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Herein, we present a freestanding and flexible 3D nanocomposite made of polyhedral spherical FeCoS2 and nitrogen-doped hollow carbon nanofibers (FeCoS2@N-HCNFs) that is synthesized through coaxial electrospinning, high-temperature calcination, and a facile solvothermal process. As a binder-free anode composite for potassium-ion batteries (PIBs), FeCoS2@N-HCNF presents a high specific discharge capacity on the first lap (701.2 mA h g−1 at 100 mA g−1) and superior cycling stability (132.6 mA h g−1 at 3200 mA g−1 after 600 cycles). The impressive electrochemical performance can be ascribed to the unique 3D structure, such as the enormous specific surface area of the mesoporous structure beneficial for K+ transfer, the three-dimensional hollow carbon nanofiber scaffold enhances the structural stability, and polyhedral spherical FeCoS2 improves the overall specific capacity. According to the above description, the FeCoS2@N-HCNF anode is a promising candidate for advanced potassium-ion batteries. [ABSTRACT FROM AUTHOR]

Abstract A freestanding γ-Fe 2 O 3 /carbon nanofiber composite as the anode of lithium ion batteries has been prepared with γ-Fe 2 O 3 nanoparticles aligned in the tubular channels of the nanofibrous carbon matrix. Innovatively, a large amount of voids are generated for confining a very high active mass content by facilely verifying the ratio of carbon source and the sacrificing pore-forming agent, poly(methyl methacrylate). The best electrochemical performance at an active mass ratio of 70% is obtained with a high discharge capacity of 1088 mAh g−1 retained after 300 cycles at 0.2 C. Good rate capability and long life-span performance are further achieved at 0.5 and 2 C for 600 and 1000 cycles, respectively. In situ X-ray patterns further reveal better exploitation of the active materials for this γ-Fe 2 O 3 /carbon nanofiber composite electrode. The enhanced electrochemical performance of lithium ion batteries can be ascribed to the well-dispersed γ-Fe 2 O 3 nanoparticles within the porous carbon matrix, as well as the cross-linked fiber morphology. Consequently, this study provides a superior electrode architecture for constructing flexible anodes of high-performance lithium ion batteries. Graphical abstract The freestanding γ-Fe 2 O 3 /carbon nanofiber composite with hierarchical porous structure promotes the development of long life-span lithium ion batteries. Image 1 [ABSTRACT FROM AUTHOR]

A hierarchically porous carbon nanofiber (HPCNF) material was prepared by a facile electrospinning method, with polyvinylpyrrolidone (PVP) as the carbon source and silica formed in-situ as the template. The carbon nanofibers showed a well-designed pore structure: centered macropores are surrounded by a denser cycle consisting of micro-/mesopores near the surface. Sulfur was encapsulated into the pores by solution penetration, followed by a melt diffusion method to generate a flexible sulfur/HPCNF (S/HPCNF) cloth as the binder-free cathode in lithium sulfur (Li-S) batteries. The HPCNF carbon with multi-scaled pores acts as an efficient host for large amounts of sulfur, and accommodates the associated volume expansion during electrochemical cycling. Moreover, the hierarchical architecture significantly reduces the escape of polysulfides during the cycling. The unique material allowed sulfur loading of 2.2–12.1 mg cm −2 , and exhibited a high sulfur utilization of more than 80% with high areal capacity of 11.3 mAh cm −2 , demonstrating that S/HPCNF is a promising cathode material for Li-S batteries of high energy density. [ABSTRACT FROM AUTHOR]

In this work, we have developed a new cost-effective counter-electrode based on the Bi 2 S 3 /carbon nanofibers (Bi 2 S 3 /CNFs), which synthesized by combining the advantages of electrospinning technology and hydrothermal method. And by adjusting the concentration of Bi 2 S 3 , the Bi 2 S 3 nanoparticles were densely grown on the surface of carbon nanofibers without agglomeration. The dye-sensitized solar cells fabricated using Bi 2 S 3 /CNFs nanocomposite as counter electrode exhibit an overall power conversion efficiency of 7.64 % measured at 100 mWcm–2 illumination (AM 1.5 G), which is significantly higher than that of the most commonly used but expensive Pt counterpart (7.12 %). • Electrospun and hydrothermal techniques were used to synthesize the Bi 2 S 3 /carbon nanofibers (Bi 2 S 3 /CNFs). • A novel composite of Bi 2 S 3 /CNFs was first synthesized and used as counter electrode for DSSCs. • The DSSCs based on Bi 2 S 3 /CNFs CE achieved a PCE of 7.64%, which is significantly higher than Pt CE (7.12%). Dye-sensitized solar cells (DSSCs) counter electrode (CE) is needed to have both good electrical conductivity and high catalytic activity, and composite materials are better meet these two requirements. In this work, Bi 2 S 3 /carbon nanofiber (CNFs) composites are synthesized by simple electrospinning and hydrothermal methods, and after optimization of the content of Bi 2 S 3 , the large amount Bi 2 S 3 nanoparticles are grown densely on CNFs without agglomeration. Bi 2 S 3 /CNFs composites are first introduced into DSSCs as CE. The optimized Bi 2 S 3 /CNFs composites are of great electrochemical performance and obtain a photoelectric conversion efficiency (PCE) of 7.64 %, which is better than common used Pt CE (7.12 %). Thus Bi 2 S 3 /CNFs CE has great prospects based on low cost and simple fabrication process to develop Pt-free CEs which could accelerate the large-scale application of DSSCs. [ABSTRACT FROM AUTHOR]

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

Rhenium-doped platinum-nickel nanostructures supported on carbon nanofibers (Re-Pt 3 Ni/CN) were fabricated, used as counter electrodes (CEs) in dye-sensitized solar cells (DSSCs), by a simple electrospinning technique and a hydrothermal method. DSSCs employing Re-Pt 3 Ni/CN electrodes showed a higher power conversion efficiency (PCE) of 9.36% compared to solar cells with Pt, CN and Pt 3 Ni/CN CEs measured under the same conditions. The excellent photoelectric performance of the Re-Pt 3 Ni/CN CE is attributed to its stable octahedral structure and large specific surface area. Accordingly, the Re-Pt 3 Ni/CN CE is a promising cost-effective alternative CE for DSSCs. [ABSTRACT FROM AUTHOR]

Molybdenum sulfide/carbon nanofibers (MoS 2 /CNFs) composite with high density of flower-like nanosheets are prepared via the combination of electrospinning technology and hydrothermal method. The MoS 2 /CNFs composite exhibits good performance as a counter electrode (CE) in dye-sensitized solar cells (DSSCs). The DSSCs employing MoS 2 /CNFs delivers a power conversion efficiency (PCE) of 8.46%, which is higher than that of the devices with CNFs CE (6.59%) and platinum CE (7.65%) under the same conditions. Thus, the excellent stability and facile preparation of the MoS 2 /CNFs electrode provide precondition for DSSCs application, while greatly enhancing the electrocatalytic activities of the DSSCs. [ABSTRACT FROM AUTHOR]

[Display omitted] • A three-dimensional hierarchical catalyst (Co/CoFe NAs@NCNFs) was fabricated. • Co/CoFe NAs@NCNFs exhibited excellent catalytic activity for ORR, OER and HER. • The catalyst was used as a cathode catalyst for MFC and to drive water splitting. • The peak power density of the MFC can reach 2139.6 ± 43 mW m−2. Herein, a novel MOF-derived trifunctional electrocatalyst with a three-dimensional hierarchical structure of N -doped carbon nanofibers (NCNFs) compounded with vertically grown nanosheets loaded with Co and CoFe alloy nanoparticles is reported. It is found that Co/CoFe NAs@NCNFs has a good half-wave potential of 0.83 V for ORR, the overpotential of 290 mV and 103 mV for OER and HER, respectively. When Co/CoFe NAs@NCNFs catalyst is employed on the cathode of a microbial fuel cell (MFC), the peak power density of the MFC can reach 2139.6 ± 43 mW m−2, which is 1.56 times better than that of commercial Pt/C. Furthermore, the assembled MFCs can also successfully drive the water splitting. The above excellent performance is mainly due to the structure of the interwoven NCNF networks combined with nanosheets which greatly enhances the surface area and mass transfer capacity of the material, and the loaded nanoparticles are constructed into a large number of Fe-N x -C and Co-N x -C active sites, further increasing the catalytic performance of Co/CoFe NAs@NCNFs. This work could provide a novel approach to the regeneration and conversion of clean energy. [ABSTRACT FROM AUTHOR]

A new type of ZnFe 2 O 4 /CNFs composite has been synthesized by a two-step process of electrospinning and hydrothermal method and further applied as counter electrode on Ti mesh substruct in the dye-sensitized solar cells, which can deliver an overall power conversion efficiency of 9.05% at 100 mW·cm−2 illumination (AM 1.5G). Compare with traditional FTO glass, Ti mesh exhibits higher performance, which lead to the power conversion efficiency of CNFs is much higher than Pt counter electrode. • ZnFe 2 O 4 /CNFs composite was successfully prepared by electrospinning and hydrothermal methods. • Low-cost Ti mesh was used as counter electrode substrate in DSSCs instead of FTO glass. • ZnFe 2 O 4 /CNFs Ti mesh CEs showed excellent electrocatalytic activity and stability. • The ZnFe 2 O 4 /CNFs counter electrode yielded a higher PCE (9.05%) than Pt CE (7.21%). There is no doubt that counter electrode (CE) plays a vital role in dye-sensitized solar cells (DSSCs). Herein, Zinc Ferrite/carbon nanofibers (ZnFe 2 O 4 /CNFs) composite is successfully fabricated by electrospinning and hydrothermal method and coated on titanium (Ti) mesh as an efficient CE material, which is further applied to DSSCs. The Ti mesh has been done as conductive substrate to make the DSSCs have smaller transmission resistance, great stability and sustainable utilization. Via repeated measurements, the ZnFe 2 O 4 /CNFs CE which is prepared on Ti mesh exhibits good power conversion efficiency (PCE) of 9.05%, which is higher than commercial Platinum (Pt) fluorine-doped tin oxide (FTO) CE (7.21%) and CNFs Ti mesh CE (7.80%) under the same conditions. Most interestingly, the CNFs CE that prepared on Ti mesh has higher PCE than Pt CE, this is mainly due to the use of Ti mesh which is more conducive to the interface transport of iodine ion and electron transfer rate. All of these results indicate that ZnFe 2 O 4 /CNFs composite Ti mesh CE has high electrochemical performance and can be favorable for low-cost efficient DSSCs application. [ABSTRACT FROM AUTHOR]