Owing to the excellent redox reversibility and structural diversity, polytriphenylamine (PTPAn) has been regarded as one of the promising cathode candidates for sodium-ion batteries. However, it ...still suffers from the bulk aggregation and low operating capacity in practical applications. Assisted by the
in-situ
polymerization, leaf-like PTPAn nanosheets are uniformly introduced on the surface of carbon nanofibers (CNFs) to form the free-standing CNF@PTPAn composite electrodes. Interestingly, the formation mechanism of the leaf-on-branch structure of CNF@PTPAn composites is systematically explored, confirming that the controlling of oxidation rate and growth degree plays crucial roles in tuning the morphology and active material content of the composite electrodes. Supported by the capacity-cutting analysis, the effective coupling between the active PTPAn and conductive CNFs can provide fast electron/ion-shuttling channels and deepen the electrochemical reaction process. At 50 mA g
−1
, the capacity of the optimized CNF@PTPAn composite can reach 105 mA h g
−1
, with a stable rate capability of 78 mA h g
−1
even at 400 mA g
−1
after 500 cycles in a half cell. The detailed kinetic analysis confirms that the ion-storage behaviors in the low-voltage region can be tailored for the improved capacitive contribution and diffusion coefficients. Meanwhile, the flexible CNF-based full cell with CNF@PTPAn as the cathode and CNFs as the anode exhibits a high energy density of 60 W h kg
−1
at 938 W kg
−1
. Based on this, the rational design is expected to provide more possibilities to obtain advanced freestanding electrode systems.
High modulus and conductivity tantalum carbide-carbon nanofibers with excellent thermal stability were fabricated by electrospinning followed with carbothermal reduction.
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•Tantalum ...carbide-carbon (TaC/CNF) electrospun nanofibers.•Single TaC/CNF possess high modulus (450GPa).•TaC/CNF membrane has high electric conductivity (25S/cm).•Mechanical flexibility with 200 bending cycles.•Conductivity remains 90% and 55% after 80 and 180 bending cycles, respectively.
Tantalum carbide has been widely used as an excellent refractory material. However, there are no reports regarding the continuous tantalum carbide-carbon nanofibers (TaC/CNFs) and their mechanical and electrical properties. In this work, TaC/CNFs were prepared by electrospinning. The morphology and structures of the nanofibers and the distribution of TaC in the nanofibers were investigated by SEM, EDX, TEM, XRD, XPS and Raman spectroscopy. The TaC/CNFs showed excellent thermal stability, mechanical flexibility and conductivity even after folding for 180 cycles. These flexible, refractory and conductive TaC/CNFs could be found potential applications for flexible electronic devices and refractory materials.
The photocatalytic generation of hydrogen peroxide (H2O2) from H2O and O2 under visible light irradiation is a hopeful approach to achieve solar-to-chemical energy transformation. While the lack of ...specific redox reaction centers is still the main reason for low photocatalytic H2O2 production efficiency, herein, we present a conjugated organic polymer (AQTEE-COP) containing anthraquinone redox centers by Sonogashira cross-coupling reaction between 2,6-dibromoanthraquinone (AQ) and 1,1,2,2-tetrakis(4-ethynylphenyl)ethene. The extended π-conjugated framework with an electron push–pull effect between electron-donating tetraphenylethene moieties and electron-withdrawing anthraquinone moieties not only broadened the visible light absorption range but also promoted the separation and migration of photo-induced charge carriers. Meanwhile, the anthraquinone moieties can serve as redox centers to accept photo-induced electrons and transfer them to adsorbed O2 molecules for subsequent H2O2 production. The well-defined structure of AQTEE-COP with task-specific anthracene redox centers provides molecular-level insights into the mechanistic understanding of the photocatalytic H2O2 generation from H2O and O2. The AQTEE-COP exhibits efficient photocatalytic H2O2 production with an initial rate of 3204 μmol g–1 h–1 under visible light (λ ≥ 400 nm) irradiation without any additional photosensitizers, organic scavengers, or co-catalysts. This article provides a protocol for the rational design of pre-functionalized conjugated organic polymer-based materials for solar-to-chemical energy transformation.
In this paper, a simple and highly selective electrochemical method for the simultaneous determination of catechol (CC) and hydroquinone (HQ) has been developed with a three-dimensional (3D) N-doped ...carbon nanotube (NCNT) film electrode. The 3D NCNT film was prepared by the combination of electrospinning and chemical vapor deposition procedure; dense and uniform NCNTs were firmly bonded onto the electrospun carbon nanofiber matrix (NCNT@CNFs). By directly dropping the flexible film onto the electrode surface without additional oxidant treatment, a dihydroxybenzene biosensor can be easily constructed. Differential pulse voltammetry (DPV) results showed that the isomers can be detected selectively at NCNT@CNF modified electrode with peak-to-peak separation about 115mV. Under the optimized condition, the sensing platform showed wide linear responses from 0.08 to 350μM and 0.1–425μM with detection limits of 20nM and 50nM (S/N=3) for CC and HQ, respectively. The proposed method was successfully applied to the simultaneous determination of CC and HQ in real samples with reliable recovery. The N-doping combining with abundant defective sites and favorable 3D network structure facilitate the electron transfer, which resulted in excellent electrocatalytic performance. The attractive electrochemical performances and facile preparation method made this novel electrode promising for the development of effective dihydroxybenzene sensor.
Lithium–sulfur (Li–S) batteries have attracted great attention because of their high energy density and high theoretical capacity. However, the “shuttle effect” caused by the dissolution of ...polysulfides in liquid electrolytes severely hinders their practical applications. Herein, we originally propose a carboxyl functional polyamide acid (PAA) nanofiber separator with dual functions for inhibiting polysulfide transfer and promoting Li+ migration via a one-step electrospinning synthesis method. Especially, the functional groups of −COOH in PAA separators provide an electronegative environment, which promotes the transport of Li+ but suppresses the migration of negative polysulfide anions. Therefore, the PAA nanofiber separator can act as an efficient electrostatic shield to restrict the polysulfide on the cathode side, while efficiently promoting Li+ transfer across the separator. As a result, an ultralow decay rate of only 0.12% per cycle is achieved for the PAA nanofiber separator after 200 cycles at 0.2 C, which is less than half that (0.26% per cycle) of the commercial Celgard separator.
•Photocatalytic hydrogen peroxide production from water and oxygen under visible light irradiation without any additives.•The phenanthrenequinone moieties in PQTEE-COP serve as redox centers can ...avoid the use of co-catalysts.•The extended π-conjugated framework with electron push–pull dyads not only improve visible light harvesting, but also accelerate photo-induced charges separation and migration.•The PQTEE-COP exhibits efficient photocatalytic H2O2 production with initial rate of 3009 μmol g-1h−1, which much higher than that of reported polymer-based photocatalysts.
Photocatalytic preparation of hydrogen peroxide (H2O2) by visible light irradiation is a promising approach to achieve the conversion of solar-to-chemical energy. But it still faces a huge challenge with the development of efficient and environmentally friendly catalytic system which is applied to H2O2 production from H2O and O2 without any additives. Hereby, we present a conjugated organic polymer (PQTEE-COP) by Sonogashira cross-coupling reaction between 2,7-dibromophenanthrenequinone (PQ) with 1,1,2,2-tetrakis(4-ethynylphenyl)ethene (TEE), which contains phenanthrenequinone redox centers and can efficient photocatalysis the production of H2O2 from H2O and O2 without any additives. The extended two-dimensional π-conjugated framework with electron-donor tetrakis(4-ethynylphenyl)ethene and electron-acceptor phenanthrenequinone moieties can not only improve visible light harvesting, but also accelerate photo-induced charges separation and migration. In addition, the phenanthrenequinone moieties can serve as redox centers to accept photo-induced electrons and transfer to adsorbed O2 molecule for subsequent H2O2 production through electron-coupled hydrogenation reaction (PQ to PQH2). The PQTEE-COP exhibits efficient photocatalytic production of H2O2 with initial rate of 3009 μmol g-1h−1 from H2O and O2 under visible light (λ ≥ 400 nm) irradiation without any additives. This work provides a scheme for the rational design of conjugated organic polymer based materials for efficient solar-to-chemical energy conversion.
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•Bio-inspired by wood’s microchannels, a PTCDA/NC/CNT cathode with mechanical deformability is designed.•Due to the strong capillarity, the organic cathode exhibits rather low ...impedance and ultrafast Na+ diffusion kinetics.•The flexible all-organic sodium-ion full battery delivers ultrahigh energy density and power density.
As one of the typical organic cathode materials for sodium ion batteries (SIBs), 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) is formidably challenged in practical applications because of its low electrical conductivity, sluggish reaction kinetics, inferior rate capability and cycle life. Inspired by the ultra-strong capillarity of wood’s aligned hierarchical microchannels toward ions and water during metabolism, we have designed a novel composite nanofibrous organic cathode consisting of PTCDA/nitrogen-doped carbon/carbon nanotubes (PTCDA/NC/CNT) for SIBs. The PTCDA/NC/CNT cathode exhibits rapid ionic/electronic transport properties and ultrafast reaction kinetics owing to the synergistic effects of the interconnected conductive frameworks and ultra-strong capillarity derivingfrom the hierarchical micro/nanotunnels. As a result, a highly reversible capacity of 135.6 mA h g−1 at 50 mA g−1, excellent rate performance and ultra-long cyclic stability with over 95% capacity retention after 500 cycles at 1000 mA g−1 are achieved for the PTCDA/NC/CNT cathode in SIBs. Remarkably, an all-organic battery using the PTCDA/NC/CNT cathode and conjugated sodium carboxylate/CNT anode also delivers a high energy density of 85 W h kg−1 at a power density of 665 W kg−1. This bio-inspired design provides a promising strategy for the development of next-generation all-organic sodium-ion full batteries.
Nanostructured nickel-cobalt binary hydroxide (NiCoBH) is widely investigated as supercapacitor electrode material. However, the aggregation and poor electrical conductivity of NiCoBH limit its ...practical application as a supercapacitor. In this work, a flexible free-standing hierarchical porous composite composed of NiCoBH nanosheets and titanium carbide-carbon nanofiber (NiCoBH@TiC/CNF) is fabricated through electrospinning and microwave assisted method. The as-prepared composites exhibit desirable electrochemical performances, including high specific capacitance, cycling stability, and rate capability. In particular, the NiCoBH41@TiC/CNF composite electrode exhibits a maximum specific capacitance of 2224 F g−1 at the current density of 0.5 A g−1 and excellent cyclic stability of 91% capacity retention after 3000 cycles at 5.0 A g−1. To expand its practical application, an asymmetric supercapacitor (ASC) is fabricated using the NiCoBH41@TiC/CNF composite as the positive electrode and active carbon as the negative electrode. The ASC exhibits a prominent energy density of 55.93 Wh kg−1 and a high power density of 18,300 W kg−1 at 5.0 A g−1. The superior electrochemical property is attributed to the uniform dispersion of NiCoBH nanosheets on the TiC/CNF felt matrix. The TiC/CNF felt with uniformed TiC nanoparticles makes the fiber surface more suitable for growing NiCoBH nanosheets and simultaneously enhances the conductivity of electrode.
The high-performance ASC is fabricated based on flexible TiC/CNF felt that supports interwoven nickel-cobalt binary hydroxide nanosheets. Display omitted
•Flexible & conductive TiC/CNF is a beneficial matrix in NiCoBH@TiC/CNF composite.•Numerous NiCoBH nanosheets are uniformly coated on the rough surface of TiC/CNFs.•The composite electrode exhibits an excellent rate capability and cycle stability.•ASC based on NiCoBH41@TiC/CNF shows a prominent energy and power density.
Conjugated carbonyl compounds are considered as ideal substitutes for traditional inorganic electrodes in lithium/sodium ion batteries (LIBs/SIBs) due to their excellent redox reversibility and ...structural tunability. Here, a flexible sandwich‐structured 3,4,9,10‐perylenetetracarboxylic dianhydride (PTCDA)/reduced graphene oxide (RGO)/carbon nanotube (CNT) (PTCDA/RGO/CNT) composite film with bioinspired micro/nanofluidic ion transport channels and interconnected porous conductive frameworks is designed and obtained by vacuum‐filtration and heating methods for LIB/SIB applications. The PTCDA/RGO/CNT electrode with robust mechanical deformability exhibits high diffusion coefficients of Li+/Na+ and low Warburg coefficients. Thus, desirable electrochemical performances with high capacities of 131 and 126 mA h g−1 at 10 mA g−1, and ultralong cycling stability with over 99% capacity retention after 500 cycles at 200 mA g−1 are achieved for LIBs and SIBs, respectively. In particular, Li/Na‐ion full cells consisting of lithiated or sodiated electrospun carbon nanofiber anode and PTCDA/RGO/CNT‐based cathode are developed to exhibit high energy densities of 132.6 and 104.4 W h kg−1 at the power densities of 340 and 288 W kg−1 for LIBs and SIBs, respectively. The advantageous features demonstrated by constructing bioinspired micro/nanofluidic channels may provide a new pathway toward the design of next‐generation wearable energy storage devices.
Inspired by the fast permeation of ions within the protein ion channels on cell membranes, a flexible sandwich‐structured 3,4,9,10‐perylenetetracarboxylic dianhydride (PTCDA)/reduced graphene oxide (RGO)/carbon nanotube (CNT) (PTCDA/RGO/CNT) film with bioinspired three‐dimensional multilayered micro/nanochannels is designed for lithium and sodium ion batteries. Because of the unique structural features, the PTCDA/RGO/CNT electrode exhibits particularly excellent lithium/sodium storage performance and cyclic stability.
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