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Atomically-dispersed iron-based electrocatalysts are promising substitutes for noble metal electrocatalysts because of excellent performance in oxygen reduction reaction (ORR). Rationally modulating the local coordination environment of the Fe site and optimizing the binding energy of oxygen reduction intermediates are effective strategies to optimize ORR activity. Herein, we report a new method in which Ni is introduced to construct NiFe dual single atoms and iron nanoclusters loaded on the nitrogen-doped carbon with a highly porous structure. This design plays a synergistic role of dual single atoms and clusters, optimizes the 3d orbital and Fermi level of Fe, breaks the symmetrical structure of Fe-N4, and effectively improves the adsorption/desorption behavior of the oxygen-containing intermediates. Electrochemical tests show FeNCs/NiFeSAs-NC has an excellent intrinsic activity. Theoretical calculations show the oxygen-containing species on the Ni active site will move to the middle of NiFe (bridge site connection) after optimization and that the key step is OH desorption, with a reaction energy of 0.27 eV. The electron exchange between NiFe-N6 and Fe-cluster is very strong, further indicating the introduction of Ni species and Fe clusters has a regulatory effect on the electronic structure of Fe-N4. [ABSTRACT FROM AUTHOR]

In this paper, lignin-based nanofiber materials with excellent adsorption performance were prepared by electrospinning technology with waste lignin as raw material and doped Ni-MOF-74. Through a series of characterization of the adsorbent, the effects of fiber morphology, pore size distribution, and doping Ni-MOF-74 on chlorobenzene adsorption performance were studied. It showed that doping Ni-MOF-74 could effectively increase the specific surface area of the adsorbent, enrich the pore structure, which was conductive to the adsorption. The results showed that Ni-MOF-74 doped lignin fiber exhibits excellent chlorobenzene adsorption performance compared with Ni-MOF-74 material and lignin fiber, and the maximum adsorption capacity can reach 58.49 g/g. According to the calculation of Langmuir equation, the chemical adsorption plays a leading role in the adsorption process of chlorobenzene. [ABSTRACT FROM AUTHOR]

This study focuses on the synthesis and characterization of Ag nanoparticle-decorated reduced graphene oxide (RGO) nanocomposites (Ag-RGO), which were obtained via a facile, green and efficient one-pot hydrothermal method. TEM results showed that the silver nanoparticles (20-50 nm) were uniformly attached onto RGO sheets with C/O ratio of 6.4 and 80% of sp2 carbon, obtained from XPS analysis. Compared with GO and RGO, the prepared Ag-RGO composites possessed significant antibacterial property; the minimum inhibitory concentration of Ag-RGO was just 31.25 μg/mL against Gram-positive bacteria S. aureus and Gram-negative bacteria E. coli. Particularly, the Ag-RGO nanocomposites released more Ag+ in acidic condition, promoting the produce of reactive oxygen species, which are acknowledged as disruption to the membrane integrity of the bacteria. Moreover, the Ag-RGO nanocomposites effectively dispersed and eliminated the maturely formed biofilm, showing superior advantages in responding to public health threats posed by biofilm-related infections. [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride (g-C3N4) is considered as an attractive, efficient and newly generated photocatalyst material owing to its distinct properties such as metal free, suitable band gap and high physicochemical stability. Nevertheless, the photocatalytic activity of pure g-C3N4 was limited by the fast recombination rate of photoinduced electron-hole pairs and relatively low specific surface area. In this study, we provide a new prospect to overcome the problem by using another suitable precursor urea-assisted copolymerization with thiourea which is expected to optimize the process of thermal condensation, inhibit agglomeration and improve the specific surface area; meanwhile, the formed isotype heterogeneous junction effectively inhibits charge carrier recombination. The formed g-C3N4 isotype heterojunction photocatalyst manifested significant improvement photocatalytic hydrogen production than the single and pure g-C3N4 sample. This significant enhanced photocatalytic performance is mainly ascribed to inhibited recombination, enriched active site and enlarged specific surface area. [ABSTRACT FROM AUTHOR]

A new process was developed to synthesize niobium diboride (NbB2) nanosheets with the dimension of about 500 nm and thickness of about 10 nm by using metal niobium, iodine and sodium borohydride as starting materials in an stainless steel autoclave at 700°C. Iodine was used to facilitate the exothermic reaction between metal niobium and sodium borohydride and the formation of NbB2. X-ray powder diffraction pattern indicated that the obtained product is hexagonal phase NbB2 with the calculated lattice constants a = 110 Å and c = 3.2929 Å. The obtained product was also studied by thermogravimetric analysis. It had good oxidation resistance below 400°C in air. [ABSTRACT FROM AUTHOR]

A solid-state route was developed to prepare zirconium diboride nanosheets with the dimension of about 500 nm and thickness of about 20 nm from zirconium dioxide, iodine and sodium borohydride at 700°C in an autoclave reactor. The obtained ZrB2 product was investigated by X-ray diffraction, scanning electron microscope and transmission electron microscopy. The obtained product was also studied by thermogravimetric analysis. It had good thermal stability and oxidation resistance below 400°C in air. Furthermore, the possible formation mechanism of ZrB2 was also discussed. [ABSTRACT FROM AUTHOR]

A simple one-step hydrothermal route was designed to decorate NiCoS on the surface of carboxylated multiwalled carbon nanotubes (MWCNT-COOHs) to form coaxial MWCNT-COOH@NiCoS hybrid. When employed as supercapacitor electrode material, the MWCNT-COOH@NiCoS electrode shows a large specific capacitance and excellent rate performance. Coupled with activated carbon (AC) negative electrode, the operating voltage of MWCNT-COOH@NiCoS//AC asymmetric supercapacitor (ASC) could be extended to 1.5 V. Moreover, the MWCNT-COOH@NiCoS//AC ASC device achieves a maximum energy density of 33.6 Wh kg at a power density of 375 W kg with good cycle stability (about 83.3% of capacity was retained after 2000 cycles at 3 A g). In addition, a MWCNT-COOH@NiCoS//AC ASC device can drive a mini-fan. Therefore, the coaxial MWCNT-COOH@NiCoS hybrid is a promising supercapacitor electrode material. [ABSTRACT FROM AUTHOR]

Hollow urchin-like iron-doped manganese dioxide (Fe-MnO) architectures were successfully prepared without any template or surfactant via a facile one-step hydrothermal route. Hollow urchin-like Fe-MnO architectures were made up of interleaving nanosheets, resulting in porous structures and high specific surface area. The formation mechanism of hollow urchin-like Fe-MnO architectures was proposed based on the Ostwald ripening process. When employed as supercapacitor electrode material, hollow urchin-like Fe-MnO delivered a specific capacitance of 203.3 F g at 250 mA g as well as a good capacity retention of 88.1% after 1000 cycles at 5 A g. Coupled with activated carbon (AC) negative electrode, Fe-MnO//AC asymmetric supercapacitor (Fe-MnO//AC ASC) achieved an energy density of 20.2 Wh kg at a power density of 225 W kg and 83.8% capacity retention after 1000 cycles at 3 A g, suggesting its potential applications for energy storage. [ABSTRACT FROM AUTHOR]

A simple hydrothermal route was developed to synthesis of rod-like manganese oxyhydroxide (MnOOH) and spindle-shaped manganese carbonate (MnCO) based on the redox reactions between potassium permanganate (KMnO) and β-cyclodextrin (β-CD) without extra surfactant or template. At the mass ratio between β-CD and KMnO of 0.25, MnOOH nanorods with the diameter about 40-400 nm and the length in the range of 2-10 μm could be facilely prepared in high yield. However, spindle-shaped MnCO microparticles were prepared when the mass ratio between β-CD and KMnO was increased to 1.5. The as-prepared products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and high-resolution transmission electron microscopy. The formation mechanisms of rod-like MnOOH and spindle-shaped MnCO were preliminarily discussed. [ABSTRACT FROM AUTHOR]

Silver nanowires have been synthesized by ethylene glycol reduction of silver nitrate with the assistance of polyvinyl pyrrolidone and sodium sulfide in a large scale. By adjusting the reaction temperature and Na2S content, silver nanowires with lengths up to 3−4 μm can be achieved in high yield. Scanning electron microscopy, transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected areas electron diffraction (SAED), and X-ray diffraction (XRD) have been employed to characterize silver nanowires. Platinum nanotubes with length about 3 μm can be prepared using as-prepared silver nanowires as sacrificial templates. Platinum nanotubes were characterized by TEM, SAED, and HRTEM. [ABSTRACT FROM AUTHOR]

NiFe2O4 nanoparticles and nanorods were synthesized by a facile hydrothermal treatment of Ni(DS)2 (Nickel dodecyl sulfate), FeCl3, and NaOH aqueous solution at 120 °C. The products were characterized by powder X-ray diffraction, transmission electron microscopy, and selected area electron diffraction. The magnetic properties were evaluated using a vibrating sample magnetometer. The probable mechanism of the formation of NiFe2O4 nanoparticles and nanorods was discussed. [ABSTRACT FROM AUTHOR]

A novel protection-reduction technique is developed for the preparation of silver nanoparticles, nanorods and wheatear-like supramolecular nanostructures at room temperature using silver potassium cyanide [KAg(CN)2] as a silver source, vitamin C (Vc) as a reducing agent and polyvinylpyrrolidone (PVP) as a protecting agent. The concentration of KAg(CN)2, the mole ratios of PVP/Vc and KAg(CN)2/Vc have significant effects on the formation and growth of these novel nanostructures. This method may be extended to prepare novel nanostructures of other metals. [ABSTRACT FROM AUTHOR]