Growth of copper sulfide dendrites and nanowires from elemental sulfur on TEM Cu grids under ambient conditions

Copper sulfide dendrites and subsequent uniform nanowires up to tens of micrometers long can be grown on carbon-coated transmission electron microscopy (TEM) Cu grids from elemental sulfur at room temperature under ambient conditions without any solvent and surfactants. TEM and high-resolution TEM studies demonstrated the morphology evolution of Cu?S from dendrites into ultra-long nanowires with increasing ageing time. The sulfur species influenced significantly the growth rate of Cu?S dendrites and nanowires, but the final morphology remained the same. The native oxide on the surface of Cu grids played a critical role in the formation of Cu?S dendrites and nanowires. The crystal structures and phase purity of Cu?S samples were confirmed by x-ray diffraction (XRD) and energy dispersive x-ray spectroscopy (EDX). A solid-liquid-solid growth model may be considered a potential mechanism in Cu?S morphology evolution on the basis of the experimental results. Most importantly, the present study provides a simple and environmentally friendly route for the growth of one-dimensional (1D) Cu?S on Cu substrate.     

Characteristics of organic light emitting diodes with copper iodide as injection layer

We have studied the use of a thin copper iodide (CuI) film as an efficient injection layer of holes from indium tin oxide (ITO) anode in a light-emitting diode structure based on tris-8-hydroxyquinoline aluminium (Alq3). The results of impedance analysis of two types of diode structures, ITO/CuI/Alq3/poly(ethylene glycol) dimethyl ether/Al and ITO/Alq3/poly(ethylene glycol) dimethyl ether/Al, are presented. Comparative analysis of their current density-voltage, luminance-voltage and impedance characteristics shows that presence of CuI layer facilitates injection of holes from ITO anode into the light-emitting layer Alq3 and increases electroluminescence efficiency of the organic light emitting diodes.     

Measurement of valve oxygen diffusion for bag-in-box applications under three possible ambient conditions

The shelf life of wine is often markedly reduced by the ingress of atmospheric oxygen through the valve or spout. The principal objective of this study was to evaluate various types of valves by means of a capture cell which provides the flexibility to evaluate performance under three possible ambient conditions (23, 30 and 38°C). With the basic statistics obtained we were able to estimate a data confidence interval (95%) and suggest predictive equations useful to buyers in the industry.     

g-C3N4 quantum dot decorated MoS2/Fe3O4 as a novel recoverable catalyst for photodegradation of organic pollutant under visible light

In this research, zero-dimensional (quantum dots) of graphitic carbon nitride (g-C₃N₄) and Fe₃O₄ nanoparticles were decorated on MoS₂ nanosheets to prepare MoS₂/Fe₃O₄/g-C₃N₄ quantum dots. Photocatalytic activities of newly synthesized nanocatalyst were investigated by the degradation of methylene blue (MB) and methyl orange (MO) under visible LED lamp light. In these degradation reactions, the parameters effective such as dyes concentration, pH, amount of catalyst, and irradiation time were also investigated. The systematic investigations revealed that 10 mg of MoS₂/Fe₃O₄/g-C₃N₄QDs catalyst was optimum to degrade 10 mg/L of MB and 40 mg of nanocatalyst to degrade 10 mg/L of MO with 60 W of LED irradiation. Nanocomposite can act as an excellent photocatalyst for degradation of MB and MO at short time intervals and also can be easily separated by an external magnet and reused several times. The kinetic data acquired for the degradation of dyes were matched to first-order rate equations, and also the apparent rate constants for the degradation of MB and MO were calculated as follows: K?=?0.285 min^?1 and K?=?0.263 min^?1, respectively. The novelty of catalyst is due to metal (Mo) and non-metal (S) in the structure of substrate (MoS₂), so Fe₃O₄ and g-C₃N₄ QDs can be strongly connected to the substrate. The structure and morphology of prepared nanocomposite were characterized by X-ray diffraction (XRD), vibrating sample magnetometer (VSM), transmission electron microscopy (TEM), scanning electron microscopy (SEM) energy dispersive X-ray spectroscopy (EDS), and UV–Vis spectroscopy.

     

Electrospray-assisted laser desorption/ionization mass spectrometry for continuously monitoring the states of ongoing chemical reactions in organic or aqueous solution under ambient conditions

Electrospray-assisted laser desorption/ionization (ELDI) combined with mass spectrometry allows chemical and biochemical compounds to be characterized directly from hydrophilic and hydrophobic organic solutions mixed with carbon powders under ambient conditions. Organic and inorganic compounds dissolved in polar or nonpolar solvent such as methanol, tetrahydrofuran, ethyl acetate, toluene, dichloromethane, or hexane can be detected using this ambient ionization technique without prior pretreatment. We have used this technique to monitor the progress in several ongoing reactions: the epoxidation of chalcone in ethanol, the chelation of ethylenediaminetetraacetic acid with copper and nickel ions in aqueous solution, the chelation of 1,10-phenanthroline with iron(II) in methanol, and the tryptic digestion of cytochrome c in aqueous solution. Liquid-ELDI analyses simply require irradiation of the surface of the sample solution with a pulsed ultraviolet laser; the laser energy is adsorbed by the carbon powder presuspended in the sample solution; the absorbed laser energy is then transferred to the surrounding solvent and to the analyte molecules in the solution, leading to their desorption; the desorbed gaseous analyte molecules are then postionized within an electrospray (ESI) plume to generate ESI-like analyte ions.     

Combination of MoS2 nanopetals with Ag nanoparticles decorated graphene oxide for boosting photocatalytic abatement of recalcitrant pollutants under visible light irradiation

Herein, various weight ratios (1:1, 1:3, and 3:1) of MoS₂/GO composites decorated with Ag nanoparticles (named as MAG) have been prepared by microwave-assisted route. XRD and XPS investigations indicated the catalyst crystallinity and elemental oxidation states. Morphological analysis revealed presence of small MoS₂ nanopetals scattered on GO sheets with Ag NPs dispersed on surface whereas BET-analysis disclosed its excellent surface area (～88 m²/g). Optical properties of MAG catalysts revealed that they were highly visible-light active, with a bandgap of 2.15 eV and a lower charge recombination rate. Excellent efficiency was observed for TC (90.7%; 0.0186 min^?1) and FIP-degradation (85.2%; 0.0177 min^?1) with 4 mg MAG (3:1) catalyst at neutral pH under visible-light irradiation owing to high synergistic interaction (～2.21) in the composite. Effects of catalyst amount, pH, and effective area of illumination on degradation were investigated. High reusable nature of the catalyst (65% (TC) and 58% (FIP) efficiency after 5 cycles) was supported by post-photocatalytic characterization studies. Photodegradation products of TC were determined via LC-MS studies. Holes and hydroxyl radicals were majorly involved in degradation process revealed by trapping studies. High COD (70.4%) and TOC (55.1%) removal rates confirm high photo-mineralization of real-wastewater without any pre-treatment. The current investigation, combined with comparative literature, illustrates real-world potential of MAG catalysts for eradication of resistant pollutants.     

Fabrication of isoreticular metal-organic framework coated capillary columns for high-resolution gas chromatographic separation of persistent organic pollutants

The unusual properties of metal-organic frameworks (MOFs), such as permanent nanoscale porosity, high surface area, uniformly structured cavities, and the availability of in-pore functionality and outer-surface modification, are advantageous for diverse applications. However, most existing methods for the synthesis of nanosized MOFs require an activation procedure or auxiliary stabilizing agents. Here we report a 1-min, room-temperature approach for the synthesis of nanosized isoreticular MOFs (IRMOFs) to fabricate IRMOF coated capillary columns for the high-resolution gas chromatographic separation of persistent organic pollutants (POPs), including polychlorinated biphenyls (PCBs), polyaromatic hydrocarbons (PAHs), polybrominated diphenylethers (PBDEs), and hexachlorocyclohexanes (HCHs). The developed method allows the synthesis of well-shaped nanosized IRMOFs within 1 min at room temperature without the need for any activation procedure or auxiliary stabilizing agents. The IRMOF coated capillary columns offer good separation efficiency that is generally comparable to that of a commercial HP-5MS column for POPs. The IRMOF-1 and IRMOF-3 coated capillary columns gave the theoretical plate values of 2293 and 2063 plates m(-1) for naphthalene, respectively, which are slightly smaller than those with a HP-5MS column (2845 plates m(-1)). The IRMOF-1 coated capillary column offered good resolution for the separation of several intractable PAH isomer pairs, such as anthracene/phenanthrene, benzo[a]anthracene/chrysene, and benzo[b]fluoranthene/benzo[k]fluoranthene, with resolutions of 3.0, 1.1, and 4.1, respectively, which were difficult to be baseline separated on a HP-5MS column with a resolution of 1.0. In addition, the IRMOF-1 and IRMOF-3 coated capillary columns offered a clear group separation of the PCB isomers and a linear range covering three orders of magnitude. The relative standard deviations for the five replicate separations of PAHs were 0.23-0.26% and 2.1-4.5% for retention time and peak area, respectively. The fabricated IRMOF coated capillary columns have been shown to be very promising for the separation of POPs with good reproducibility, high resolution, great selectivity, and a wide linear range.     

Versatile new ion source for the analysis of materials in open air under ambient conditions

A new ion source has been developed for rapid, noncontact analysis of materials at ambient pressure and at ground potential. The new source, termed DART (for "Direct Analysis in Real Time"), is based on the reactions of electronic or vibronic excited-state species with reagent molecules and polar or nonpolar analytes. DART has been installed on a high-resolution time-of-flight mass spectrometer (TOFMS) that provides improved selectivity and accurate elemental composition assignment through exact mass measurements. Although DART has been applied to the analysis of gases, liquids, and solids, a unique application is the direct detection of chemicals on surfaces without requiring sample preparation, such as wiping or solvent extraction. DART has demonstrated success in sampling hundreds of chemicals, including chemical agents and their signatures, pharmaceutics, metabolites, peptides and oligosaccharides, synthetic organics, organometallics, drugs of abuse, explosives, and toxic industrial chemicals. These species were detected on various surfaces, such as concrete, asphalt, human skin, currency, airline boarding passes, business cards, fruits, vegetables, spices, beverages, body fluids, horticultural leaves, cocktail glasses, and clothing. DART employs no radioactive components and is more versatile than devices using radioisotope-based ionization. Because its response is instantaneous, DART provides real-time information, a critical requirement for screening or high throughput.     

NASICON devices attached with Li2CO3-BaCO3 auxiliary phase for CO2 sensing under ambient conditions

NASICON (Na₃Zr₂Si₂PO₁₂)—based electrochemical devices, constructed in a gas-separation type or planar type, were attached with a Li₂CO₃-BaCO₃ (1:2 in molar ratio) auxiliary phase to investigate their CO₂ sensing properties under ambient conditions. The devices were found to be far more resistant to the disturbance by a change in relative humidity (RH) than those using Na₂CO₃ or NaHCO₃ auxiliary phase. The EMF was correlated linearly with the logarithm of CO₂ concentration in the range of 0.03–50% CO₂ at 30°C, and the linear correlation shifted up or down only slightly with a change in RH between 30 and 90%. For a change in operating temperature, the CO₂ sensing capability was kept almost the same at 45°C, while it was deteriorated significantly at 60 and 75°C, especially in the lower RH range. Applicability of a cobalt oxide bronze (Na_0.6CoO₂) as a solid reference electrode for the planar type device was also investigated. The devices using the bronze reference electrode exhibited the CO₂ sensing capability as good as those using the Au reference electrode did. In addition, the bronze electrode was found to much improve the reproducibility of the EMF to a fixed concentration of CO₂ among devices.     

Microwave-enhanced synthesis of magnetic porous covalent triazine-based framework composites for fast separation of organic dye from aqueous solution

A novel type of magnetic porous carbonaceous polymeric material, CTF/Fe(2)O(3) composite (CTF = covalent triazine-based framework), has been synthesized by a facile microwave-enhanced high-temperature ionothermal method. By selecting ZnCl(2) as a reaction medium and the Lewis acid catalyst, and choosing FeCl(3)·6H(2)O as an iron oxide precursor, a series of CTF/Fe(2)O(3) composites with different γ-Fe(2)O(3) contents has been prepared in 60 min. The resulting samples were characterized by the X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibration sample magnetometer (VSM), and N(2) sorption-desorption isotherms. The obtained CTF/Fe(2)O(3) composites exhibit high surface areas (930-1149 m(2) g(-1)), and their saturation magnetizations at 300 K vary from 1.1 to 5.9 emu g(-1), depending respectively on different Fe(2)O(3) contents (6.43-12.43 wt%) in the CTF/Fe(2)O(3) composites. The CTF/Fe(2)O(3) composites were applied to remove organic dye from aqueous solution by selecting methyl orange as a model molecule, and both high adsorption capacity (291 mg g(-1), corresponding to 0.889 mmol g(-1)) and fast adsorption kinetics (k(ads) = 4.31 m(2) mg(-1) min(-1)) were observed.     

Absorption of water into organic solvents used for electrochemistry under conventional operating conditions

Many solvents used for electrochemistry can be dried to <1 × 10(-3) M water content by storing the solvents over 3 ? molecular sieves in a nitrogen or argon atmosphere. However, as soon as the solvents are placed in an electrochemical cell, the water content increases significantly. Karl Fischer coulometric titrations were conducted on several predried solvents commonly used for electrochemistry (acetonitrile, dichloromethane, N,N-dimethylformamide, and dimethyl sulfoxide) in a controlled-humidity environment (30%, 50%, and 70% relative humidity) to determine the rate of moisture uptake into the organic solvents when used under typical electrochemical conditions (either in an electrochemical cell under a nitrogen atmosphere or in an electrochemical cell directly exposed to the atmosphere). The results in this study give guidelines for estimating the water content of organic solvents under conventional electrochemical operating conditions.     

Linearised model for PV panel power output variation with changes in ambient conditions

In closed loop control of PV systems it is important to model the small signal variation of PV panel array output with ambient conditions, namely irradiation and temperature. Changes in these conditions act as a disturbance to the system, but this disturbance needs to be reflected in terms of the quantity being controlled, which can be the PV panel current or the real power. In this work a linearised model is derived to relate the change in system input, namely: irradiance and temperature, with its output, namely: array current and power. The proposed model is experimentally verified with tests run on PV panels, when they are subjected to varying irradiation and temperature conditions in the laboratory. The experimental results confirm the accuracy of the linearised PV panel model.     

Orientation controlled preparation of nanoporous carbon nitride fibers and related composite for gas sensing under ambient conditions

Creating pores in suprastructures of two-dimensional (2D) materials while controlling the orientation of the 2D building blocks is important in achieving large specific surface areas and tuning the anisotropic properties of the obtained functional hierarchical structures.In this contribution,we report that arranging graphitic carbon nitride (g-C3N4) nanosheets into one-dimensional (1D) architectures with controlled orientation has been achieved by using 1D oriented melem hydrate fibers as the synthetic precursor via a polycondensation process,during which the removal of water molecules and release of ammonia gas led to the creation of pores without destroying the 1D morphology of the oriented structures.The resulting porous g-C3N4 fibers with both meso-and micro-sized pores and largely exposed edges exhibited good sensing sensitivity and selectivity towards NO2.The sensing performance was further improved by hybridization of the porous fibers with Au nanoparticles (Au NPs),leading to a detection limit of 60 ppb under ambient conditions.Our results suggest that the highly porous g-C3N4 fibers and the related hybrid structures with largely exposed graphitic layer edges are excellent sensing platforms and may also show promise in other electronic and electrochemical applications.     

BiOBr and BiOCl decorated on TiO2 QDs: Impressively increased photocatalytic performance for the degradation of pollutants under visible light

BiOBr and BiOCl were decorated on TiO₂ QDs through n-p-p heterojunctions by a simple strategy and they were applied for degradation of three organic dyes upon visible illumination. The obtained photocatalysts were analyzed via XRD, FESEM, EDX, UV–vis DRS, PL, BET, TEM, HRTEM, FT-IR, EIS, XPS, and transient photocurrent measurements. The TiO₂ QDs/BiOBr/BiOCl nanocomposite with 20% wt. of BiOBr and 30% wt. of BiOCl displayed superior photoability in the degradation of methylene blue, rhodamine B, and fuchsine, which was almost 34.5, 176, and 78.7-times larger than TiO₂ and 27.8, 13.5, and 51.5-folds greater than TiO₂ QDs, respectively. The results show that the construction of intimate n-p-p heterojunctions between BiOBr, TiO₂ QDs, and BiOCl counterparts leads to enhanced visible-light harvesting and improved charge separation, resulted efficiently increased photocatalytic activity. The trapping results proved that h⁺, ^•O₂⁻, and OH^• species have considerable effects on the degradation reaction. We think that the improved efficiency of the ternary TiO₂ QDS/BiOBr/BiOCl photocatalyst is a splendid alternative for the removal of toxic contaminants from wastewater.     

Aldehyde-alcohol reactions catalyzed under mild conditions by chromium(III) terephthalate metal organic framework (MIL-101) and phosphotungstic acid composites

Porous materials based on chromium(III) terephthalate metal organic frameworks (MIL-101) and their composites with phosphotungstic acid (PTA) were studied as heterogeneous acid catalysts in aldehyde-alcohol reactions exemplified by acetaldehyde-phenol (A-P) condensation and dimethylacetal formation from benzaldehyde and methanol (B-M reaction). The MIL-101 was synthesized solvothermically in water, and the MIL101/PTA composite materials were obtained by either impregnation of the already prepared MIL-101 porous matrix with phosphotungstic acid solution or by solvothermic treatment of aqueous mixtures of Cr(NO(3))(3), and terephthalic and phosphotungstic acids. The MIL101/PTA materials appeared to be effective catalysts for both A-P and B-M reactions occurring at room temperature, with half-lives ranging from 0.5 h (A-P) to 1.5-2 h (B-M) and turnover numbers over 600 for A-P and over 2900 for the B-M reaction, respectively. A synergistic effect of the strong acidic moieties (PTA) addition to mildly acidic Br?nsted and Lewis acid cites of the MIL-101 was observed with the MIL101/PTA composites. The ability of the PTA and MIL101/PTA materials to strongly absorb and condense acetaldehyde vapors was discovered, with the MIL101/PTA absorbing over 10-fold its dry weight of acetaldehyde condensate at room temperature. The acetaldehyde was converted rapidly to crotonaldehyde and higher-molecular-weight compounds while in contact with MIL-101 and MIL101/PTA materials. The stability of the MIL-101 and MIL101/PTA catalysts was assessed within four cycles of the 1-day alcohol-aldehyde reactions in terms of the overall catalyst recovery, PTA or Cr content, and reaction rate constants in each cycle. The loss of the catalyst over 4 cycles was approximately 10 wt % for all tested catalysts due to the incomplete recovery and minute dissolution of the components. The reaction rates in all cycles remained unchanged and the catalyst losses stopped after the third cycle. The developed MIL101/PTA composites appear to be feasible for industrial catalytic applications.     

Photocatalytic performance of CdS nanomaterials for photodegradation of organic azo dyes under artificial visible light and natural solar light irradiation

The CdS semiconductors have been prepared at low temperature via catalyst-free chemical precipitation method without using any surfactant or capping agent. Either water or ethylene glycol, as a solvent, provides spherical CdS nanostructures with a comparable size of 117–121 nm. The molar ratio of Cd/S plays an important role in determining phase structure, morphology and photocatalytic performance of the prepared CdS nanostructures. Increasing molar ratio of S^2? results in not only mixed cubic-hexagonal phases but also low photocatalytic performance. CdS nanoparticles with good dispersibility prepared at Cd/S molar ratio of 1:1 shows high photocatytic efficiency of 95% toward photodegradation of reactive red azo dye (RR141) under visible light irradiation up to 240 min. The degradation efficiency of CdS nanoparticles also reaches 48% under natural solar light irradiation for 80 min. This work demonstrates the promising potential of CdS nanomaterials as photocatalysts for environmental remediation.     

Rapid fabrication of three-dimensional porous films with biomimetic patterns by natural evaporation of amphiphilic polyacetylene solutions under ambient conditions

A simple process for fast fabrication of thin films with biomimetic morphological structures from a group of linear homopolymers is developed. Natural evaporation of tetrahydrofuran, chloroform, and hexane-dichloromethane solutions of poly(phenylacetylene)s that contain amino acid and ethylene glycol moieties under ambient conditions instantly produces three-dimensional porous films with structural patterns reminiscent of honeycombs and radiolarian shells. Morphological analysis by optical and electronic microscopy suggests that vesicles of the amphiphilic polymers serve as building blocks in the self-organization to the biomimetic structures.