Titanium Dioxide and N-Doped Carbon Hybrid Nanofiber Modulated Ru Nanoclusters for High-Efficient Hydrogen Evolution Reaction Electrocatalyst.

The designing and fabricating highly active hydrogen evolution reaction (HER) electrocatalysts that can superior to Pt/C is extremely desirable but challenging. Herein, the fabrication of Ru/TiO2/N-doped carbon (Ru/TiO2/NC) nanofiber is reported as a novel and highly active HER electrocatalyst through electrospinning and subsequent pyrolysis treatment, in which Ru nanoclusters are dispersed into TiO2/NC hybrid nanofiber. As a novel support, experimental and theoretical calculation results reveal that TiO2/NC can more effectively accelerate water dissociation as well as optimize the adsorption strength of *H than TiO2 and NC, thus leading to a significantly enhanced HER activity, which merely requires an overpotential of 18 mV to reach 10 mA cm-2, outperforming Pt/C in an alkaline solution. The electrolytic cell composed of Ru/TiO2/NC nanofiber and NiFe LDH/NF can generate 500 and 1000 mA cm-2 at voltages of 1.631 and 1.753 V, respectively. Furthermore, the electrolytic cell also exhibits remarkable durability for at least 100 h at 200 mA cm-2 with negligible degradation in activity. The present work affords a deep insight into the influence of support on the activity of electrocatalyst and the strategy proposed in this research can also be extended to fabricate various other types of electrocatalysts for diverse electrocatalytic applications.

Hierarchical Self-Assembly of Adhesive and Conductive Gels with Anion-Coordinated Triple Helicate Junctions.

The fabrication of anion-coordinated assemblies into functional soft materials remains a major challenge. To this end, four C2 -symmetric anion-binding ligands equipped with ortho-phenylene-bridged bis(urea) and amine or amide ends were designed, which generated A2 L3 triple helical architectures upon self-assembly with phosphate ions. Hierarchical intermolecular hydrogen bonds among the terminal amine/amide groups and urea moieties resulted in the formation of functional gels. The obtained gels were further applied for conductive adhesion between different surfaces, displaying excellent flexibility and selective wettability. The viscoelastic gels constructed from anion-coordinated assemblies described in this work represent the first example of a new class of anion-coordination-driven smart materials.

Activated carbon derived from melaleuca barks for outstanding high-rate supercapacitors.

Activated carbon (AC) was prepared via carbonizing melaleuca bark in an argon atmosphere at 600 °C followed with KOH activation for high-rate supercapacitors. This AC electrode has a high capacitance of 233 F g(-1) at a scan rate of 2 mV s(-1) and an excellent rate capability of ∼80% when increasing the sweep rate from 2 to 500 mV s(-1). The symmetric supercapacitor assembled by the above electrode can deliver a high energy density of 4.2 Wh kg(-1) with a power density of 1500 W kg(-1) when operated in the voltage range of 0-1 V in 1 M H2SO4 aqueous electrolyte while maintaining great cycling stability (less than 5% capacitance loss after 10 000 cycles at sweep rate of 100 mV s(-1)). All the outstanding electrochemical performances make this AC electrode a promising candidate for potential energy storage application.

NiFeRu/C and Ru, Fe-Ni5P4/C as complementary electrocatalyst for highly efficient overall water splitting.

Designing and fabricating highly competent and inexpensive electrocatalysts are highly desirable for application in electrocatalytic water splitting. In this study, we synthesized NiFeRu/C nanofibers and Ru, Fe dual-doped Ni5P4 (Ru, Fe-Ni5P4)/C nanofibers as complementary electrocatalysts for overall water splitting through electrospinning, carbonization, and phosphorization treatment, respectively. The NiFeRu/C nanofibers and Ru, Fe-Ni5P4/C nanofibers showed high hydrogen evolution reaction and oxygen evolution reaction activity, respectively, due to the presence of numerous exposed active sites and optimized adsorption capacity for the reaction intermediates contributed by the synergistic interaction among different metal components in the electrocatalysts. Hence, the assembled asymmetrical electrolytic cell effectively promoted overall water splitting, requiring a voltage of 1.569, 1.744, and 1.872 V to achieve a current density of 100, 500, and 1,000 mA cm-2, respectively, and it was better than Pt/C||IrO2. Additionally, the electrolytic cell could work at 500 mA cm-2 for 100 h without any noticeable deterioration in activity, which indicated that it was durable at high current density. In this study, we described a novel method for designing highly efficient electrocatalysts for overall water splitting.

NiMo solid-solution alloy porous nanofiber as outstanding hydrogen evolution electrocatalyst.

Developing a high-efficiency hydrogen evolution reaction (HER) electrocatalyst for the large-scale production of hydrogen is essential but challenging. In this study, we used NiMo solid-solution alloy porous nanofibers to develop a robust HER electrocatalyst through electrospinning, oxidization, and high-temperature reduction treatment. In 1 M KOH electrolyte, the fabricated NiMo solid-solution alloy porous nanofibers exhibited higher HER activity than Ni nanofibers, which required a low overpotential of 69, 208, and 300 mV at 100, 500, and 1000 mA cm-2, respectively, and had outstanding durability at 100 mA cm-2 over 60 h. We developed a promising candidate for a high-efficiency HER electrocatalyst, and our findings provided valuable information for fabricating highly robust alloy-based electrocatalysts.

Huge Primary Intermediate-grade Myofibroblastic Sarcoma in the Retroperitoneum.

Myofibroblastic sarcoma is exceedingly rare, with low-grade features in most cases, and rarely involves the retroperitoneum. The 2020 World Health Organization (WHO) classification of soft tissue tumours still lists only low-grade myofibroblastic sarcoma and shows no consensus on the definitions of high- and intermediate-grade myofibroblastic sarcomas, in contrast to the 2013 WHO classification. Surgical resection of the tumour and adjacent structures is the standard of care for most patients, and intermediate- and high-grade myofibroblastic sarcomas have very poor survival. We describe a patient with intermediate-grade myofibroblastic sarcoma in the retroperitoneum, who underwent en bloc resection and ureteroplasty without adjuvant therapy and was free of pain and any other discomfort during 19 months of follow-up. Key Words: Myofibroblastic sarcoma, Intermediate grade, Retroperitoneum, Surgery.

Fe and P dual-doped nickel carbonate hydroxide/carbon nanotube hybrid electrocatalysts for an efficient oxygen evolution reaction.

Designing cost-effective and highly active oxygen evolution reaction (OER) electrocatalysts is critical for large-scale hydrogen production from electrocatalytic water splitting. Herein, Fe and P dual-doped nickel carbonate hydroxide/carbon nanotubes (Fe, P-NiCH/CNTs) were fabricated through a solvothermal method. By virtue of the optimized electronic structure, improved conductivity and enriched active sites, the as-fabricated Fe, P-NiCH/CNT hybrid electrocatalyst exhibits superior OER activity, with a low overpotential of 222 mV at 20 mA cm-2 and robust durability, confirming its potential as a highly efficient OER electrocatalyst. Moreover, theoretical calculations demonstrate that the doped Fe and surface adsorbed PO43- can regulate the electronic structure of evolved NiOOH and decrease the energy barrier of the rate-determining step, thus leading to improved OER activity. The strategy presented in this work can also be employed to fabricate other transition metal carbonate hydroxides for various electrocatalytic applications.

Self-charging electrostatic face masks leveraging triboelectrification for prolonged air filtration.

Electrostatic adsorption is an important complement to the mechanical filtration for high-efficiency air filtering. However, the electrostatic charge decays with time, especially in humid conditions. In this work, a self-charging air filter is presented to capture airborne particles in an efficient and long-lasting manner without the need of external power sources. Leveraging the triboelectric effect between the electrospun poly(vinylidene fluoride) nanofiber film and nylon fabric, the self-charging air filter-based mask excited by breathing can continuously replenish electrostatic charges. As a result, its effective lifespan is up to 60 hours (including 30 hours of wearing), with a minimum filtration efficiency of 95.8% for 0.3-µm particles. The filtration efficiency and lifespan are significantly higher than those of a commercial surgical mask. Furthermore, we uncover the quantitative relation between filtration efficiency and surface electrostatic potential. This work provides an effective strategy to significantly prolong the electrostatic adsorption efficacy for high-performance air-filtering masks.

CoP and Ni2P implanted in a hollow porous N-doped carbon polyhedron for pH universal hydrogen evolution reaction and alkaline overall water splitting.

Developing low-cost and highly active bifunctional electrocatalysts for water splitting is very important but still remains a challenge. Herein, a novel bifunctional electrocatalyst composed of CoP and Ni2P nanoparticles implanted in a hollow porous N-doped carbon polyhedron (CoP/Ni2P@HPNCP) is synthesized by carbonization of Co/Ni-layered double hydroxide@zeolitic imidazolate framework-67 (Co/Ni-LDH@ZIF-67) followed by an oxidation and phosphorization strategy. The introduction of LDH can not only promote the formation of a hollow porous structure to supply more active sites, but also generate the CoP/Ni2P nanoheterostructure to afford extra active sites and modulate the electronic structure of the catalyst. As a result, CoP/Ni2P@HPNCP exhibits excellent pH universal hydrogen evolution reaction activity and alkaline oxygen evolution reaction activity. Furthermore, the electrolytic cell assembled from bifunctional CoP/Ni2P@HPNCP requires a cell voltage of 1.59 V in 1.0 M KOH at 10 mA cm-2, revealing its potential as a high performance bifunctional electrocatalyst.

Multi-channel V-doped CoP hollow nanofibers as high-performance hydrogen evolution reaction electrocatalysts.

Rational design and construction of high-efficiency and low-cost non-noble metal-based electrocatalysts for the hydrogen evolution reaction (HER) is critical for future renewable energy systems. Herein, a multi-channel V-doped CoP (MC-V-CoP) hollow nanofiber is fabricated via electrospinning and a subsequent oxidation/phosphorization process. The formation of a multi-channel hollow structure and V doping can enlarge the exposure of active sites, facilitate the electron transfer and tune the electronic structure of the active sites, resulting in the enhancement of the HER performance. As a result, the MC-V-CoP hollow nanofiber exhibits excellent HER activity with a low overpotential of 65 and 189 mV at 10 and 300 mA cm-2 in alkaline medium, respectively. This is superior to the commercial 20 wt% Pt/C catalyst at a high current density (212 mV at 300 mA cm-2), manifesting its outstanding performance toward the HER at a high current density. In addition, the MC-V-CoP hollow nanofiber also exhibits outstanding HER activity in neutral medium. The proposed strategy for fabricating multi-channel hollow nanofibers can also be used to prepare other transition metal phosphides for advanced electrochemical applications.

An improved separation method of multi-components signal for sensing based on time-frequency representation.

In many situations, it is essential to analyze a nonstationary signal for sensing whose components not only overlapped in time-frequency domain (TFD) but also have different durations. In order to address this issue, an improved separation method based on the time-frequency distribution is proposed in this paper. This method computes the time-frequency representation (TFR) of the signal and extracts the instantaneous frequency (IF) of components by a two-dimensional peak search in a limited area in which normalized energy is greater than the set threshold value. If there is more than one peak from a TFR, IFs of components can be determined and linked by a method of minimum slope difference. After the IFs are obtained, the improved time-frequency filtering algorithm is used to reconstruct the component of the signal. We continue this until the residual energy in the TFD is smaller than a fraction of the initial TFD energy. Different from previous methods, the improved method can separate the signal whose components overlapped in TFR and have different time durations. Simulation results have shown the effectiveness of the proposed method.

Electrospun Polytetrafluoroethylene Nanofibrous Membrane for High-Performance Self-Powered Sensors.

Polytetrafluoroethylene (PTFE) is a fascinating electret material widely used for energy harvesting and sensing, and an enhancement in the performance could be expected by reducing its size into nanoscale because of a higher surface charge density attained. Hence, the present study demonstrates the use of nanofibrous PTFE for high-performance self-powered wearable sensors. The nanofibrous PTFE is fabricated by electrospinning with a suspension of PTFE particles in dilute polyethylene oxide (PEO) aqueous solution, followed by a thermal treatment at 350 °C to remove the PEO component from the electrospun PTFE-PEO nanofibers. The obtained PTFE nanofibrous membrane exhibits good air permeability with pressure drop comparable to face masks, excellent mechanical property with tensile strength of 3.8 MPa, and stable surface potential of - 270 V. By simply sandwiching the PTFE nanofibrous membrane into two pieces of conducting carbon clothes, a breathable, flexible, and high-performance nanogenerator (NG) device with a peak power of 56.25 µW is constructed. Remarkably, this NG device can be directly used as a wearable self-powered sensor for detecting body motion and physiological signals. Small elbow joint bending of 30°, the rhythm of respiration, and typical cardiac cycle are clearly recorded by the output waveform of the NG device. This study demonstrates the use of electrospun PTFE nanofibrous membrane for the construction of high-performance self-powered wearable sensors.

Flexible Transparent Molybdenum Trioxide Nanopaper for Energy Storage.

A flexible transparent molybdenum trioxide nanopaper, assembled via ultralong molybdenum trioxide nanobelts, displays an excellent average transmittance of ≈90% in the visible region. The free-standing nanopaper electrode delivers an outstanding specific capacitance of 1198 F g(-1) and shows an excellent long-term stability performance over 20 000 cycles with a retention rate of 99.1%.

The Fabrication of Carbon Nanofibers Paper Supported CoO4 Nanocomposite and Their Electrochemical Properties.

A hierarchical network architecture consisting of Co3O4 nanoflakes network (nanonet) coats on a carbon fiber paper. For this 3 dimension (3D) architecture, the electrode shows ideal pseudocapacitive behavior and the maximum specific capacitance of 210 F/g can be reached at the constant current density of 1 A/g in 1 M KOH electrolyte, still retaining 85% of the initial capacitance after 1000 cycles of repeating charge-discharge. The improved capacity may be attributed to the unique hierarchical network structures, which improve electron/ion transport, enhancing the kinetics of redox reactions and facilitate facile stress relaxation during cycling.

Oxygen- and Nitrogen-Enriched 3D Porous Carbon for Supercapacitors of High Volumetric Capacity.

Efficient utilization and broader commercialization of alternative energies (e.g., solar, wind, and geothermal) hinges on the performance and cost of energy storage and conversion systems. For now and in the foreseeable future, the combination of rechargeable batteries and electrochemical capacitors remains the most promising option for many energy storage applications. Porous carbonaceous materials have been widely used as an electrode for batteries and supercapacitors. To date, however, the highest specific capacitance of an electrochemical double layer capacitor is only ∼200 F/g, although a wide variety of synthetic approaches have been explored in creating optimized porous structures. Here, we report our findings in the synthesis of porous carbon through a simple, one-step process: direct carbonization of kelp in an NH3 atmosphere at 700 °C. The resulting oxygen- and nitrogen-enriched carbon has a three-dimensional structure with specific surface area greater than 1000 m(2)/g. When evaluated as an electrode for electrochemical double layer capacitors, the porous carbon structure demonstrated excellent volumetric capacitance (>360 F/cm(3)) with excellent cycling stability. This simple approach to low-cost carbonaceous materials with unique architecture and functionality could be a promising alternative to fabrication of porous carbon structures for many practical applications, including batteries and fuel cells.

Low-cost and facile one-pot synthesis of pure single-crystalline ε-Cu(0.95)V2O5 nanoribbons: high capacity cathode material for rechargeable Li-ion batteries.

Pure single-crystalline ε-Cu(0.95)V(2)O(5) nanoribbons have been successfully synthesized via a facile one-pot solvothermal route using low-cost raw materials. The obtained materials can react electrochemically with 2.64 Li in a reversible fashion and thus greatly expands the range of cathode choices.

Preparation of SrAl2O4:Eu(2+), Dy(3+) fibers by electrospinning combined with sol-gel process.

One-dimensional SrAl(2)O(4):Eu(2+), Dy(3+) fibers were fabricated by a simple electrospinning combined with sol-gel process. X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and photoluminescence were used to characterize the fibers. The results show that the phase structure of SrAl(2)O(4):Eu(2+), Dy(3+) belongs to a monoclinic one, the composite fibers and fibers calcined at high temperature remain the original one-dimensional texture, and the SrAl(2)O(4):Eu(2+), Dy(3+) was a green emission.