Nonaqueous Synthesis Research Articles

Effects of cores types on non-solvent displacement nonaqueous precipitation synthesis of core-shell structured materials: A case study on effects of carbon sources on C@ZrSiO4 preparation

Effects of cores types on non-solvent displacement nonaqueous precipitation synthesis of core-shell structured materials were investigated via taking case study on effects of carbon sources on C@ZrSiO4 preparation. The influencing mechanism of carbon sources was investigated via XRD, FE-SEM, TEM and the CIELAB colorimeter. The results show that the optimized carbon source for non-solvent displacement nonaqueous precipitation synthesis of C@ZrSiO4 is amorphous and isolated spheroid-like carbon source. Neither layer-structured particle nor sheet-like particle can be effectively encapsulated through non-solvent displacement nonaqueous precipitation method. The shell layer is difficult to be effectively encapsulated on the edges of the around of corresponding particle. In comparison with the higher crystallinity core, the amorphous core is more favorable for encapsulation. The core materials selection principles discovered in this work are expected to be widely referred in the preparation of other core-shell structural materials.

Group Replacement-Rearrangement-Triggered Linear-Assembly Nonaqueous Precipitation Synthesis of Hydroxyapatite Fibers.

A novel method for hydroxyapatite fiber preparation with highly large-scale production prospects is of paramount importance but remains particularly difficult. Here, group replacement-rearrangement-triggered linear-assembly nonaqueous precipitation synthesis has been proposed for hydroxyapatite fibers under mild conditions. Pure hydroxyapatite fibers can be fabricated taking disodium hydrogen phosphate, calcium acetate, and glycerol as the phosphorus source, calcium source, and solvent, respectively. Single hexagonal crystal structures of hydroxyapatite fibers growing along the c-axis and preferential growth of the (002) crystal plane similar to the layered stacking structure of an adult bone have been confirmed by XRD refinement tests and calculation, TEM electron diffraction calibration, and FE-SEM. Highly active carbonate apatite is further demonstrated by EDS, FT-IR, Raman spectroscopy, and XPS. Unsaturated P-O and O-Ca bonds at both ends of the hexagonal-sheet assembly unit in a high-polarity nonaqueous glycerol environment without strongly coordinated OH- confirm the solution spontaneous linear assembly to form the single hydroxyapatite fibers.

Hierarchically open-capsule metal–organic frameworks via controlled etching for enzyme encapsulation

Nanocapsules with large accommodation interior space and exterior shell present a wide range of potential applications for storage, catalysis and drug delivery. However, conventional nanocapsules feature enclosed shells, which reduce the available surface areas for target molecule loading and pose mass transfer resistance. Here, we present a facile strategy for fabrication of hierarchically open-capsule metal–organic frameworks by utilizing a controlled self-etching process. Benefiting from the exposed surface of the openings on the wall and intrinsic stability of the MOFs, this open-capsule MOF (ocMOF) exhibits remarkably higher loading efficiency for lipase (3 times higher than unmodified MOFs). With commercialized lipase product Novozym 435 (N435) as bench mark, the obtained CALB@ocMOF showed 11.3-fold higher catalytic efficiency, with kcat/Km of 186 mM−1·s−1 and comparable stability under hostile conditions. As a proof-of-concept, the prepared CALB@ocMOF was used for non-aqueous enzymatic synthesis of retinyl palmitate, bioavailable substances beneficial for human health, with 3.2-times higher catalytic activity than N435. This study would afford prospects for developing MOFs capsule for biotechnology application.

Elucidating the role of seed structure in the heterometallic seeded growth of copper-based nanocrystals

Seed-mediated synthesis is a versatile method to prepare multimetallic nanocrystals for diverse applications. However, many fundamental questions remain on how the structural and chemical properties of nanocrystal seeds control the reaction pathways, especially for nonaqueous synthesis at elevated temperatures. Herein, we elucidate the role of surface ligands and crystallinity of Au nanocrystal seeds on the heterometallic seeded growth of Cu-based nanocrystals. We found that weakly coordinating ligands are critical to facilitate the diffusion between Au and Cu, which enables subsequent one-dimensional growth of Cu. Replacing multiple-twinned Au seeds with single-crystalline ones switched the growth pathway to produce heterostructured nanocrystals. Our work illustrates the importance of precise control of seed characteristics for the predictive synthesis of structurally complex multimetallic nanocrystals.

Oxygen-deficient low band gap black zirconia nanoparticle synthesis and tailoring its band gap/photoluminescence via silver doping

This study focuses on the non-aqueous sol-gel synthesis of zirconia nanopowder and explores the tunability of its band gap, absorption, and photoluminescence. Multiple characterization techniques were used to examine the impact of oxygen vacancies (color centers) and silver doping on changes in the structural and optical properties of zirconia. XRD results confirmed the rare black-colored pure tetragonal zirconia and monoclinic-tetragonal mixed zirconia products. The UV–Vis analysis provided insights about the absorbance and confirmed the extraordinarily high absorbance over the entire visible spectrum of electromagnetic radiation and also ascertained the defect level that governed the low band gap of the synthesized black zirconia powders. With increasing the doping concentration, the photoluminescence emission spectroscopy stimulated at an excitation wavelength of 250 nm revealed a rising luminescence peak at 422 nm (2.94eV). The distinctive stretching modes of zirconia powder samples were validated by FTIR investigations. The FESEM was used to study the microstructure's morphology, and the EDX spectrum was used to analyze the samples' elemental composition. The high-bandgap white samples with strong PL emission (blue) can be used to create high-quality wLEDs, whereas the low-bandgap black zirconia may prove to be an outstanding solar light absorption material.

Enhanced adsorption of methylene blue by mixed-phase bismuth ferrite prepared by non-aqueous sol-gel route

We report here a non-aqueous sol-gel synthesis of bismuth ferrite (BFO) particles in THF, DMF, and DMSO solvents, their subsequent utilization in adsorption of methylene blue, and a comparison of their adsorption efficiencies. BFO is attractive for adsorption because of its excellent dispersion in water. XRD data shows that all the solvents yield a mixture of a primary rhombohedral and a secondary orthorhombic phases with varying fractions. The DMSO yields the most impure samples having the highest fraction of secondary phase. However, the adsorption efficiencies of the samples order as DMF < THF < DMSO, with DMF showing 26.28 %, THF 51.63 %, and DMSO 96.54 %. A higher refractive index and donicity of DMSO leads to better solvation of the sol and incorporation of sulfur in the metal-oxide network during the sol-gel reaction. DMSO aids in columnar growth of orthorhombic phase, which, due to sulfur incorporation, forms a more open and less crystalline phase, which are the factors responsible for DMSO samples showing enhanced adsorption. Analysis of adsorption kinetics and isotherm on the DMSO samples confirms diffusive regimes pertaining to film-diffusion and intra-particle diffusion with the diffusive kinetics becoming faster at higher dye concentration. Fitting to Langmuir isotherm yields maximum monolayer coverage of 7.14 mg of dye per g of the adsorbent. The DMSO samples also show excellent adsorption at high pH conditions.

Fast and High‐Yield Anhydrous Synthesis of Ti3C2Tx MXene with High Electrical Conductivity and Exceptional Mechanical Strength (Small 46/2022)

MXene Synthesis In article number 2203767, Chong-Min Koo and co-workers show that a high temperature non-aqueous synthesis of Ti3C2Tx can significantly enhance the reaction rate and yield of delaminated MXene flakes with high quality. Additionally, Ti3C2Tx prepared by this method is covered with more F-terminations and exhibits high tensile strength. These findings offer new opportunities towards diversifying synthetic pathways and synthesizing novel MXene structures.

Incorporating Copper to Biodegradable Magnesium Alloy Vascular Stents via a Cu(II)‐Eluting Coating for Synergistic Enhancement in Prolonged Durability and Rapid Re‐Endothelialization

AbstractBiodegradable magnesium‐based scaffolds present outstanding potential to revolutionize the treatment of coronary artery diseases, in which full recovery of arteries without long‐term irritation of implants is anticipated for averting adverse events associated with the permanent stents. However, overfast degradation of magnesium (Mg) alloys obstructs their extensive applications in terms of early structural failure and impaired biocompatibility. Herein, a facile copper‐incorporated coating system through nonaqueous phase synthesis of polydopamine is developed to facilitate Cu(II) capture along with robust film deposited on easily corrodible Mg, which subsequently enables sustained Cu(II) elution. It remarkably enhances corrosion resistance and impedes Mg degradation, which also contributes to improved, superior cytocompatibility, and abolished hemolysis. Moreover, through simultaneous control of Cu(II) and Mg(II) release to modulate the local microenvironment, a synergistic biochemical effect on desirable vascular cell selectivity is triggered for boosted endothelial cell viability and suppressed smooth muscle cell. Stent implantation into rabbit abdominal aorta thus exhibits accelerated re‐endothelialization completed in a week, and enhanced biological outcomes, alleviated complications and prolonged structural durability in 3‐month follow‐up. Collectively, this study opens up an alternative route of deploying a multifunctional surface modification strategy tailoring active interplay with the Mg matrix for better outcomes of next‐generation bioresorbable vascular stents.

Oxygen-Enhanced Chemical Stability of Lithium-Mediated Electrochemical Ammonia Synthesis.

Although oxygen added to nonaqueous lithium-mediated electrochemical ammonia synthesis (LiMEAS) enhances Faradaic efficiency, its effect on chemical stability and byproducts requires understanding. Therefore, standardized high-resolution gas chromatography–mass spectrometry and nuclear magnetic resonance were employed. Different volatile degradation products have been qualitatively analyzed and quantified in tetrahydrofuran electrolyte by adding some oxygen to LiMEAS. Electrodeposited lithium and reduction/oxidation of the solvent on the electrodes produced organic byproducts to different extents, depending on the oxygen concentration, and resulted in less decomposition products after LiMEAS with oxygen. The main organic component in solid-electrolyte interphase was polytetrahydrofuran, which disappeared by adding an excess of oxygen (3 mol %) to LiMEAS. The total number of byproducts detected was 14, 9, and 8 with oxygen concentrations of 0, 0.8, and 3 mol %, respectively. The Faradaic efficiency and chemical stability of the LiMEAS have been greatly improved with addition of optimal 0.8 mol % oxygen at 20 bar total pressure.

Nonaqueous Chemistry of Group 4 Oxo Clusters and Colloidal Metal Oxide Nanocrystals.

We review the nonaqueous precursor chemistry of the group 4 metals to gain insight into the formation of their oxo clusters and colloidal oxide nanocrystals. We first describe the properties and structures of titanium, zirconium, and hafnium oxides. Second, we introduce the different precursors that are used in the synthesis of oxo clusters and oxide nanocrystals. We review the structures of group 4 metal halides and alkoxides and their reactivity toward alcohols, carboxylic acids, etc. Third, we discuss fully condensed and atomically precise metal oxo clusters that could serve as nanocrystal models. By comparing the reaction conditions and reagents, we provide insight into the relationship between the cluster structure and the nature of the carboxylate capping ligands. We also briefly discuss the use of oxo clusters. Finally, we review the nonaqueous synthesis of group 4 oxide nanocrystals, including both surfactant-free and surfactant-assisted syntheses. We focus on their precursor chemistry and surface chemistry. By putting these results together, we connect the dots and obtain more insight into the fascinating chemistry of the group 4 metals. At the same time, we also identify gaps in our knowledge and thus areas for future research.

Research trends in the development of anodes for electrochemical oxidation of wastewater

Abstract The review focuses on the recent development in anode materials and their synthesis approach, focusing on their compatibility for treating actual industrial wastewater, improving selectivity, electrocatalytic activity, stability at higher concentration, and thereby reducing the mineralization cost for organic pollutant degradation. The advancement in sol–gel technique, including the Pechini method, is discussed in the first section. A separate discussion related to the selection of the electrodeposition method and its deciding parameters is also included. Furthermore, the effect of using advanced heating approaches, including microwave and laser deposition synthesis, is also discussed. Next, a separate discussion is provided on using different types of anode materials and their effect on active •OH radical generation, activity, and electrode stability in direct and indirect oxidation and future aspects. The effect of using different synthesis approaches, additives, and doping is discussed separately for each anode. Graphene, carbon nanotubes (CNTs), and metal doping enhance the number of active sites, electrochemical activity, and mineralization current efficiency (MCE) of the anode. While, microwave or laser heating approaches were proved to be an effective, cheaper, and fast alternative to conventional heating. The electrodeposition and nonaqueous solvent synthesis were convenient and environment-friendly techniques for conductive metallic and polymeric film deposition.

Microwave-Assisted Non-aqueous and Low-Temperature Synthesis of Titania and Niobium-Doped Titania Nanocrystals and Their Application in Halide Perovskite Solar Cells as Electron Transport Layers.

Undoped and Nb-doped TiO2 nanocrystals are prepared by a microwave-assisted non-aqueous sol–gel method based on a slow alkyl chloride elimination reaction between metal chlorides and benzyl alcohol. Sub-4 nm nanoparticles are grown under microwave irradiation at 80 °C in only 3 h with precise control of growth parameters and yield. The obtained nanocrystals could be conveniently used to cast compact TiO2 or Nb-doped TiO2 electron transport layers for application in formamidinium lead iodide-based photovoltaic devices. Niobium doping is found to improve the cell performance by increasing the conductivity and mobility of the electron transport layer. At the same time, a measurable decrease in parasitic light absorption in the low wavelength portion of the spectrum was observed.

Non-Aqueous Liquid Phase Synthesis of Acetic Acid via Ionic Liquid Promoted Homogeneous Carbonylation of Methanol over Ir(III) Catalysts

Abstract Carbonylation of methanol to acetic acid is an aqueous homogeneous catalytic process widely used in industry. In the existing methanol carbonylation industry, a large amount of water (14–15 wt.%) is required in the Monsanto process to inhibit catalyst deactivation, which also consumes a lot of energy to separate the water from the acetic acid product. Here, non-aqueous liquid phase synthesis of acetic acid was carried out by ionic liquid promoted homogeneous carbonylation of methanol over Ir(III) catalysts. It was found that 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([Bmim]Tf2N) and N-butyl pyridinium bis(trifluoromethanesulfonyl)imide ([BPy]Tf2N) could promote the acetic acid selectivity (&amp;gt;98%) and methanol conversion (&amp;gt;99%) under a relatively mild reaction condition of 160 °C and 3.0 MPa. In the reaction, Tf2N− formed an Ir*[Tf2N] complex with Ir to promote the stability of Ir and enhance the activation of CO. From DFT calculation results, the CO insertion was a rate controlling step on the Ir-base catalyst in the reaction cycle, determining the conversion and selectivity of the reaction. The oxygen and nitrogen groups from Tf2N− interacted with Ir to form an Ir*[Tf2N] complex, which could effectively reduce the energy barrier of the CO insertion step, enhancing the selectivity of HAc. Moreover, the catalyst system could be easily recycled and reused with the methanol conversion of 89.66% after five cycles. The methanol carbonylation based on the ionic liquid promoted catalyst is a promising non-aqueous liquid-phase sustainable process.

Photoluminescence of zinc sulfide doped with Mn-=SUP=-2+-=/SUP=- and Eu-=SUP=-3+-=/SUP=- ions in dodecane medium

Photoluminescence (PL) of zinc sulfide powder synthesized and doped with Mn2+ and Eu3+ ions by the method of emerging reagents in a dodecane medium was investigated. In the absorption and excitation spectra of the PL samples ZnS and ZnS : Mn2+(Eu3+), bands corresponding to the transitions of electrons from the valence band to the conduction band and to the levels of structural defects of ZnS, as well as bands of transition of 4f-electrons of Eu3+ ions from the ground 7F0 to excited electronic states were recorded. A wide band associated with recombination processes at the energy levels of defects on the surface of ZnS particles is observed in the PL spectra. Narrow bands of PL are attributed to 5D0-&amp;gt;7Fj and 4T1-&amp;gt;6A1 electronic transitions in Eu3+ and Mn2+ ions. They are associated with the intra-zone glow centers formed by these ions in the ZnS structure. Energy transfer from ZnS defect levels to excited energy levels of Eu3+ ions was registered. Assumptions are made about the mutual influence of ZnS and alloying ions, as well as about the influence of synthesis conditions on the spectral properties of substances. Keywords: non-aqueous synthesis, dodecane, zinc sulfide, alloying, manganese (II) ions, europium (III) ions, photoluminescence.

Copper substituted methyl ammonium lead bromide grown using Non-Aqueous emulsion based synthesis technique

Hybrid organic–inorganic lead halide perovskites have become a promising material in the field of optoelectronics because of their prospects in the opto-electronics industry. However, the presence of the element “Lead” makes them legislatively untouchable for large scale production and human use. Herein, we report a non-aqueous emulsion-based synthesis and characterization of Copper (Cu)-substituted methyl ammonium lead Bromide (CH3NH3Pb1-xCuxBr3) perovskite nanoparticles which has not been reported previously. This technique enables the synthesis of quantum confined nanostructures by precipitation from the colloidal mixture. The structural characterization of all the samples showed that the crystallization occurs in the orthorhombic phase for the pristine and copper substituted methyl ammonium lead bromide nanostructure. The samples prepared with the precursor stoichiometry of CH3NH3Pb0.6Cu0.4Br3 and CH3NH3Pb0.5Cu0.5Br3 exhibited improved crystallinity relative to the un-substituted perovskite material. We report that as Cu content increases the average crystalline size increases which leads to decrease in optical band gap. The change in Cu content did not alter the excitonic absorption indicating that the quality of the material was not compromised as a result of the Cu substitution.

Non-aqueous synthesis of high-quality Prussian blue analogues for Na-ion batteries.

A microwave-assisted solvothermal (MW-ST) method was developed to synthesize high-quality Prussian blue analogues. The tuned NaFeHCF exhibits low water content as well as good thermal stability. It delivers a high initial discharge capacity of 150 mA h g-1, good rate capability and cycling life over 500 cycles.

Non-aqueous synthesis of homogeneous molybdenum silicate microspheres and their application as heterogeneous catalysts in olefin epoxidation and selective aniline oxidation

In this work, a novel synthesis of homogeneous molybdenum silicate spheres under non-aqueous conditions is presented. A preparation method is based on the condensation of molybdenum metal–organic framework-based precursor solution prepared via a microwave-assisted approach from bis(acetylacetonato)dioxomolybdenum and biphenyl-4,4′-dicarboxylic acid with 3-aminopropyltriethoxysilane under non-aqueous conditions. The as-prepared product was calcined at 500 °C to obtain amorphous and porous molybdenum silicate microspheres with homogeneously distributed molybdenum species within silicate matrix. The microspheres exhibit an average size of about 480 nm. This material was further studied as a heterogeneous catalyst for the epoxidation of olefins via the model catalytic epoxidation of cyclohexene with cumylhydroperoxide. High catalytic activity at the moderate temperature (65 °C) with the conversion of 86% after 2 h and the high selectivity to cyclohexene oxide has been achieved. In addition, molybdenum silicate microspheres exhibit catalytic activity and high selectivity in the oxidation of aniline to nitrosobenzene.

Role of Fe (x = 0–0.15) Substitution on Structural, Magnetic, and Transport Properties of the La0.7Sr0.3FexMn1−xO3 System

This paper investigates the effect of Fe substitution on the structural, magnetic and transport properties of the La0.7Sr0.3MnxFe1−xO3 (LSMO) system where x ranged between 0 and 0.15. Samples were prepared using a non-aqueous sol-gel synthesis method. Structural and chemical analysis confirmed the Fe3+ substitution at Mn3+ sites without any impurity phase resulted in a small change in structural parameters of the LSMO. The change in magnetic behavior and Curie temperature of the Fe-doped LSMO is explained through competitive exchange interactions developed in the system. The temperature-dependent resistivity demonstrated that the resistivity of the samples increased with Fe concentration due to different conduction mechanisms related to the ferromagnetic-metallic and paramagnetic-insulating regions. The magneto-transport measurement showed significant improvement in the magnetoresistance due to Fe doping at Mn site, which was attributed to enhancement of the spin-glass phase in Fe doped LSMO system. The reduction in magnetoresistance for higher Fe concentration is explained with the help of percolation threshold mechanism.

Non-hydrolytic sol–gel route to a family of hybrid mesoporous aluminosilicate ethanol dehydration catalysts

Hybrid materials are intensely studied for potential applications in heterogeneous catalysis. Organic groups at the catalyst surface can modify not only its hydrophilicity, but also acidity, hydrothermal stability, porosity, etc. In some cases, tuning such properties leads to improved catalytic performance. Often, however, the organic moieties are limited to methyl groups introduced via post-grafting. Here, a series of mesoporous hybrid aluminosilicate materials was prepared in one pot by non-hydrolytic sol–gel (NHSG). Aromatic, aliphatic, pendant, and bridging organic groups were incorporated. The presence of the organic groups in the bulk and at the outermost surface of the materials was verified by solid-state NMR, IR, ToF–SIMS, and XPS. The hybrid aluminosilicates were tested as catalysts in the gas phase ethanol dehydration to ethylene, and most of them outperformed the inorganic catalyst benchmark. While a direct influence of surface hydrophobicity (as probed by water sorption and water contact angle measurements) appeared unlikely, characterization of acidity (IR-pyridine) revealed that the improved performance for hybrid catalysts could be correlated with a modification of the acidic properties. The latter are determined by the quality of the dispersion of Al centers in the form of isolated sites in the hybrid silica matrix, which itself appears to be influenced by the presence of organic groups in the non-aqueous synthesis. All in all, this study establishes a "ranking" for a variety of organic groups in terms of their influence on the catalyst activity.

N-Doped Carbon Dots Synthesized from Ethylene Glycol and β-Alanine for Detection of Cr(VI) and 4-Nitrophenol via Photoluminescence Quenching

We present here a facile method for nonaqueous synthesis of highly crystalline nitrogen-doped carbon dots (N-CDs) via oligomerization of ethylene glycol while heating with β-alanine at 170 °C for 3...