Search

Owing to the clean and environment friendly advantages, electrochemical water splitting stands out among various hydrogen production strategies. Electrocatalysts play an important role in the hydrogen evolution reaction (HER). Hence, Pt-(Ni0.5Co0.5)2P/S-carbon fibers as electrocatalysts for highly efficient HER were prepared through the structural designing of CNF and heteroatom doping (sulfur (S) or boron (B)). First, three composites of the (Ni0.5Co0.5)2P/carbon fiber ((Ni0.5Co0.5)2P/CNF), (Ni0.5Co0.5)2P/porous carbon fiber ((Ni0.5Co0.5)2P/PCNF), and (Ni0.5Co0.5)2P/hollow porous carbon fiber ((Ni0.5Co0.5)2P/HPCNF) were fabricated via a facile electrospinning with a solvothermal method. (Ni0.5Co0.5)2P/PCNFs showed the smallest overpotential at a current density of 10 mA cm−2 among the three structures. (Ni0.5Co0.5)2P nanosheets loaded on the porous CNF with a large active surface area may expose active sites and shorten the ion transport channel. To improve the catalytic performance of (Ni0.5Co0.5)2P/PCNF, Pt nanoparticles were anchored on (Ni0.5Co0.5)2P/heteroatom doped-PCNF by the chemical reduction method. Pt-(Ni0.5Co0.5)2P/S doped-PCNF exhibited a small overpotential of 64 mV for the HER with 74.9 mV dec−1 Tafel slope and a good stability, which was attributed to the conductive S-doped PCNF facilitating electron transport, accompanying the synergistic effect between the bimetallic phosphide and Pt nanoparticles, thus providing a facile method for an efficient HER electrocatalysis. [ABSTRACT FROM AUTHOR]

An Fe2P nanoparticle (Fe2P NP)-decorated carbon nanofiber (represented as Fe2P@CNF) composite was in situ prepared by electrospinning and subsequent high-temperature treatment. Benefitting from the synergy effect between Fe2P NPs and CNFs, as well as improved interface polarization and impedance matching, the Fe2P@CNF composite exhibits excellent microwave absorption performance relative to pure CNFs, in which the Fe2P@CNF composite with a fill loading of only 10 wt% possesses a minimum reflection loss (RL) of −49.2 dB at 3.0 mm and a maximum effective absorption bandwidth of 6.0 GHz at 2.2 mm. Therefore, this work provides a promising approach for the design and synthesis of an Fe2P@CNF composite with high-performance microwave absorption. [ABSTRACT FROM AUTHOR]

Nitrogen-doped carbon nanoribbons and nanotubes decorated with Co3O4 nanoparticles were prepared by a metal-catalyzed graphitization–nitridization and oxidization process, using triazole and melamine as a solid nitrogen/carbon co-source, and assessed as anodes of lithium ion batteries (LIBs). These composite anodes display perfect electrochemical performance, indicating their potential for application in LIBs. [ABSTRACT FROM AUTHOR]

Catalysts with high catalytic activity and low cost are extremely significant for hydrogen production by water cracking. In this work, through simple electrospinning and carbonization methods, Ru with excellent catalytic activity is dispersed onto Fe4C to form Ru–Fe4C nanoparticles loaded on N-doped carbon nanofibers (Ru–Fe4C/NCNF), so that Ru can expose more active sites and thus improve HER catalytic activity. Meanwhile, the addition of low-cost Fe can reduce the use of noble metal Ru, thereby reducing the catalyst cost. On the other hand, the prepared Ru–Fe4C/NCNF can be used as a self-supporting working electrode and shows good stability. The experimental results show that the prepared Ru–Fe4C/NCNF can drive a current density of 10 mA cm−2 with only 106 mV in 1 M KOH, and more importantly, only 254 mV can produce a current density of 100 mA cm−2. At the same time, it shows excellent stability after continuously working for 100 h at a current density of 100 mA cm−2. This work provides a new thought to synthesize economical catalysts with high catalytic activity. [ABSTRACT FROM AUTHOR]

The nitrate reduction reaction is emerging as having tremendous potential to mitigate nitrate pollution and simultaneously produce valuable ammonia. Here, we propose Co3O4 nanoparticles embedded in porous carbon nanofibers (Co3O4@CNF) as a high-efficiency catalyst to convert nitrate to ammonia, and it achieves a high faradaic efficiency of 92.7% and an extremely large NH3 yield of 23.4 mg h−1 mg−1cat, and also presents excellent electrochemical stability. Theoretical calculations reveal that the potential determining step (PDS) reaches as low as 0.28 eV. This work is expected to open a new avenue to rationally design robust noble-metal-free catalysts for the electrochemical synthesis of ammonia. [ABSTRACT FROM AUTHOR]

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]

Palladium nanoparticle (PdNP) supported organo-kaolinite was used as a solid catalyst for the reduction and electrochemical detection of 4-chloro-2-nitroaniline (CNA). During the catalytic reduction in the presence of NaBH4, the effects of some essential experimental parameters were scrutinized. The rate of the reaction increases when the CNA concentration is decreased, while an increase in NaBH4 and catalyst concentration favored the reaction. The presence of a small amount of ascorbic acid (AA), used as an eco-friendly reducing agent, significantly increases the rate of the reaction. This increase was the consequence of the direct generation of dihydrogen, which accelerates the reaction by favoring the homogenization of the reaction medium. Despite the fact that the signal of CNA on an electrode modified by the catalyst was poorly reproducible, reduction of the nitro group occurs at a more favourable potential and the oxidation of the product of this reaction was catalyzed by evolved hydrogen following water reduction onto PdNPs. This phenomenon was marked by an irreversible signal 40 times higher, compared to the signal recorded in the absence of the catalyst at the gold electrode. This property can be firstly exploited for the detection of CNA at trace levels in an aqueous medium and secondly for the selective detection of nitroaromatic compounds and their metabolites. [ABSTRACT FROM AUTHOR]

Lithium–sulfur batteries are regarded as the most promising electrochemical energy storage device as a result of their satisfactory high specific capacity and high energy density values. However, the inferior conversion efficiency of lithium polysulfides (LiPSs) in essence leads to fast capacity decay, especially at a large current density during the charge–discharge process. Herein, we have successfully demonstrated that the conversion efficiency of LiPSs was remarkably promoted by employing nickel nanoparticles incorporated with nitrogen-doped multi-channel carbon nanofibers (Ni-NMCCF) as a multifunctional modification layer of the separator. The high polarity of the nitrogen atoms and the Lewis acid characteristics of the nickel atoms collectively create strong anchoring activity towards LiPSs, therefore leading to the severe inhibition of the occurrence of the shuttle effect. The electrocatalytic activity of the nickel nanoparticles greatly accelerates the reversible conversion efficiency of LiPSs, ensuring high capacity retention during long-term cycling. Thanks to these advantages, Ni-NMCCF delivered a superb rate performance of 1020 mA h g−1 at 1C and maintained 671 mA h g−1 even after 500 cycles, which is equivalent to a capacity decay of only 0.07% per cycle. [ABSTRACT FROM AUTHOR]

A proper design and ingenious preparation of advanced nonnoble metal catalysts with high cost performance and durability for the oxygen reduction reaction (ORR) is in great demand and still full of great challenges. In this study, nickel–cobalt bimetallic nanoparticles uniformly embedded in nitrogen-doped carbon nanofibers (NiCo@NCNFs) were fabricated via a facile electrospinning technique, followed by a carbonization process. The Ni–Co nanoparticles are highly dispersed and uniformly embedded in highly conductive nitrogen-doped carbon fibers, providing a high specific surface area (640.8 m2 g−1), abundantly exposed active sites and easily accessible electronic channels, thus achieving high ORR performance. In particular, the optimized Ni0.5Co1@NCNF catalyst exhibits a high onset potential (Eonset = 0.90 V vs. RHE) and half-wave potential (E1/2 = 0.83 V vs. RHE) in an alkaline medium. Moreover, it possessed an extraordinary long-term stability and methanol tolerance in comparison to a commercial 20% Pt/C catalyst. This simple and cost-effective strategy provides a basis for the large-scale production of highly efficient catalysts that are used in numerous renewable energy systems. [ABSTRACT FROM AUTHOR]

Transition-metal phosphides have been identified as effective materials for improving electrocatalytic hydrogen evolution. In this study, Ni2P, Co2P, and NiCoP yolk–shell structures were embedded in N- and P-doped carbon nanofibers (NPNFs) by controlling the heat-treatment procedure of the fiber precursors. The hydrogen evolution reaction (HER) activity of the samples was tested. The formation process of phosphides introduced a large number of surface defects that act as active sites to improve H2 evolution. NPNF embedding composite NiCoP particles exhibited better performance compared with Ni2P–NPNFs and Co2P–NPNF samples in acidic conditions. In the case of a molar ratio Ni : Co : P of 1 : 1 : 1, NiCoP-decorated NPNFs revealed the best HER performance, which is ascribed to the loading of NiCoP composite particles, which greatly increased the specific surface area. NiCoP–NPNFs exhibited overpotentials of 183 and 280 mV at current densities of 1 mA cm−2 and 10 mA cm−2, respectively, with a Tafel slope of 94.5 mV dec−1. [ABSTRACT FROM AUTHOR]

Much attention has been paid to freestanding and flexible electrodes of Li-ion batteries (LIBs) in order to match the requirements of the future trend of flexible electronics. In this paper, Fe7S8/C flexible nanofibers with nano-buffered spaces are synthesized by an electrospinning and vulcanization process. The Fe7S8/C flexible nanofiber film with enough flexibility and high electrical conductivity can be directly punched into a flexible electrode slice without current collector, binder and conductive additives. Experimental results show that the Fe7S8/CNF2-700 flexible nanofibers delivers a high reversible specific capacity of 675 mA h g−1 after 400 cycles at a current density of 1 A g−1. Its excellent electrochemical performance is mainly attributed to the fact that the carbon nanofiber affords a conductive pathway and the nano-void between the Fe7S8 nanoparticles and carbon matrix provides sufficient buffer space for the volume expansion of Fe7S8 during charge and discharge cycles. Therefore, it is quite hopeful that this composite nanofiber will become a potential candidate as an anode material for next-generation flexible LIBs. [ABSTRACT FROM AUTHOR]

Angiogenesis plays a critical role within the human body, from the early stages of life (i.e., embryonic development) to life-threatening diseases (e.g., cancer, heart attack, stroke, wound healing). Many pharmaceutical companies have expended huge efforts on both stimulation and inhibition of angiogenesis. During the last decade, the nanotechnology revolution has made a great impact in medicine, and regulatory approvals are starting to be achieved for nanomedicines to treat a wide range of diseases. Angiogenesis therapies involve the inhibition of angiogenesis in oncology and ophthalmology, and stimulation of angiogenesis in wound healing and tissue engineering. This review aims to summarize nanotechnology-based strategies that have been explored in the broad area of angiogenesis. Lipid-based, carbon-based and polymeric nanoparticles, and a wide range of inorganic and metallic nanoparticles are covered in detail. Theranostic and imaging approaches can be facilitated by nanoparticles. Many preparations have been reported to have a bimodal effect where they stimulate angiogenesis at low dose and inhibit it at higher doses. [ABSTRACT FROM AUTHOR]

In this work, we demonstrate the fabrication of organic/inorganic hybrid materials based on living self-assembly. First, polyoxometalate (Keggin-type phosphotungstic acid, H3PW12O40) (POM) as an inorganic constituent and surface active ionic liquid (1-dodecyl-3-carboxymethyl imidazolium bromide, [N-C12, N′-COOH-Im]Br) (SAIL) as an organic constituent, were utilized to construct organic/inorganic hybrid nanofibers via an ionic self-assembly approach. The time-dependent evolution of the morphology from nanoparticles to nanofibers was investigated using various techniques (e.g. SEM, TEM, and UV/Vis). Hydrogen bonds and hydrophobic interactions were proved to play a dominant role in the evolution process. Next, of particular interest, POM/[N-C12, N′-COOH-Im]Br hybrid nanofibers were also obtained via a living self-assembly process by mixing metastable nanoparticle building blocks and seeds generated via ultrasonication of nanofibers. It is observed that the metastable nanoparticles directly bound to the end of the seeds, resulting in the formation of nanofibers. This strategy reduces the morphological evolution time from 7 days to 24 h, which suggests that the introduction of seeds greatly lowers the energy barrier in the morphological evolution process. Our study indicates that organic/inorganic hybrid materials can be obtained via living self-assembly. This will facilitate the use of functional organic/inorganic hybrid materials in various applications. Furthermore, this study represents an important step toward artificial systems that can mimic biological systems. [ABSTRACT FROM AUTHOR]

Here, we wrap Co3O4 nanoparticles with nitrogen-doped graphitic carbon nanofibers (Co3O4@NGFs) as a self-standing electrode for lithium-ion batteries. In this structure, graphitic carbon acts as a composite framework that enhances conductivity, accommodates volume expansion and increases contact with the electrolyte. Meanwhile, the porosity of Co3O4@NGFs not only facilitates rapid electron transfer, but also exposes more active sites for lithium storage. [ABSTRACT FROM AUTHOR]

Nitrogen-doped carbon nanofibers (NCNs) derived from chitin with an ultrafine nanofiber network structure (5–10 nm) showed a large specific surface area (426 m2 g−1). Small and uniform platinum nanoparticles (Pt NPs) were in situ synthesized on the chitin aerogel derived N doped ultra-thin carbon nanofibers (NCN-Pt) by combining adsorbing, freeze–drying and pyrolysis processes. The increased carbonization temperature from 800 to 1000 °C leads to a change of Pt NP average diameter from 2.85 ± 0.1 nm to 4.5± 0.1 nm. The unique three-dimensional mesoporous ultra-thin nanofiber network can protect the Pt NPs from aggregation, enabling resulting abundant active sites. NCN-Pt-900 exhibits enhanced HER activity with an overpotential of 34 mV and a Tafel slope of 39 mV decade−1 in comparison with commercial Pt/C (36 mV and 35 mV decade−1). Significantly, NCN-Pt-900 has excellent stability and durability for the HER. There were no obvious changes in LSV curves after 5000 cycles. Chitin is one of the most abundant natural polymers and is mainly derived from marine biomass. The synthesis strategy described herein is simple and scalable and it opens a new avenue to fabricate metal NPs on chitin aerogel derived N doped ultra-thin carbon nanofibers. [ABSTRACT FROM AUTHOR]

In this review article, we discuss the latest advances and future perspectives of microfluidics for micro/nanoscale catalyst particle synthesis and analysis. In the first section, we present an overview of the different methods to synthesize catalysts making use of microfluidics and in the second section, we critically review catalyst particle characterization using microfluidics. The strengths and challenges of these approaches are highlighted with various showcases selected from the recent literature. In the third section, we give our opinion on the future perspectives of the combination of catalytic nanostructures and microfluidics. We anticipate that in the synthesis and analysis of individual catalyst particles, generation of higher throughput and better understanding of transport inside individual porous catalyst particles are some of the most important benefits of microfluidics for catalyst research. [ABSTRACT FROM AUTHOR]

Single-walled carbon nanotubes (SWCNTs) are functionalized with copper hexacyanoferrate (CuHCF) nanoparticles to prepare solid substrates for sorption of cesium ions (Cs+) from liquid outflows. The high mechanical resistance and large electrical conductivity of SWCNTs are associated with the ability of CuHCF nanoparticles to selectively complex Cs+ ions in order to achieve membrane-like buckypapers presenting high loading capacity of cesium. The materials are thoroughly characterized using electron microscopy, Raman scattering, X-ray photoelectron spectroscopy and thermogravimetric analyses. Cs sorption isotherms are plotted after having measured the Cs+ concentration by liquid phase ionic chromatography in the solution before and after exposure to the materials. It is found that the total sorption capacity of the material reaches 230 mg g−1, and that about one third of the sorbed Cs (80 mg g−1) is selectively complexed in the CuHCF nanoparticles grafted on SWCNTs. The quantification of Cs+ ions on different sorption sites is made for the first time, and the high sorption rates open interesting outlooks in the integration of such materials in devices for the controlled sorption and desorption of these ions. [ABSTRACT FROM AUTHOR]

An introduction is presented that discusses several reports published within the issue on topics including fraction collection approach in capillary electrophoresis; electrochemical detection of cancer biomarkers, and brain and gonadal alterations in zebrafish through carbon nanoparticle.

Hydrophilic mesoporous carbon nanoparticles (MCNs) have been synthesized via an extremely facile precursor carbonization-in-hot solvent route. The synthesized MCNs show well-defined particle and pore size distribution at around 100 nm and 2.7 nm, respectively, and multicolor and upconversion photoluminescence, which endow the MCNs with multicolor/upconversion bioimaging and drug delivery properties. [ABSTRACT FROM AUTHOR]

A carbon nanofibers (CNFs)-supported palladium nanoparticles (Pd NPs) catalyst was fabricated by the combination of electrospinning, gas-phase hydrogenation reduction and subsequent calcination processes. Extensive characterization of the resulting carbon nanofibers-supported palladium nanoparticles catalyst was carried out. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) images reveal that the spherical Pd NPs are well-dispersed on the surfaces of the carbon matrix or embedded in the carbon matrix without agglomerating. The cubic phase of Pd formed during the reduction and carbonization processes. Most importantly, this carbon nanofibers-supported palladium nanoparticles hybrid material exhibited enhanced activity, excellent stabilization and recyclability. [ABSTRACT FROM AUTHOR]