Inert Gas Protection Research Articles

Removal of bentazon in water thorough a novel adsorbentprepared by IL@β-cyclodextrin/reduced graphene oxide/multiwall carbon nanotubes

A green, simple and catalyst-free ionic liquid@β-cyclodextrin-reduced grapheme oxide-multiwall carbon nanotubes (IL@β-CD-rGO-MWCNTs) was synthesized by hydrothermal reduction and chemical crosslinking without the protection of inert gases and the assistance of energy fields. With the characteristics of large specific surface area, good thermal stability, superior porous structure and rich functional groups, IL@β-CD-rGO-MWCNTs can be used as an effective adsorbent to rapidly remove bentazon from aqueous environments. Under optimal conditions (pH 6.0, solid–liquid ratio of 2:1 and no salt), the maximum adsorption capacity (qm) of IL@β-CD-rGO-MWCNTs to bentazon was 125.00 mg g−1 as corroborated by the Langmuir isotherm model at 40 °C, higher than that of the most commonly used bentazon adsorbent. Many molecular interactions, such as hydrogen bonding and π/π-π interaction, determine its adsorption capacity and selectivity. The adsorption kinetics and isotherm fit well with the pseudo-second-order kinetic model and Langmuir model, and the effective eluting adsorbent can be reused after treatment. The proposed strategy not only provides a valuable reference for the efficient synthesis of IL@β-CD-rGO-MWCNTs, but also provides a new strategy and ideas for the adsorption and removal of pollutants in water environments.

Magnetometric Characterization of Intermediates in the Solid-State Electrochemistry of Redox-Active Metal-Organic Frameworks.

Electrochemical energy storage has been a widely discussed application of redox-active metal-organic frameworks (MOFs) in the past 5 years. Although MOFs show outstanding performance in terms of gravimetric or areal capacitance and cyclic stability, unfortunately their electrochemical mechanisms are not well understood in most cases. Traditional spectroscopic techniques, such as X-ray photoelectron spectroscopy (XPS) and X-ray absorption fine structure (XAFS), have only provided vague and qualitative information about valence changes of certain elements, and the mechanisms proposed based on such information are often highly disputable. In this article, we report a series of standardized methods, including the fabrication of solid-state electrochemical cells, electrochemistry measurements, the disassembly of cells, the collection of MOF electrochemical intermediates, and physical measurements of the intermediates under the protection of inert gases. By using these methods for quantitatively clarifying the electronic and spin state evolution within a single electrochemical step of redox-active MOFs, one can provide clear insight into the nature of electrochemical energy storage mechanisms not only for MOFs, but also for all other materials with strongly correlated electronic structures.

Stability of self-encapsulated CsPbX3@PbX(OH)(X=Cl,Br) perovskite quantum dots in polar solvents

Inorganic halide perovskite quantum dots has excellent optical and photoelectric properties, so it has great potential in photovoltaic, photoelectric devices, display lighting, medical detection and other fields. However, its commercial application is hampered by its instability. In this paper, the perovskite quantum dots encapsulated by PbX (OH)(X = Cl,Br) can obtain hexahedral CsPbBr3@PbBr(OH), cube CsPbCl3@PbCl(OH) and spindle CsPbCl3@PbBr(OH) between hexahedron and cube. The core-shell encapsulation and interchange combination are realized. Before and after encapsulation, the color coordinates of CsPbX3 (X = Cl,Br) perovskite quantum dots basically did not change, no other crystal phases were found in the XRD lines, which indicatied that the PbX (OH) (X = Cl,Br) encapsulation layer did not change the crystal structure of perovskite quantum dots. PbX (OH) (X = Cl,Br) encapsulation layer plays the role of water-blocking layer and protective layer, which greatly improves the stability of CsPbX3 (X = Cl,Br) perovskite quantum dots in polar solvents. After encapsulation, the photoluminescence quantum yield (PLQY) and time-resolved photoluminescence decay performance of CsPbX3 (X = Cl,Br) perovskite quantum dots are greatly improved. The surface passivation and trap density of perovskite nanocrystals can be reduced by PbX (OH) (X = Cl,Br) wrapping, which extends the fluorescence life of CsPbX3 (X = Cl,Br) and improving the PL stability of perovskite structure. Room temperature (RT) crystallization method does not require inert gas protection, high temperature and high pressure conditions. It also has good repeatability, which provides a better alternative to hot injection. Meanwhile, the improvement of package stability provides a broader prospect for the application and promotion of lead halide perovskite.

One-step synthesis of nitrogen and sulfur co-doped hierarchical porous carbon derived from acesulfame potassium as a dual-function agent for supercapacitors and lithium‑sulfur batteries

Acesulfame potassium (AK) is an artificial sweetener that contains N and S functional groups in its organic moiety and is suitable as porous carbon precursor. In this study, AK derived carbon (AKC) was obtained via direct carbonization and in situ doping without additives under the dual conditions of inert gas protection and high temperatures. The obtained AKCs exhibited high porosity structure with a specific surface area of 2043 m2 g−1 and 3.22 wt% N and 8.61 wt% S dual heteroatom doping. When applied to the supercapacitor electrode, the AKC ensured a high capacitance of 264 F g−1 at 0.5 A g−1, which maintained 86.1 % of the initial capacitance after 5000 cycles at 5 A g−1, and an ultra-high energy density of 16.3 Wh kg−1 in a full cell device. By analyzing its application in the lithium‑sulfur battery cathode, the S-loaded AKC exhibited a high capacity of 1075 mAh g−1 at 0.1C, and 490.5 mAh g−1 after 150 cycles with 66.5 % of capacity retention. The excellent performance of AKC can be attributed to its high specific surface area, pore structure, and sulfur and nitrogen co-doping combine effect. Overall, AKCs exhibited excellent electrochemical performances, thereby proposing a new synthetic strategy of preparing dual heteroatom doped porous carbon for high-performance electrode materials through a single precursor and low-cost perspective.

Iron-Catalyzed Deoxynitrogenation of Carboxylic Acids with Cyanamides to Access Nitriles.

Efficient strategies to access nitriles from common organic functionalities are highly important, given their significance in synthetic and medicinal chemistry. Although the direct transformation of carboxylic acids to nitriles have been explored for decades, there is few general and practical protocol to access nitriles from carboxylic acid precursors. Herein, an iron-catalyzed deoxynitrogenaton strategy to convert carboxylic acids into nitriles is described. This method utilizes a cyanamide as the recyclable nitrogen donor and deoxygenating reagent, operates broadly across aryl, alkenyl, and alkyl carboxylic acids, and features an easy setup without inert gas protection. The synthetic value of this method is demonstrated by application in late-stage modification of drug molecules, synthesis of a pharmaceutical structure, and scaleup reactions and downstream derivatizations.

TiO2/C aerogel composites as high-performance electrode materials for supercapacitors

[Formula: see text]/C aerogel composites are primarily composed of resorcinol-formaldehyde (RF) and low-cost commercial titanium dioxide nanoparticles. These composites are synthesized through a simple process of freeze-drying and high-temperature carbonization under inert gas protection. [Formula: see text] nanoparticles in the [Formula: see text]/C aerogel composites produce partial oxygen vacancies by high-temperature treatment under anoxic conditions which is beneficial to increase the carrier density of the material. Electrochemical characterizations confirm the excellent specific capacitance, which reaches a maximum of 250 F [Formula: see text] at a current density of 0.2 A [Formula: see text]. Moreover, after 5000 charge/discharge cycles at a current density of 10 A [Formula: see text], capacitance retention can be up to 98% or more. These properties are attributed to a synergistic effect of electrical double layer capacitance and pseudo-capacitance.

Low-temperature molten salt synthesis and catalytic mechanism of CoS2/NC as an advanced bifunctional electrocatalyst.

The development of productive and sustainable bifunctional electrocatalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) plays an important role in the commercial evolution of metal-air batteries. In this paper, a low-temperature molten salt template method was adopted to synthesize the composite of CoS2 and nitrogen-doped carbon (CoS2/NC) without the protection of inert gas. The structural characterization studies show that the specific surface area (SSA) and crystal growth kinetics are increased and effectively improved, respectively, by the composite of CoS2 and NC. The as-synthesized CoS2/NC composite demonstrates outstanding bifunctional catalytic activity in alkaline electrolytes and exhibits a half-wave potential (E1/2) of 0.854 V (vs. RHE) and an overpotential of only 220 mV for the OER at a current density of 10 mA cm-2 (η10). Simultaneously, CoS2/NC also exhibits excellent electrochemical stability. Additionally, density functional theory (DFT) calculations have manifested that the synergistic effect of CoS2 and NC results in a remarkable enhancement in the bifunctional catalytic performance of the composite materials. This study offers a new pathway and theoretical guidance for the fabrication of efficient bifunctional electrocatalysts.

Cleaner Dyeing Technology for Denim Fabrics with Excellent Utilization of Indigo Based on Inert Gas Protection

Cleaner Dyeing Technology for Denim Fabrics with Excellent Utilization of Indigo Based on Inert Gas Protection

Ex-situ EPR approach to explore the electrochemical behaviour of Arylboron-Linked conjugated microporous polymer cathode

Electron paramagnetic resonance (EPR) spectroscopy is an important technique to probe the evolution of organic radicals during battery charging and discharging. Herein, we co-polymerize arylboron units and anthraquinone groups into a new organic electrode material, B-AQ, which has both the material characteristics of a conjugated microporous polymer and the special electronic properties of arylboron units and exhibits excellent thermodynamic stability and electrochemical properties. The experimental results show that the B-AQ cathode has fast charging/discharging capability at high current density and remarkable long cycle performance with very low capacity decay of 0.004 % per cycle over 2000 cycles. Adequate EPR method reveals the charging and discharging mechanism of the B-AQ electrode, i.e., the anthraquinone units gradually undergo anthraquinone radical species and enol lithium salt intermediates. In addition, comparative test studies show that inert gas protection of the discharge products in ex-situ EPR tests is necessary. This work will expand the research and application direction of boron-containing polymers and also provides an effective way to explore the reaction processes in organic lithium-ion batteries.

Biodegradable and Light-Responsive Polymeric Nanoparticles for Environmentally Safe Herbicide Delivery.

The low utilization efficiency of pesticides exerts an adverse impact on the environment and human health. Polymer-related controlled-release nanosized pesticide systems provide a promising and efficient way to overcome the problem. In this work, a biodegradable and light-responsive amphiphilic polymer was synthesized via 1,1,3,3-tetramethylguanidine-promoted polyesterification under mild conditions (low temperature, no vacuum, and no inert gas protection). We used this polymer to fabricate a light-triggered controlled-release nanosized pesticide system. The herbicide, 2,4-dichlorophenoxyacetic acid (2,4-D), was selected as a model drug to show its potential as a controlled-release pesticide system. It was found that the 2,4-D-loaded polymeric nanoparticles were stable without the treatment of UV, while the release rate of 2,4-D from the nanoparticles gradually increased after treatment with UV light. Pot trial showed that the 2,4-D-loaded polymer nanoparticles showed a good herbicidal effect. Finally, toxicity studies suggested that the polymer can reduce toxicity to nontarget organisms.

One-step synthesis of polymer based N-doped porous carbon with enriched nitrogen content and its enhanced electrochemical properties in supercapacitors

N-doped porous carbon (N-PC) is considered as a promising candidate for electrochemical energy storage. However, the complicated multistep process is the biggest bottleneck. Here, a facile one-step strategy was employed to fabricate the N-doped porous carbon via the co-pyrolysis of urea and poly(acrylic acid-co-maleic acid) sodium salt (PAMS) without the protection of inert gas at 550 °C. When the mass ratio of urea to PAMS is 4:1, the microstructure and electrochemical properties of the as-prepared sample (N-4PC) are obviously improved compared with that of the direct carbonization of PAMS (PC). N-4PC presents salient peculiarities with much more mesopores, higher specific surface area of 181.5 m2 g−1 far more than PC (23.6 m2 g−1), and its nitrogen content is up to 10.61 at. %. In a three-electrode configuration using 6 M KOH, owing to the synergistic effect of pyridinic N, pyrrolic N and graphitic N atoms, N-4PC shows an outstanding specific capacity of 210 F g−1 far more than that of PC (93 F g−1) at 1 A g−1, and a significant capacity retention rate of 79 % much higher than PC (47 %) at 20 A g−1. Furthermore, the symmetric supercapacitor fabricated by N-4PC delivers an attractive specific capacitance of 140 F g−1 at 1 A g −1, and 4.9 Wh kg−1 energy density when the power density is 265 W kg−1 in 6 M KOH. The equipment achieves superior cycle stability with capacity retention of 97 % after 7000 cycles at 1 A g−1. Additionally, N-4PC also achieves great energy densities of 6.7 Wh kg−1 at the power density of 372.3 W kg−1 in 1 M H2SO4 and 12.5 Wh kg−1 at the power density of 521.5 W kg−1 in 1 M Li2SO4. The fabricated nitrogen-doped porous carbon material has a great potential application prospect in energy storage equipment.

Metal‐and Base‐Free Oxidative Cleavage of C(O)−C Bond in Ketones to Access Esters

AbstractA novel strategy to selective cleavage and esterification of C(CO)−C bonds is described. The efficient approach showed a prominent merit compared to previously reported systems, without high temperature, high pressure, inert gas protection, and transition‐metal free. Meanwhile, a rational C−C bond cleavage possible mechanism is proposed by the control experiments.

Reduced pressure laser weld comparison to electron beam welds in Ti-6Al-4 V

Reduced pressure laser welds were made using a 6-kW commercial fiber-laser system on Ti-6Al-4 V and compared to electron beam welds of the same beam diameters as measured by beam diagnostics. The laser welds showed keyhole characteristics under easily achievable mechanical pumped vacuum levels of 1 mbar pressure that nearly matched the electron beam weld penetrations made at 9 × 10–5 mbar vacuum. Ti-6Al-4 V alloys were used to represent refractory metals such as vanadium, tantalum, zirconium, or molybdenum that require vacuum or highly protective inert gas protection systems to prevent adverse interactions with air and can be difficult to weld under non-vacuum conditions. Results show that laser weld depths of 20 mm with aspect ratios of 17:1 can be made under what appears to be stable keyhole behavior as the result of reduced pressure. The effect of fiber diameter was examined using 0.1-, 0.2-, and 0.3-mm fibers, showing that small spot sizes can easily be achieved at long focal length lenses of 400 and 500 mm. The 0.1- and 0.2-mm fibers produced keyhole welds with minimal amounts of porosity, which was only present at 2 kW or higher, while the 0.3-mm fiber produced keyhole welds with more rounded roots that were porosity free as shown by radiography up to the maximum power of 6 kW. Correlations between weld depth and processing conditions are presented for the reduced pressure laser. These results are directly compared to electron beam welds, facilitating design of future reduced pressure laser systems targeted for deep weld penetrations historically developed for electron beams.

The catalytic effect of RuM-C catalyst attached to carbon- based support for hydrogen evolution reaction

The potential of converting traditional biomass into low-cost HER catalysts has broad application prospects. In this paper, fungus is used as a carbon-based carrier. The bimetallic catalyst RuM-C (M = V, Mo, W, Zn, Cu) was synthesized under inert gas protection at high temperature. The order of electrocatalytic activity is RuV-C > RuZn-C > RuW-C > RuMo-C > Ru-C > RuCu-C > BF-C, which indicates that RuV-C exhibits excellent HER activity. Due to its irregular sheet structure, the specific surface area of the catalyst is increased. Impressively, it exhibits extremely high catalytic activity for HER in 1 M KOH due to favorable kinetics and excellent specific activity. Consequently, the prepared RuV-C exhibited excellent and stable HER activity compared Ru-C with a low overpotential of 65.78 mV at the current densities of 10 mA cm−2 and Tafel slope of 45.26 mV dec−1. The potential only decreased by 88 mV after 24 h of continuous testing, which indicates that the catalyst has outstanding stability. This work will provide positive inspiration for the promotion of a new Ru-based biomass HER electrocatalyst.

A facile one-pot synthesis of ionic liquid@porous organic frameworks for rapid high-capacity removal of heavy metal ions, pesticides and aflatoxin from two non-food bioactive products

Without inert gas protection and extra assistance by energy field, a green, facile, and catalyst-free strategy to synthesize ionic liquid@porous organic frameworks (IL@POFs) with high efficiency was developed for the first time. Besides, they have high specific surface area, stability and sustainability. As the brutal facts, many industrial crops are easily polluted and then cause safety risks. Among above IL@POFs, 1-butyl-3-methylimidazolium proline salt@porous organic framework ([C4mim][L-pro]@POF) exhibits rapid removal performance for typical heavy metal ions from Poria cocos (removing 100% Pb2+ within 5 min; 207.47 mg/g for Pb2+ and 62.85 mg/g for Cu2+). The separation mechanisms are coordination, accompanied by ion exchange and electrostatic interaction. Moreover, 1-butyl-3-methylimidazolium hexafluorophosphate@porous organic framework ([C4mim][PF6]@POF) could remove 85% triazophos and 93% aflatoxin B1 (AFB1) effectively from Radices trichosanthis within 5 min, and multiple intermolecular interactions contribute to its adsorption capacity and selectivity. Above sorbents can be reused after effective elution. The proposed strategy not only provides valuable reference for the high-efficient synthesis of IL@POFs but also opens up a new pathway to recycling contaminated industrial crops.

One-pot synthesis of mesoporous silicas supported Cu single-atom and CuO nanoparticles for peroxymonosulfate-activated degradation of tetracycline over a wide pH range

Peroxymonosulfate activated heterogeneous Fenton-like catalytic reactions are promising in degradation of recalcitrant pollutants. Mesoporous silicas supported high-dispersion Cu species, as a kind of conventional heterogeneous catalysts for extensive applications, are rarely studied for their degradation efficiency in peroxymonosulfate-triggered reactions. In this work, one-pot incorporation method was employed to generate simultaneously Cu single-atom, Cu nanoparticles in mesoporous silicas (like the sample of Cu/Si-3 with 0.68 wt% of Cu) using sodium copper chlorophyllin as Cu source by calcining directly in air atmosphere. Several characterizations confirm the coexistence of Cu single-atom, Cu nanoparticles and mesopore with uniform size distribution. Activated by peroxymonosulfate, Cu/Si-3 was found to be efficient in degradation of tetracycline throughout a wide pH range of 2–11. The radicals of S O 4 g − , ⋅ O H and O 1 2 played their role in the degradation reaction. The underlying catalytic mechanism of the Fenton-like reaction was speculated on the basis of analysis of reactive oxygen species. This work has important implication in reasonable design and fabrication of catalysts with high-dispersion metal and controllable synthesis of functional mesoporous materials, as well as in proper disposal of recalcitrant pollutants including tetracycline. • Composite of Cu single-atom and CuO nanoparticles simultaneously generated by one-pot synthesis under air atmosphere. • Successful preparation of mesoporous materials with uniform size distribution. • Cu single-atom catalysts obtained by calcination without protection of inert gas. • The obtained highly dispersed Cu species favourable in degradation of tetracycline. • The catalyst's wide working pH window of 2–11.

Mechanochemical synthesis of half‐sandwich iridium/rhodium complexes with 8‐hydroxyquinoline derivatives ligands

AbstractMechanochemistry provides a rapid, efficient route to half‐sandwich iridium and rhodium complexes from [MCp*(μ‐Cl)Cl]2 (M = Ir, Rh) and 8‐hydroxyquinoline‐2‐carbaldehyde without the need for Schlenk manipulation, inert gas protection, or dry solvents. Furthermore, post‐synthetic modification of the half‐sandwich metal complexes has been carried out via a mechanochemical Wittig reaction between half‐sandwich metal complex and phosphorus ylide. All complexes were fully characterized by 1H and 13C NMR spectra, infrared spectroscopy, mass spectrometry, and single‐crystal X‐ray diffraction method. The half‐sandwich rhodium complexes exhibited high catalytic activity towards the amide synthesis between aldehyde and hydroxylamine hydrochloride (NH2OH·HCl) with a broad functional group tolerance.

Fluorine‐Free Nanoporous Low‐k Dielectric Film Covalently Grafted on Si via Aryldiazonium Chemistry

AbstractFluorine‐free nanoporous low‐k dielectric film containing polyhedral oligomeric silsesquioxanes (POSS) cage nanostructure is covalently grafted onto a p‐Si(100) surface via aryldiazonium chemistry, in an open environment without any inert gas protection. The method is based on two‐step reduction of aryldiazonium salts. First, 4‐nitrobenzene diazonium tetrafluoroborate (NBD) is reduced and a polynitrophenyl (PNP) passivation layer is formed on the p‐Si(100) surface, in an aqueous media with hydrofluoric acid being added. Second, NBD is reduced by electrons provided by external pulse power supply, and initiates octavinylsilsesquioxane polymerizing to form the film, which is composed of PNP and massive POSS cage, leading to a low k value. The average dielectric constant of the film is 2.12 at the range of 600 to 1700 nm wavelength, much lower than some low‐k materials reported by recent literature and traditional materials. The prepared films completely cover the Si substrate and are compact and thickness controllable. In particular, the k value can be controlled though the concentration of NBD. The low‐k properties imply they will be suitable to be utilized as high‐performance dielectric materials in future higher frequency communication field.

Mechanism of Microwave Activation on Molybdenite.

The effect of microwave activation on the properties of oxidation roasting for molybdenite was investigated under the protection of inert gas, and the specific surface area, the oxidation properties, lattice constant, microstructure, and shape of molybdenite were analyzed and characterized by a laser particle size analyzer, thermogravimetry (TG), X-ray diffractometry (XRD) and scanning electron microscopy (SEM). The results show that microwave activation could effectively reduce the residual amount of sulfur in the molybdenum calcine and decrease the average particle size of molybdenite while increasing the specific surface area of molybdenite. On increasing the microwave activation power, the crystal cell volume and grain size of MoS2 reduced, and the microstrain increased slightly. At the same time, the surface shape of molybdenite became looser, but the layered structure is not changed. In addition, the oxidation property changed significantly; microwave activation promoted the oxidation reaction of molybdenite above 538 °C, and the rate of weight loss increased from 6.177% to 7.718% at 620 °C.

Li-ion storage properties of two-dimensional titanium-carbide synthesized via fast one-pot method in air atmosphere

Structural bidimensional transition-metal carbides and/or nitrides (MXenes) have drawn the attention of the material science research community thanks to their unique physical-chemical properties. However, a facile and cost-effective synthesis of MXenes has not yet been reported. Here, using elemental precursors, we report a method for MXene synthesis via titanium aluminium carbide formation and subsequent in situ etching in one molten salt pot. The molten salts act as the reaction medium and prevent the oxidation of the reactants during the high-temperature synthesis process, thus enabling the synthesis of MXenes in an air environment without using inert gas protection. Cl-terminated Ti3C2Tx and Ti2CTx MXenes are prepared using this one-pot synthetic method, where the in situ etching step at 700 °C requires only approximately 10 mins. Furthermore, when used as an active material for nonaqueous Li-ion storage in a half-cell configuration, the obtained Ti2CTx MXene exhibits lithiation capacity values of approximately 280 mAh g−1 and 160 mAh g−1 at specific currents of 0.1 A g−1 and 2 A g−1, respectively.