Quiescent hydrothermal synthesis of reduced graphene oxide–periodic mesoporous silica sandwich nanocomposites with perpendicular mesochannel alignments

Quiescent hydrothermal conditions were applied to synthesis of the sandwich nanocomposites of reduced graphite oxide (rGO) and periodic mesoporous silica (PMS) with vertically aligned mesochannels. It was found that the formation of the PMS–rGO–PMS sandwich structure is very sensitive to the surface and synthesis conditions. Although a higher temperature hydrothermal condition promotes reduction of GO and formation of bulky mesoporous nanoparticles, quiescent hydrothermal condition can serve as an alternative approach to obtain the unusual nanocomposites and slightly promote the structural stability of PMS on the surface of rGO.     

Combination of α-Fe2O3, CdS and reduced graphene oxide: high-performance and recyclable visible light photocatalysis

A magnetic heterogeneous α-Fe₂O₃/CdS-RGO (RGO: reduced graphene oxide) composite photocatalyst was synthesized using the one-step hydrothermal method. The α-Fe₂O₃ and CdS nanoparticles with a diameter range of 20~60 nm were synchronously loaded/distributed on the surface of RGO. The as-synthesized α-Fe₂O₃/CdS-RGO nanocomposites were analyzed using X-ray diffraction, Fourier transform-infrared spectra, BET surface area, scanning electron microscopy, transmission electron microscopy, UV–Vis diffusive reflectance spectra and Raman spectroscopy. Compared with the pure CdS, α-Fe₂O₃ and α-Fe₂O₃/CdS nanoparticles, the α-Fe₂O₃/CdS-RGO nanocomposites expanded the adsorption range of visible-light, and showed significant photocatalytic performance and cyclic stability for degradation of methylene blue in visible light. Also, the remarkable catalytic performances mainly depend on its special structure of the α-Fe₂O₃/CdS-RGO, which enabled the effective separation of the electron–hole pairs. These attractive features make the α-Fe₂O₃/CdS-RGO nanocomposite to be a photocatalyst with great application potential in water pollutants treatment.     

Synthesis of reduced graphene oxide functionalized with methyl red dye and its role in enhancing photoactivity in TiO2–IL/WO3 composite for toluene degradation

Research on Chemical Intermediates - A nanostructured composite material was produced through sol–gel-assisted ionic liquid (IL) synthesized TiO2, WO3 and functionalized reduced graphene...     

Non-aqueous approach to the preparation of reduced graphene oxide/α-Ni(OH)2 hybrid composites and their high capacitance behavior

Reduced graphene oxide/α-Ni(OH)(2) composites present high electrochemical properties, with specific capacitance of 1215 F g(-1) at 5 mV s(-1) scan rate, since graphene as conductive matrix provides electronic conduction pathway.     

Electrochemical biosensor for amplified detection of Pb2+ based on perfect match of reduced graphene oxide–gold nanoparticles and single-stranded DNAzyme

Analytical and Bioanalytical Chemistry - In this study, a sensitive amplification strategy for Pb2+ detection using reduced graphene oxide (RGO) and gold nanoparticles (AuNPs) was proposed....     

High-performance (NH4)2V6O16·0.9H2O nanobelts modified with reduced graphene oxide for aqueous zinc ion batteries

Ammonium vanadate has been considered as a competitive high-performance cathode material for aqueous Zn-ion batteries. However, it still suffers from insufficient rate capability and poor cyclability due to the low electronic conductivity. Herein, (NH₄)₂V₆O₁₆·0.9H₂O nanobelts with reduced graphene oxide (RGO) modification are synthesized by one-step hydrothermal reaction. Benefiting from the addition of RGO, an excellent electrochemical performance of (NH₄)₂V₆O₁₆·0.9H₂O@RGO nanobelts can be obtained. The (NH₄)₂V₆O₁₆·0.9H₂O@RGO displays a high-rate capacity and a high energy density of 386 Wh/kg at 72 W/kg. In particular, after 1000 cycles at 5 A/g, the capacity remains at 322 mAh/g with 92.8% capacity retention. In addition, the key reaction mechanisms of reversible Zn²⁺insertion/extraction in (NH₄)₂V₆O₁₆·0.9H₂O@RGO are clarified.     

Improved performances of β-Ni(OH)2@reduced-graphene-oxide in Ni-MH and Li-ion batteries

Incorporation of reduced graphene oxide into β-Ni(OH)(2) presents high performances with specific discharge capacity of 283 mA hg(-1) after 50 cycles in Ni-MH batteries, and 507 mA hg(-1) after 30 cycles in Li ion batteries.     

Sensitive and selective stripping voltammetric determination of copper(II) using a glassy carbon electrode modified with amino-reduced graphene oxide and β-cyclodextrin

We describe a square wave anodic stripping voltammetric (SWASV) platform for the determination of Cu(II). It is based on the use of amino-reduced graphene oxide (NH₂-rGO) and β-cyclodextrin (β-CD) that were self-assembled on the surface of a glassy carbon electrode (GCE). The hydrophilicity and electrochemical performance of the resulting modified GCE were investigated by measurement of static contact angles, cyclic voltammetry and electrochemical impedance spectroscopy. Cu(II) was reduced at −1.1 V and then reoxidized at −0.012 V. Under optimum experimental conditions, the modified GCE exhibited excellent SWASV response in that the stripping peak currents (when sweeping between −0.3 and +0.25 V) depends on the concentration of Cu(II) in the 30 nM to 100 μM range. The limit of detection is 2.8 nM (at 3σ/slope). The modified GCE displaying good reproducibility, is stable, highly sensitive and selective. It was successfully applied to the determination of Cu(II) in synthetic and real water samples. The fast electron transfer rate and simple preparation of the NH₂-rGO/β-CD composite makes it a promising electrode material for applications in sensing of heavy metal ions.

Amino-modified rGO and β-cyclodextrin form an attractive material for use in an electrochemical platform for highly sensitive and selective determination of Cu(II).

     

Conversion efficiency of γ/β-MnO2 in composites with natural graphite and carbon nanotubes in a prototype lithium battery

Chemically synthesized manganese dioxide γ/β-MnO₂ was studied in composites with multi-walled carbon nanotubes and natural graphite of EUZ-M brand was studied in the redox reaction with lithium. It was shown that nanometer carbon electron-conducting filler is advantageous over the micrometer filler (EUZ-M) in the efficiency of influence exerted on power characteristics and cycling capacity of a prototype lithium battery with a cathode based on γ/β-MnO₂. The effective chemical diffusion coefficient of lithium ions in MnO₂ composites with multi-walled carbon nanotubes and EUZ-M was estimated and hodographs of electrodes based on γ/β-MnO₂ without a carbon additive and with EUZ-M, brought in contact with an electrolyte, were analyzed.     

Improved Synthesis of 1‐Benzenesulfinyl Piperidine and Analogs for the Activation of Thioglycosides in Conjunction with Trifluoromethanesulfonic Anhydride*

An improved protocol for the large‐scale production of 1‐benzenesulfinyl piperidine and other sulfinamides is described. It is demonstrated that 1‐benzenesulfinyl pyrrolidine and N,N‐diethyl benzenesulfinamide function analogously to 1‐benzenesulfinyl piperidine in the trifluoromethanesulfonic anhydride‐mediated activation of thioglycosides, and that their less crystalline nature enables them to be used at ?78°C as opposed to the ?60°C required to keep 1‐benzenesulfinyl piperidine in solution. N,N-Dicyclohexyl benzenesulfinamide does not activate thioglycosides in combination with trifluoromethanesulfonic anhydride, which is attributed to its greater steric bulk.     

Electrochemical immunosensor for the carcinoembryonic antigen based on a nanocomposite consisting of reduced graphene oxide,gold nanoparticles and poly(indole-6-carboxylic acid)

We describe a label-free electrochemical immunosensor for the carcinoembryonic antigen (CEA). It is based on a nanocomposite consisting of electrochemically reduced graphene oxide, gold nanoparticles (AuNPs), and poly(indole-6-carboxylic acid). Coupled to nanoparticle-amplification techniques and modified with ionic liquid (IL), this immunoassay shows high sensitivity and good selectivity for CEA. At the best working voltage of 0.95 V (vs. Ag/AgCl), the lower detection limit is 0.02 ng·mL^?1, and the response to CEA is linear in the range from 0.02 to 90 ng·mL^?1. The method was applied to the determination of CEA in spiked serum samples and gave recoveries in the range from 98.5 % to 102 %.

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Graphical abstract A label-free electrochemical immunosensor was fabricated for the carcinoembryonic antigen (CEA) with a detection limit of 0.02 ng·mL^?1. It is based on a nanocomposite consisting of electrochemically reduced graphene oxide (erGO), gold nanoparticles (Au NP), and poly(indole-6-carboxylic acid) (PICA).

     

Preparation of polyethylene oxide with 4-amino-N-(2-pyrimidinyl) benzene sulfonamide and diethylenetriaminepentaacetic acid end groups and its enrichment in tumour tissues

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Anomalies of the partition coefficient and properties of crystals in the region of low concentrations of an isomorphous admixture. 1. Unusual decomposition of solid solutions of the NaCl—CdCl2 system

Solid solutions NaCl—CdCl₂ were studied in an interval of CdCl₂ concentrations of 0.05—3 mol.% by Raman spectroscopy. The molecular form Na₂CdCl₄ decomposes: Na₂CdCl₄ 2Na⁺ + Cd²⁺ + 2Cl₂ ^– + 2e^–; 2Na + 2e^– 2Na⁰. Free sodium atoms form color centers of crystal (F centers) in the region of jumpwise changing the partition coefficient of CdCl₂ in NaCl (K jump).