High-efficiency Synthesis Research Articles

High-efficiency synthesis of large-area monolayer WS2 crystals on SiO2/Si substrate via NaCl-assisted atmospheric pressure chemical vapor deposition

Synthesis of monolayer WS2 crystals on SiO2/Si substrate has attracted interests due to the advantage of fabrication of field effect transistor without WS2 transfer process. Although substantial efforts have been achieved in recent years, controllable synthesis of uniform and large-area monolayer WS2 crystals on SiO2/Si substrate is still challenging. Herein, we report an elegant method to synthesize monolayer WS2 crystals on SiO2/Si substrate by using NaCl as a growth promoter in one semi-sealed quartz tube. It is found that triangular monolayer WS2 with edge lengths ranged from 10 to 460 μm can be readily synthesized within 5 min of growth by adjusting the growth temperature and weight ratio of NaCl and WO3. The Raman mapping results indicate that the as-synthesized WS2 crystals exhibit homogeneous distributions of the crystallinity, electron doping and residual strain across the entire triangular domains regardless of their dimensions. However, the smaller WS2 crystals exhibit a higher electron doping and less residual strain compared to the larger one obtained under the same growth conditions. Importantly, the amount of WO3 used in this study is three orders lower than the commonly reported one and the semi-sealed quartz tube can be reused more than 50 times after mildly cleaning.

Ultrafast green ion-exchange and short lifetime of efficient (NH4)3SiF7:Mn4+ millimeter-sized single crystal for backlight displays

Since narrowband red emission and broadband blue excitation, Mn4+-activated fluorides show great promise for white lighting and backlit displays. However, it is a challenge to achieve these phosphors with integrations of high absorption efficiency (AE > 60%), short lifetime (<5 ms) and green synthesis. Here, we report an efficient (AE ∼60%), fast decaying (4.6 ms) red emission in novel double salt (NH4)3SiF7:Mn4+ millimeter-sized single crystal via green H2O-phase volatilization and ultrafast ion-exchange association. Interestingly, its ultrafast ion-exchange as touching in crystal mainly root in the strong ionicity and thin prismatic shape of host evidenced by contrastive synthesis of (NH4)2SiF6:Mn4+ millimeter-sized single crystal. Refined contrasts into their crystal structure, luminescence behavior and Mn4+ distribution disclose that (NH4)3SiF7:Mn4+ presents higher AE and much weaker quenching in Mn4+ concentration and thermal impact over (NH4)2SiF6:Mn4+ due to its Mn4+ even heavy distribution and larger transition probability. It also could be deduced that the intrinsic relatively loose framework of (NH4)3SiF7 might favor the short lifetime of Mn4+ emission. Using (NH4)3SiF7:Mn4+ as red component realizes a W-LED with ultrawide color gamut of 122.8% NTSC. Our findings probably propose a green and simple strategy for designing fast decaying, highly efficient, large-sized single crystal Mn4+-doped fluorides for W-LED applications.

An in vitro study on hexavalent chromium [Cr(VI)] remediation using iron oxide nanoparticles based beads

This study focused on a kind of high efficiency and low cost iron oxide nanoparticles (IONPs) synthesis and loaded with sodium alginate beads used for remediation of hexavalent chromium [Cr (VI)] contaminated water. Due to high toxicity and mobility of Cr (VI) is considered to be a toxic pollutant. The synthesized IONPs were characterized by UV–vis and FTIR spectroscopy analysis. The IONPs loaded alginate beads was characterized and its chromium remediation property was evaluated by diphenyl carbazide assay and batch experiment was performed at different pH ranges (pH 1–7). The present study revealed that Cr (VI) is effectively reduced by IONPs loaded alginate beads nearly 90 % at pH 2.5 with the average size of 2 mm and the stability of the interacted particle observed around 60 min at 500 rpm. Finally it was demonstrated that, a cost effective method for the in situ remediation of Cr (VI) was achieved by IONPs loaded alginate beads.

Heterostructure Co3O4@NiWO4 nanocone arrays with enriched active area for efficient hydrogen evolution reaction

Low cost and efficient electrocatalysts are extremely attractive for hydrogen evolution reaction (HER). Here, three-dimensional hybrid Co3O4@NiWO4 nanocone arrays are firstly constructed by a simple and effective strategy on nickel foam. Due to the open space and enriched active areas provided by the special nanocone arrays heterostructure, Co3O4@NiWO4 exhibits excellent HER performance. The overpotential is only 70 mV at 10 mA cm−2, and it also has good durability under alkaline conditions. This research provides a guiding strategy for the synthesis of high-efficiency and stable electrocatalyst for the HER by enriched active areas.

High-Efficiency Synthesis of 5-Hydroxymethylfurfural from Fructose over Highly Sulfonated Organocatalyst

The high-efficiency conversion of fructose to 5-hydroxymethylfurfural (HMF) with approving yields is challenging in biorefinery. In this work, we develop an efficient method of preparing HMF from f...

Industry-oriented Fe-based amorphous soft magnetic composites with SiO2-coated layer by one-pot high-efficient synthesis method

A new one-pot highly efficient synthesis method implemented using an industry-oriented roboticized coating device was designed and developed for obtaining high quality SiO2-coating on the surface of commrercial Fe78Si13B9 (FeSiB) amorphous flaky powder at the room temperature. Hereinto, the conventional instilling method was modified as directly pouring the ultra-diluted precursor by anhydrous ethanol into the reaction mixture, favorable for both simple operation and shortening the total manufacture time to 1.9 h (including the drying time of about 0.7 h). Comparison and analysis on the soft magnetic properties of the FeSiB amorphous powder cores insulated using different precursor concentration within the range of 0 ~ 0.25 ml/g were investigated in detail. SEM, EDS, and FTIR were employed to characterize the core-shell structure of magnetic powders. The increment of pinning sites induced by the raising precursor concentration can cause a reduction in effective permeability, while result in the increases of hysteresis loss and excess loss. The eddy current loss contributes only about 13.5% ~ 18.1% of total core loss for the coated powder cores under the TEOS concentration over 0.09 ml/g, indicating that the corresponding magnetic composites have a good electro-insulating layer. This work offered a referable idea for efficiently coating other inorganic insulations on the magnetic powders within different shapes.

Adsorption of pharmaceuticals and personal care products by deep eutectic solvents-regulated magnetic metal-organic framework adsorbents: Performance and mechanism

The ecological and human health threats brought by emerging pollutants are increasingly serious. Development of efficient removal methods is urgent. Herein, seven deep eutectic solvents (DESs) composed by quaternary ammonium salts and lactic acid or glycolic acid were synthesized and used to regulate magnetic (Fe3O4) metal organic framework (MUiO-66-NH2) composites. The obtained nanoparticles (named as DES-MUiO-66-NH2) were used as adsorbents to adsorb pharmaceuticals and personal care products (PPCPs). Langmuir isotherm model and pseudo-second-order kinetics model were suitable to analyze the adsorption process of DES-MUiO-66-NH2 to PPCPs, indicated that the adsorption of PPCPs was chemisorption on homogeneous surface of DES-MUiO-66-NH2 adsorbents. Under the optimal conditions, the adsorption capacity of DES-MUiO-66-NH2 toward ofloxacin and mefenamic acid reached up to 97.60 and 79.22 mg/g, respectively. Mechanism exploration indicated that DES-MUiO-66-NH2 selectively adsorbed PPCPs through electrostatic interaction, chelation, π-π stacking, hydrophobic interaction and hydrogen bonding. Density functional theory proved the chelation through theoretical calculation. Selective experiments manifested that the structures of DESs directly determined the specificity of DES-MUiO-66-NH2 for different PPCPs, and the investigation of structure–activity relationship provided new ideas for designing efficient tailor-made adsorbents for PPCPs. The proposed PPCPs removal approach focused on the guiding role of DESs in selective adsorption. And this green DESs regulation idea provided more options for the synthesis of high-efficiency and functional adsorbents for emerging pollutants.

A Set of phenyl sulfonate metal coordination complexes triggered Biginelli reaction for the high efficient synthesis of 3,4‐dihydropyrimidin‐2(1H)‐ones under solvent‐free conditions

Three new metal coordination complexes, namely, [Co (DPE)(H2O)4](DPE)(BS)2 (1), [Co (DPE)2(H2O)4](ABS)2 (2), [Co (DPE)(H2O)4](MBS)2(CH3OH)2 (3) [DPE = (E)‐1,2‐di (pyridin‐4‐yl) ethene, BS = phenyl sulfonic acid, ABS = p‐aminobenzene sulfonic acid, MBS = p‐methylbenzene sulfonic acid] were obtained under hydrothermal conditions. Complexes 1‐3 were structurally characterized by X‐ray single‐crystal diffraction, powder X‐ray diffraction and IR. Complexes 1 and 3 exhibit a one‐dimensional chain structure, and complex 2 does a zero‐dimensional one. These three complexes further generate a three‐dimensional supramolecular architecture via strong hydrogen bonding interactions and packing interactions. These three metal coordination complexes show high catalytic performance for green synthesis of a variety of 3,4‐dihydropyrimidin‐2(1H)‐ones through the Biginelli reactions, which show several advantages such as excellent yields, short reaction times, eco‐friendly synthesis conditions, and simple isolated workup procedure. Interestingly, the order of catalytic activities for these catalysts is the following: 3&gt;1&gt;2, which can be ascribed to the acidities and hydrophobic interactions of phenyl sulfonate groups.

Specific role of aluminum site on the activation of carbonyl groups of methyl levulinate over Al(OiPr)3 for γ-valerolactone production

The high-efficiency synthesis of biofuel γ-valerolactone (GVL) from biomass-derived levulinates is a challenging task. The Meerwein-Ponndorf-Verley (MPV) reduction with its extraordinary chemoselectivity is advantageous for the hydrogenation process, compared to the molecular-hydrogen-based process using noble metal catalysts. Therefore, we used a classical Al-based isopropoxide to catalyze transfer hydrogenation (CHT) of methyl levulinate (ML) to GVL. A high yield of GVL up to 97.6% could be achieved using 2-proponal as the H-donor and solvent under mild conditions (150 °C, 30 min). Besides, three reaction stages were observed in the conversion, including transesterification, hydrogenation and cyclization. LC/MS analysis and the density functional theory (DFT) caculations revealed that Al atom of Al(OiPr)3 as the electron transfer center activated ester carbonyl of the substrate via four-membered transition states before activating the ketone carbonyl, resulting in the occurrence of transesterification prior to the hydrogenation. In addition, 2-propanol as proton transfer carrier assisting the cyclization process was proved to be the lowest-energy pathway. Our work shed light on the role of Al (OiPr)3 in the MPV reduction of ML, providing a comprehensive understanding on the metal alkoxide catalysis mechanism for GVL production.

High-efficiency synthesis of Co, N-doped carbon nanocages by ball milling-hard template method as an active catalyst for oxygen reduction reaction

A facile and scalable method is developed for the high-efficiency synthesis of Co, N-doped carbon nanocages catalyst for the oxygen reduction reaction (ORR). During the synthesis, the precursors are uniformly distributed on the surface of potassium chloride (KCl) by high-energy ball milling. As evidenced, the N and Co elements are successfully doped and distributed uniformly on the surface of carbon nanocages. Owing to the distinctive nanocage architecture and the synergistic effects of Co, N and Co-NX coordination, the obtained Co, N–CNC-800 shows efficient ORR catalytic activity with an onset potential of 0.924 V (vs. RHE), and the number of electron transfer (n) is approximately 3.4. Furthermore, its stability and methanol tolerance are far superior to those of commercial 40% Pt/C. This simple and universal synthesis strategy is expected to be widely applied in the preparation of other heteroatom-doped carbon nanocages as catalysts in hydrogen fuel cells.

High-Efficiency Synthesis and Properties of Latent Pigment Red 272DPP-BOC by Microwave Irradiation

A high-efficiency synthesis method for a latent pigment of red pigment diketo-pyrrolo-pyrrole (Pig. Red 272:272DPP), which is important as a functional organic pigment, was investigated, and the investigation results revealed that irradiation of microwaves (MWs) for several seconds to 272 DPP in NMP (N-methyl-2-pyrrolidone) solvent yielded DPP latent pigment (272DPP-BOC) at a high yield of 86.2%. Two kinds of latent-pigment crystals, namely, red and yellow, were obtained by recrystallization, and it was found that the fluorescence-emission properties of the two kinds differ significantly. Single-crystal X-ray structural analysis showed that the difference in the fluorescence-emission properties of the two types is derived from the difference in their crystal structures.

高效荧光碳点的制备及其对金属离子的检测研究

高效荧光碳点的制备及其对金属离子的检测研究

High Efficiency Synthesis of the Tetrasccharide Repeating Unit in Azospirillum brasilense Strains Sp246 Based on Silica Gel Supported Perchloric Acid (HClO4-SiO2)

High Efficiency Synthesis of the Tetrasccharide Repeating Unit in <i>Azospirillum brasilense</i> Strains Sp246 Based on Silica Gel Supported Perchloric Acid (HClO₄-SiO₂)

In-situ stirring assisted hydrothermal synthesis of W-doped VO2 (M) nanorods with improved doping efficiency and mid-infrared switching property

Vanadium dioxide (VO2) is considered to be one of the most competitive thermochromic materials, due to its semiconductor-metal phase transition characteristics. And the doping of tungsten (W) into the lattice of VO2 can significantly reduce the phase transition temperature to near room temperature. However, the reduction efficiency dependent on doping amount is quite different in previous reports. In this work, we proposed an in-situ stirring assisted hydrothermal to synthesize W-doped VO2 nanorods with improved doping efficiency. The effects of in-situ stirring during the hydrothermal synthesis on phase composition, sample morphology, and phase-transition temperature of VO2 with different W doping amounts were studied systematically. The phase transition temperature reduction efficiency of W-doped VO2 prepared by hydrothermal synthesis without in-situ stirring was at % W. By contrast, the phase transition temperature of W-doped VO2 prepared by in-situ stirring hydrothermal synthesis was depressed as much as 24.55 °C/at % W when W/V ranged in 0.75–2.0 at %. Further research found that the phase transition temperature of W-doped VO2 (M) could be simply tuned by changing the in-situ stirring time. Then, the 1 at% W-doped VO2 (M) (with phase transition temperature of around 41.5 °C) nanorods and acrylic resin were mixed to prepare VO2 composite film. It exhibited suitable infrared transmission (>60%) and excellent mid-infrared transmission switching performance (23.77%). This work proposed an in-situ stirring hydrothermal method for high efficiency synthesis of W-doped VO2 (M) and provided significant insights for its application in thermochromic windows.

Vanadium Nitride Nanoparticles as Anode Material for Lithium Ion Hybrid Capacitor Applications

A high production efficiency synthesis method was used to produce a stacked vanadium nitride nanoparticle structure with an inexpensive raw material as an anode material and high surface area polystyrene was used the cathode material for lithium ion hybrid capacitors. The Li-HCs cell displayed an excellent specific capacitance of 64.2 F·g-1 at a current density of 0.25 A·g-1 and a wide potential window of 0.01 to 3.5 V. Furthermore, the device exhibited a high energy density of 109.3 W·h·kg-1 at a power density of 512.3 W·kg-1 and retained an energy density of 69.2 W·h·kg-1 at a high power density of 3 498.9 W·kg-1 at 2 A·g-1. Due to the short synthesis time and simple raw materials, this method is suitable for industrial production.

Prepared LiFePO4 cathode at mild and air atmosphere conditions to real low-energy-consumption synthesis material

Abstract As an important cathode in Li-ion batteries, lithium iron phosphate (LiFePO4) is widely used in electric vehicle. The production of LiFePO4 require very high harsh conditions, such as high-temperature and gas protection. In order to decease preparation condition, the LiFePO4 material was synthesized below 300 °C to reduce energy consumption. The high-regular iron phosphate (FePO4) was prepared by hydrothermal synthesis and room temperature. The results show that the synthesized LiFePO4 exhibits the stable cyclicity. And the initial capacity reaches 115 mAh·g−1. Though, the ideal and enlightening material provides the high-efficient synthesis method for the low-cost production of LiFePO4 cathode materials.

The China National GeneBank─owned by all, completed by all and shared by all

Genetic resources are important national strategic resources. Their preservation, protection and rational utilization form a solid foundation to guarantee national security and to build national competitiveness for the future. Due to a relatively late starting point, China is actively catching up with global peers in storing genetic samples and data. In view of this, in 2011 China approved a plan to build its first nation-level comprehensive gene bank, the China National GeneBank (CNGB), and entrusted BGI-Research to implement its construction and operation. It is China's first gene bank for "reading, writing and storing" bioresources. In this paper, we summarize the development of influential platforms at home and abroad, and focus on CNGB's position, mission, and its structure of "Three Banks and Two Platforms". CNGB launched its official operation in September 2016 and aims to develop a world-class, non-profit and strategic platform that supports science and technology development. It has built capacities to store tens of millions of traceable samples and to analyze handreds of thousanda of WGS each year. It has also set up China's first Pb-level digitalization platform and a high-efficient synthesis platform with a production rate of ten million bases per year. Based on such capacities, CNGB has established its open sharing mechanism for biological samples and data, provided public platform services for life science research, and achieved initial results in supporting innovation and development of the bio-industry.

Low-Temperature High-Efficiency Preparation of TiB2 Micro-Platelets via Boro/Carbothermal Reduction in Microwave Heated Molten Salt.

A molten-salt and microwave co-facilitated boro/carbothermal reduction methodology was developed for low temperature high-efficiency synthesis of TiB2 powders. By using relatively inexpensive titanium oxide (TiO2), boron carbide (B4C) and amorphous carbon (C) as raw materials, single-phase TiB2 powders were prepared after 60 min at as low as 1150 °C or after only 20 min at 1200 °C. Such synthesis conditions were remarkably milder than those required by the conventional reduction routes using the identical reducing agent. As-synthesized TiB2 powders exhibited single-crystalline nature and well-grown hexagonal-platelet-like morphology. The achievement of low temperature high-efficiency preparation of high-quality TiB2 microplatelets in the present work was mainly attributable to the synergistic effects of molten-salt medium and microwave heating.

Nano-ZnO functionalized biochar as a superhydrophobic biosorbent for selective recovery of low-concentration Re(VII) from strong acidic solutions

A novel nano-ZnO functionalized biochar with superhydrophobic surface was successfully synthesized and tested for selective recovery of Re(VII) anions in strong acidic solutions. The as-synthesized biochar was characterized by XRD, XPS, FT-IR, EDX, TEM, STEM-HAADF, SAXS, N2 adsorption-desorption isotherm and water contact angle measurements. The characterization results revealed that the functionalized biochar was composed of highly dispersed ZnO nanoparticles bound to biochar matrix and displayed superhydrophobicity with water contact angle of about 151–156°. Because of the synergistic effect of surface superhydrophobicity and metal affinity, the new biochar exhibited excellent selectivity and high efficiency to Re(VII) in the presence of various competing ions. Adsorption mechanism exploration found that inner-sphere complexation on homogeneous surface would be the dominant interaction, while liquid film diffusion was considered as the rate-controlling step in the sorption process. Due to its excellent selectivity, high efficiency and easy synthesis process, the obtained superhydrophobic biosorbent is ideal candidate for Re(VII) recovery from copper smelting acidic wastewater.

Improving biocatalysis of cefaclor with penicillin acylase immobilized on magnetic nanocrystalline cellulose in deep eutectic solvent based co-solvent

Deep eutectic solvent (DES), has been considered as a new type of green solvent applied in enzymatic systems. Here, we reported DES-buffer co-solvent as a novel reaction medium for high efficient synthesis of cefaclor by penicilin acylase immobilized on magnetic nanocrystalline cellulose. Effect of DES composition, DES-buffer ratio, temperature, pH, substrate ratio and substrate concentration was systematically investigated. In co-solvent consisting of choline chloride (ChCl):glycol-buffer (7:3, v/v), conversion of 7-ACCA was 94%, synthesis to hydrolysis ratio was 1.8, and yield of cefaclor reached 91%, higher than that in aqueous buffer with optimized yield of 84%, showing the great potential of DES as organic solvent alternative. To the best of our knowledge, this is the first example of biosynthesis of cefaclor in the DES-buffer co-solvent.