNF networks are believed to be beneficial for enhanced structural stability during potassium insertion, and thus endow the composite anode with an excellent long-term capability. The CVS/CNF composite anode displays a high capacity (486 mA h g−1 at 0.1 A g−1), great rate feature (162 mA h g−1 at 6 A g−1) and outstanding cycling performance (193 mA h g−1 after 2000 cycles at 1 A g−1), which are superior to those of most of the reported transition metal sulfide anodes.

Carbon nanofibers (CNFs) thin films were prepared by using Radio frequency assisted plasma enhanced chemical vapor deposition (RF-PECVD) technique. Nickel thin films have been used for preparation of CNFs thin films, which stimulates the growth. The identification and confirmation of the graphitic phase of CNFs thin films were confirmed by using X-Ray Diffractometer. Nanostructure surface morphology of the CNFs thin films have been investigated by an Atomic Force Microscope, which reveals that the typical diameter of the CNFs was ∼ 180 nm with length of several micrometers. The electron field emission properties of CNFs thin films have been carried out for different cathode–anode separation and for various ambient temperatures. It was observed that with the extent of cathode–anode separation from 70 to 210 μm, the turn-on field was reduced to 3.5 V/μm from 4.4 V/μm respectively. Temperature dependent electron field emission measurement showed that the turn-on field was reduced to 2.3 V/μm from 4.2 V/μm, as ambient temperature of CNFs thin films was increased from 30 °C to 250 °C respectively. The field enhancement factor and turn-on field were calculated and demonstrate the electron emission procedure.

The rational design of an excellent architecture for active materials combined with carbon matrix is of particular importance to obtain flexible electrode material with high electrochemical properties. Well-designed nanofibers possess unique 3D network structure, which can significantly improve the electron/ion transportation and supplies sufficient active sites for Li+/Na+ insertion. Electrospinning-carbonization technology is a popular strategy to prepare nanofibers with active material embedded in carbon. It is found that the architecture of nanofibers tended to be wrecked and destroyed during the carbonization process without pre-oxidation treatment. In this study, we prepared Na2MnPO4F particles embedded in carbon nanofibers (Na2MnPO4F/C) using PVP as carbon source and investigated the strengthen mechanism of pre-oxidation on their architecture. The experiment and simulation results demonstrate that, without pre-oxidation, the main chain of PVP is severely ruptured during the carbonization procedure, consequently leads to fractured architecture of Na2MnPO4F/C nanofibers. In contrast, with pre-oxidation treatment, a long-chain and heat-resistance structured carbon matrix formed, and Na2MnPO4F/C nanofibers with stable architecture and improved electrochemical performance can be achieved. This study demonstrates a promising guide to construct carbon based nanofiber electrodes with stable architecture and high electrochemical performance.

In this work, we propose and develop a novel electrode made of aligned microscale carbon fibers interweaved with highly porous carbon nanofibers for vanadium redox flow batteries. Such a unique combination not only endows the electrode with a high permeability due to the reduced tortuosity and large macropores, but also an ultra-large specific surface area for redox reactions. As a result, a vanadium redox flow battery equipped with the newly-developed electrode is able to achieve an energy efficiency of 79.3% at the current density of 400 mA cm−2, which is 9.9% higher than that with pure porous carbon nanofiber electrodes, and 14.1% higher than that with pure aligned fiber electrodes. More remarkably, the battery is capable of delivering a peak power density of as high as ∼1.9 W cm−2 and a limiting current density of ∼5000 mA cm−2. These results demonstrate that our strategy of interweaving porous carbon nanofibers between aligned microfibers effectively addresses the contradiction between permeability and surface area of porous electrodes, opening a new platform to fabricate high-performance electrodes for vanadium redox flow batteries.

In this work, lignin-based carbon nanofibers (LCNFs) were for the first time served as substrate for in-situ electrodeposition of polyaniline (PANI) and tested as pseudocapacitor. Two LCNFs with different lignin ratios were designed to distinguish their morphology and structural properties. Next, PANI deposition mechanisms on both LCNFs were investigated and the electrochemical performance of the resulting LCNF/PANIs were evaluated. It was found although LCNF2 was composed of less uniform nanofibers due to more presence of lignin in precursor dope, it had higher tensile strength/modulus than LCNF1 (strength: 34.3MPa to 24.2 MPa; Modulus: 2.40 GPa to 1.45GPa) and was more cost-effective. Particularly, the beaded fibers on LCNF2 contributes to the deposition of PANI with higher specific mass capacitance (612.8 F g−1 to 547.0 F g−1). Upon assembling into solid-state supercapacitors, the Cm of LCNF2/PANI device was determined to be 229 F g−1 and the maximum energy density was 11.13Wh kg−1 at a power density of 0.08 kW kg−1. This work showed LCNF produced from renewable and low-cost lignin could be directly used as substrate for PANI deposition. Moreover, the composition in spinning dope played an important role in determining the performances of resulting pseudocapacitors.

Metal-organic framework (MOF)-based electrode materials have become a hot subject for supercapaitors. Herein, Ni-MOFs grown on Co nanoparticles modified carbon nanofibers (CNFs) (C-Co@MOF) are prepared via a facile process. Interestingly, the presence of Co nanoparticles in CNFs not only boosts the hybridization of CNF and MOFs, but also releases Co ions to participate in the growth of MOF, leading to a favorable electrochemical behavior. In detail, the specific capacitance of C-Co@MOF reaches 1201.6 F g−1 that exceeds those of C-M@MOFs (M = Ni, V, Mo, Mn, Fe, Cu and Zn) and CNF@MOF. More importantly, an asymmetric solid-state supercapacitor is assembled using C-Co@MOF and nitrogen-doped carbon nanotubes derived from polyaniline as positive and negative electrode materials, respectively, representing a high energy density of 37.0 Wh kg−1 and outstanding durability. This work highlights the superiority of electrospun CNFs modified by metal nanoparticles for the growth of MOF, showing great potential for electrochemical energy storage and conversion applications.

Herein, a red iron oxide @ carbon fiber (RIO@CF) composite is prepared via a simple and effective single hydrothermal and calcination process. The physico-chemical characteristics of as-prepared electrode active materials are examined by X-ray photoelectron spectroscopy, high resolution field emission-scanning electron microscopy and field emission-tunneling electron microscopy analyses. When used as the anode material in the Li-ion battery, as-prepared RIO@CF composite have shown a specific capacity of 1138 mAh g−1 after 150 cycles with a capacity retention of 86% at a current density of 100 mA g−1. Moreover, a specific capacity of 825 mAh g−1 is achieved in the first cycle at a current density of about 5000 mA g−1. Thus, when compared to the pristine nano-cube-like red iron oxide (RIO) electrode material, the RIO@CF composite electrode exhibits an outstanding cyclic stability and rate capacity. This electrochemical enhancement facilitates effective lithium ion transport into the RIO@CF composite electrode, thus improving the electrical conductivity. In addition, the application of a homogeneous carbon fiber coating can provide effective contact between the electrode surface and the electrolyte to further benefit the electrochemical performance.

Background Effective high-throughput strategies to prepare nanostructured electrodes for glucose sensing remain significant interest for many applications. In this study, acicular nickel was immobilized on carbon nanofibers (CNFs) via electroless plating under a magnetic field to form CNFs-Ni, and its application as an electrode in amperometric non-enzymatic glucose sensing was investigated. Methods Polyacrylonitrile (PAN) nanofibers (NFs) were fabricated by centrifuged-electrospinning, in which the combination of electrostatic and centrifugal forces produces a strong stretching force. PAN polymer chains were aligned parallel to the axis of the NFs, thereby stretching the dispersed PAN droplets into thin and molecularly orientated NFs. The PAN NFs were then subjected to stabilization followed by carbonization at 1200, 1300, 1400, or 1500 °C to produce PAN CNFs. The characteristics of the CNFs were confirmed by scanning electron microscopy (SEM), electron spectroscopy for chemical analysis, Raman spectroscopy, and four-point probe analysis. Additionally, the CNFs coated with acicular nickel (CNFs-Ni) were analyzed by SEM, X-ray diffraction, and high-resolution transmission electron microscopy. Significant Findings Under the optimal conditions (CNFs1400-Ni), the glucose sensor showed a high sensitivity (7404 μA mM−1 cm−2) with a linear range from 2.1 × 10−2 to 6.0 × 10−1 mM (R2 = 0.993) and fast response (10 s).

Silicon (Si) is one of the most potential candidates for the next-generation anode material for lithium-ion batteries. Nevertheless, the practical application of Si anode is limited by low conductivity and large volume expansion during charge/discharge processes. Herein, hierarchical Si/C composites are prepared via two-step chemical vapor deposition method and one-step in situ polymerization, in which N-doped carbon-coated Si nanofiber was deposited on carbon nanofiber/natural microcrystalline graphite. Such structural design is beneficial to restrict the volume expansion of Si and enhance the conductivity of electrode material. Moreover, derived silicon carbide at the interface between carbon nanofiber with silicon greatly improves the bonding ability, preventing the separation of Si from carbon fibers. Therefore, the composites can provide a reversible capacity of 528.3 mA h g−1 after 100 cycles at a current density of 100 mA g−1 and display good rate capability (the capacity retention rate is 89.8% after charging and discharging under different currents).

Further development of lithium–sulfur (Li–S) batteries is restricted by the insulation of sulfur and the shuttle effect of lithium polysulfide (LiPSs). Herein, we propose a multifunctional freestan...

Developing affordable and efficient electrocatalysts as precious metal alternatives toward the hydrogen evolution reaction (HER) is crucially essential for the substantial progress of sustainable H2 energy-related technologies. The dual manipulation of coordination chemistry and geometric configuration for single-atom catalysts (SACs) has emerged as a powerful strategy to surmount the thermodynamic and kinetic dilemmas for high-efficiency electrocatalysis. We herein rationally designed N-doped multichannel carbon nanofibers supporting atomically dispersed Mo sites coordinated with C, N, and O triple components (labeled as Mo@NMCNFs hereafter) as a superior HER electrocatalyst. Systematic characterizations revealed that the local coordination microenvironment of Mo is determined to be a Mo-O1N1C2 moiety, which was theoretically probed to be the energetically favorable configuration for H intermediate adsorption by density functional theory calculations. Structurally, the multichannel porous carbon nanofibers with open ends could effectively enlarge the exposure of active sites, facilitate mass diffusion/charge transfer, and accelerate H2 release, leading to promoted reaction kinetics. Consequently, the optimized Mo@NMCNFs exhibited superior Pt-like HER performance in 0.5 M H2SO4 electrolyte with an overpotential of 66 mV at 10 mA cm-2, a Tafel slope of 48.9 mV dec-1, and excellent stability, outperforming a vast majority of the previously reported nonprecious HER electrocatalysts. The concept of both geometric and electronic engineering of SACs in this work may provide guidance for the design of high-efficiency molecule-like heterogeneous catalysts for a myriad of energy technologies.

Lithium metal is considered as a strongly attractive anode candidate for the high-energy-storage field, but its dreadful dendrite growth has haunted its commercialization progress. Herein, we develop a lithiophilic Nb2O5-embedded three-dimensional (3D) carbon nanofiber network (Nb2O5-CNF) as a scaffold to preload molten Li for the fabrication of dendrite-free composite anode. The in situ lithiation reaction between molten Li and Nb2O5 nanocrystals results in the formation of nanosize LixNbyO nanoparticles, which can serve as preferred sites that regulate nucleation/growth behavior of Li during the plating process. Besides, due to its high structural stability and abundant internal inner space, the 3D CNF network can function as a reservoir to confine the dimensional expansion of "hostless Li". The resulting Li composite anodes exhibit enlarged active areas and reduced interfacial energy barriers, delivering a prolonged cycling of 1000 h with an ultralow hysteresis of 52 mV and dendrite-free morphology in a symmetric cell (1.0 mA cm-2). Coupled with the LiFePO4 cathode, the Li@Nb2O5-CNF anode sustains a reversible capacity of 163 mAh g-1 with an excellent capacity retention of 93.0% after 370 cycles at 0.5C. This all-around strategy of lithiophilic sites coupled with a 3D conductive nanofiber matrix may shed light on promising applications of high-capacity and dendrite-free Li-metal batteries.

Alloy catalysts often show superior effectiveness in the growth of carbon nanotubes/nanofibers (CNTs/CNFs) as compared to monometallic catalysts. However, due to the lack of an understanding of the...

9 figures, 5 tables.-- Supplementary information available, Active and durable electrocatalysts for the oxygen evolution reaction (OER), capable of replacing noble metal catalysts, are required to develop efficient and competitive devices within the frame of the water electrolysis technology for hydrogen production. In this work, we have investigated tantalum based catalysts supported on carbon nanofibers (CNF) for the first time. The effect of CNF characteristics and the catalyst annealing temperature on the electrochemical response for the OER have been analyzed in alkaline environment using a rotating ring disc electrode (RRDE). The best OER activity and oxygen efficiency were found with a highly graphitic CNF, despite its lower surface area, synthesized at 700 °C, and upon a catalyst annealing temperature of 800 °C. The ordering degree of carbon nanofibers favors the production of oxygen in combination with a low oxygen content in tantalum oxides. The most active catalyst exhibited also an excellent durability., The authors want to thank the Ministerio de Economía, Industria y Competitividad (MICINN) and FEDER for the received funding in the project of reference ENE2017-83976-C2-1-R, and to the Gobierno de Aragón (DGA) for the funding to Grupo de Investigación Conversión de Combustibles (T06_17R). J.C. Ruiz-Cornejo acknowledges DGA for his PhD grant. D. Sebastián acknowledges the MICINN for the Ramón y Cajal research contract (RyC-2016-20944).

Developing high-efficient bifunctional electrocatalysts is significant for the overall water splitting. Bimetallic phosphides show great potential for the bifunctional hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) catalysts due to the excellent catalytic performance. Herein, the CoFeP two-dimensional nanoarrays successfully grown on nitrogen doped electrospun carbon nanofibers (CoFeP NS@NCNF) through template-directed growth and following phosphorization treatment. Benefiting from the hierarchical nanoarrays structure, synergistic effect of high electrical conductivity carbon nanofiber substrate and bimetallic phosphide, the CoFeP NS@NCNF exhibits efficient bifunctional electrocatalytic activities for OER and HER in 1 M KOH with overpotentials of 268 mV (η20) and 113 mV (η10), respectively. Moreover, the CoFeP NS@NCNF coupled two-electrode system needs a low voltage of 1.59 V at 10 mA cm−2 for overall water splitting. This work provides a promising way for the preparation of transition metal-based electrocatalysts with hierarchical structure derived from Prussian blue analogues (PBAs) for OER and HER.

Design of highly active and stable non-precious electrocatalysts towards hydrogen evolution reaction (HER) is a hot research topic in low cost, clean and sustainable hydrogen energy field, yet remaining the important challenge caused by the sluggish reaction kinetics for water-alkali electrolyzers. Herein, a robust electrocatalyst is proposed by designing a novel sub-nanometer of copper and ruthenium bimetallic phosphide nanoclusters (RuxCuyP2) supported on a graphited carbon nanofibers (CNF). Uniform RuxCuyP2 (~1.90 nm) on the surface of CNF are obtained by introducing the dispersed Ru, thereby improving the intrinsic activity for HER. On optimizing the Ru ratio, the (x = y = 1) RuCuP2/CNF catalyst exhibits an excellent HER electroactivity with an overpotential of 10 mV in 1.0 M NaOH electrolyte to produce 10 mA cm−2 current density, which is lower than commercial 20% Pt/C in alkaline solution. Moreover, the kinetic study demonstrated that electrochemical activation energies for HER of RuCuP2/CNF is 20.7 kJ mol−1 highest among different ratio bimetallic phosphide. This simple, cost-effective, and environmentally friendly methodology can pave the way for exploitation of bimetallic phosphide nanoclusters for catalyst design.

Potassium-selenium (K-Se) batteries have attracted more and more attention because of their high theoretical specific capacity and natural abundance of K resources. However, dissolution of polyselenides, large volume expansion during cycling and low utilization of Se remain great challenges, leading to poor rate capability and cycle life. Herein, N/O dual-doped carbon nanofibers with interconnected micro/mesopores (MMCFs) are designed as hosts to manipulate Se molecular configuration for advanced flexible K-Se batteries. The micropores play a role in confining small Se molecule (Se2–3), which could inhibit the formation of polyselenides and work as physical barrier to stabilize the cycle performance. While the mesopores can confine long-chain Se (Se4–7), promising sufficient Se loading and contributing to higher discharge voltage of the whole Se@MMCFs composite. The N/O co-doping and the 3D interpenetrating nanostructure improve electrical conductivity and keep the structure integrity after cycling. The obtained Se2–3/Se4–7@MMCFs electrode exhibits an unprecedented cycle life (395 mA h g−1 at 1 A g−1 after 2000 cycles) and high specific energy density (400 Wh kg−1, nearly twice the specific energy density of the Se2–3@MMCFs). This study offers a rational design for the realization of a high energy density and long cycle life chalcogen cathode for energy storage.

Recent development in desalination technology can be progressed in terms of fabricated nanomaterials and operating parameters, as one among energy-storing systems including fuel cells, capacitors, batteries, and so on. Regarding the examined nanomaterials, embedded CoCr7C3 nanoparticles onto carbon nanofibers (CoCr7C3@CNFs) were prepared using a facile electrospinning technique. Characterization techniques, such as XRD, FESEM, TEM, HRTEM, STEM, and EDX, were served to define the crystallinity, morphology and chemical composition of the synthesized nanofibers. XRD chart demonstrated the formation of Cr7C3 species along with deposited metallic cobalt in this nanomaterial. The morphological study revealed the uniform distribution of metallic cobalt and Cr7C3 nanoparticles onto the fibrous CNFs structure. The electrochemical performance of CoCr7C3@CNFs was studied in 1.0 M NaCl solution at 5 mV s−1 to record a specific capacitance of 250 F g−1. Electrochemical impedance spectroscopy measurements indicated better electron transfer properties after introducing CoCr7C3 to the CNFs structure. Furthermore, its outstanding electrosorption capacity of 20.40 mg g−1 might encourage the preparation of additional nanocomposites for future capacitive deionization (CDI) technology.

In this study, we applied iron (-oxide) incorporated carbide nanofiber composites as heterogeneous catalysts with wide visible-light absorption ability, catalytic reactivity, and catalytic stability for the highly efficient decomposition performance. Notably, water vapor activated iron (-oxide) incorporated carbide nanofiber catalyst (Act-Fe-CNF) showed high crystalline Fe3O4 phase, saturation magnetization point (17.76 emu/g), and large surface area (508.2 m2/g). In water vapor activation, Fe3C particles inside carbide nanofiber oxidized and aggregated to larger Fe3O4 particles, thereby forming a meso/macroporous structure and improving surface area offering more available active sites for catalytic reactivity. Under both UV-/real solar-light irradiation, it was demonstrated that the Act-Fe-CNF catalysts exhibited unprecedentedly excellent removal capabilities (>98%, [k] = 4.06 h−1) for rhodamine B, leading to complete water purification. Interestingly, the AF-CNFs catalysts also showed strong antimicrobial activities against gram-negative Escherichia coli (E. coli) and gram-positive Staphylococcus aureus (S. aureus) under incandescent-light irradiation. These results indicated that the Act-Fe-CNF catalysts might have utility in important environmental and bio-medical applications.

A novel electrocatalyst has been developed based on polypyrol-carbon nanofiber (PPy-CNF) support material to increase the stability of Pt/ PPy-CNF/GDL electrocatalyst in direct methanol fuel cell (DMFC). A novel conducting polymer (PPy)-CNF nanocomposites was prepared by a solution dispersion technique and used to support platinum nanoparticles. For preparation of catalyst ink, 20 wt.% Pt/PPy-CNF electrocatalyst with a platinum loading of 0.4 mg cm-2 was prepared by ethylene glycol (EG) method. Physical and electrochemical properties were analyzed by X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) imaging and cyclic voltammetry (CV) experiments. FTIR results prove the existence of PPy in the support. SEM images showed that the one–dimensional CNFs were efficaciously covered by PPy. The TEM characterization revealed that the fine Pt nanoparticles prepared by polyol method were dispersed on the surface of the electrocatalyst successfully. XRD patterns also revealed that the mean size of Pt crystal nanoparticles was about 3.69, 6.51 and 2.91 nm for Pt/PPy-CNF, Pt/CNF and Pt/C electrocatalyst respectively. The size of the PPy on carbon paper has been measured in the range of 35-40nm by AFM. Based on the electrochemical properties and acceleration tests evaluated by cyclic voltammetry measurements and Chronoamperometric experiments it was found that the as prepared Pt/PPy-CNF/GDL electrode exhibited a comparable electrochemical surface are (ECSA), MOR activity and so stability (in the presence of methanol) with respect to the Pt/CNF /GDL and Pt/C/GDL commercial one. A rather significant reduction in the peak potential of methanol electro-oxidation from 0.69V for Pt/C/GDL to 0.76V for Pt/PPy-CNF/GDL electrode indicates that an increase in the activity for MOR is achieved by replacing the C by PPy-CNF. The corresponding ECSA values for the Pt/PPy-CNF/GDL, Pt/CNF/GDL and Pt/C/GDL electrodes were 108.69, 53.93 and 17.98 m2g-1 respectively.

The ever-increasing concern for adverse climate changes has propelled worldwide research on the reduction of CO2 emission. In this regard, CO2 electroreduction (CER) to formate is one of the promising approaches to converting CO2 to a useful product. However, to achieve a high production rate of formate, the existing catalysts for CER fall short of expectation in maintaining the high formate selectivity and activity over a wide potential window. Through this study, we report that Bi2O3 nanosheets (NSs) grown on carbon nanofiber (CNF) with inherent hydrophobicity achieve a peak formate current density of 102.1 mA cm-2 and high formate Faradaic efficiency of >93% over a very wide potential window of 1000 mV. To the best of our knowledge, this outperforms all the relevant achievements reported so far. In addition, the Bi2O3 NSs on CNF demonstrate a good antiflooding capability when operating in a flow cell system and can deliver a current density of 300 mA cm-2. Molecular dynamics simulations indicate that the hydrophobic carbon surface can repel water molecules to form a robust solid-liquid-gas triple-phase boundary and a concentrated CO2 layer; both can boost CER activity with the local high concentration of CO2 and through inhibiting the hydrogen evolution reaction (HER) by reducing proton contacts. This water-repelling effect also increases the local pH at the catalyst surface, thus inhibiting HER further. More significantly, the concept and methodology of this hydrophobic engineering could be broadly applicable to other formate-producing materials from CER.

Electricity has been generated from evaporation-driven water flow in films of carbon soot particles and other porous media. This paper reports the placement of carbon nanofiber mats (CNMs) on fiberglass screens for the construction of efficient water-evaporation-induced generators (WEIGs). These CNMs are prepared from carbonizing electrospun polyacrylonitrile nanofiber mats and then treating them with oxygen plasma. After electrode attachment to the two ends of a CNM, one electrode is immersed into water. Water rises in the mat due to capillary action and evaporates from the mat surface due to thermal energy provided by the environment. The steady rise of water pushes the dissociated ions of the surface functionalities upward, resulting in a streaming current and an electric potential. This paper investigates how the generated short-circuit current, Is, and open-circuit voltage, Vo, of the WEIG change with structural parameters of the CNMs. Under optimized conditions, these CNMs produce electricity at an areal power density of 83 nW/cm2, which is almost 10 times those offered by some existing ones. Thus, the easy-to-handle CNMs are an attractive porous scaffold for WEIGs.

Sodium (Na) metal is considered a promising anode material for high-energy Na batteries due to its high theoretical capacity and abundant resources. However, uncontrollable dendrite growth during the repeated Na plating/stripping process leads to the issues of low Coulombic efficiency and short circuits, impeding the practical applications of Na metal anodes. Herein, we propose a silver-modified carbon nanofiber (CNF@Ag) host with asymmetric sodiophilic features to effectively improve the deposition behavior of Na metal. Both density functional theory (DFT) calculations and experiment results demonstrate that Na metal can preferentially nucleate on the sodiophilic surface with Ag nanoparticles and uniformly deposit on the whole CNF@Ag host with a "bottom-up growth" mode, thus preventing unsafe dendrite growth at the anode/separator interface. The optimized CNF@Ag framework exhibits an excellent average Coulombic efficiency of 99.9% for 500 cycles during Na plating/stripping at 1 mA cm-2 for 1 mAh cm-2. Moreover, the CNF@Ag-Na symmetric cell displays stable cycling for 500 h with a low voltage hysteresis at 2 mA cm-2. The CNF@Ag-Na//Na3V2(PO4)3 full cell also presents a high reversible specific capacity of 102.7 mAh g-1 for over 200 cycles at 1 C. Therefore, asymmetric sodiophilic engineering presents a facile and efficient approach for developing high-performance Na batteries with high safety and stable cycling performance.

As an excellent microwave absorption material, the in-depth study of carbon-based nanofibers’ absorbing mechanism is of great significance for subsequent applications. In this paper, carbon/SiO2 core-sheath nanofibers with Co-Fe nanoparticles embedded in were synthesized by electrospinning and carbonization. The morphology, microstructure, magnetic properties, and microwave absorption performance of the composite nanofibers were characterized in detail. The results show that the maximum reflection loss (RL) could reach to −59.6 dB, and the maximum effective absorption bandwidth (RL