Liquid-phase Synthesis Research Articles

Size control of sulfide-based solid electrolyte particles through liquid-phase synthesis

All-solid-state lithium-ion batteries (ASS-LiB) have garnered attention as the next-generation secondary batteries owing to their high safety and energy densities. The ASS-LiBs are composed of inorganic solid electrolytes, instead of an organic liquid electrolyte. Therefore, interstitial voids deteriorate the battery capacity, which is a serious problem with ASS-LiBs. A straightforward solution to this problem is to fill the voids using smaller particles. However, the particle size control is yet to be established, and there are insufficient studies on particle size control. In this study, nano-sized solid electrolyte particles of Li3PS4 (LPS), which is a typical sulfide solid electrolyte, was synthesized using a liquid-phase shaking method. The nucleation rate of LPS was improved using the submicron-sized Li2S as raw material, which was prepared through wet milling and dissolution-precipitation processes. Consequently, the liquid-phase shaking method with fine Li2S powder was successfully used to synthesize the nano-sized LPS particles with high ionic conductivity.

A Gas-Phase Migration Strategy to Synthesize Atomically Dispersed Mn-N-C Catalysts for Zn-Air Batteries.

Mn and N codoped carbon materials are proposed as one of the most promising catalysts for the oxygen reduction reaction (ORR) but still confront a lot of challenges to replace Pt. Herein, a novel gas-phase migration strategy is developed for the scale synthesis of atomically dispersed Mn and N codoped carbon materials (g-SA-Mn) as highly effective ORR catalysts. Porous zeolitic imidazolate frameworks serve as the appropriate support for the trapping and anchoring of Mn-containing gaseous species and the synchronous high-temperature pyrolysis process results in the generation of atomically dispersed Mn-Nx active sites. Compared to the traditional liquid phase synthesis method, this unique strategy significantly increases the Mn loading and enables homogeneous dispersion of Mn atoms to promote the exposure of Mn-Nx active sites. The developed g-SA-Mn-900 catalyst exhibits excellent ORR performance in the alkaline media, including a high half-wave potential (0.90 V vs reversible hydrogen electrode), satisfactory durability, and good catalytic selectivity. In the practical application, the Zn-air battery assembled with g-SA-Mn-900 catalysts shows high power density and prominent durability during the discharge process, outperforming the commercial Pt/C benchmark. Such a gas-phase synthetic methodology offers an appealing and instructive guide for the logical synthesis of atomically dispersed catalysts.

Synthesis and Self-Assembly of a Novel Cyclic Hexapeptide and Octapeptide

In recent decades, cyclic peptides have attracted great attention due to their unique properties. In this paper, novel cyclic hexapeptide (6) and octapeptide (9) were designed and synthesized using liquid phase synthesis methodology. They were characterized by FT-IR, 1HNMR spectroscopy, LC-MS, scanning electron microscopy (SEM) and atomic-force microscopy (AFM). We have used these cyclic peptides as novel building blocks to generate porous materials by self-assembly.

Theoretical and Experimental Evaluation of the Reduction Potential of Straight-Chain Alcohols for the Designed Synthesis of Bimetallic Nanostructures.

Recently, the development of bimetallic nanoparticles with functional properties has been attempted extensively but with limited control over their morphological and structural properties. The reason was the inability to control the kinetics of the reduction reaction in most liquid-phase syntheses. However, the alcohol reduction technique has demonstrated the possibility of controlling the reduction reaction and facilitating the incorporation of other phenomena such as diffusion, etching, and galvanic replacement during nanostructure synthesis. In this study, the reduction potential of straight-chain alcohols has been investigated using molecular orbital calculations and experimentally verified by reducing transition metals. The alcohols with a longer chain exhibited higher reduction potential, and 1-octanol was found to be the strongest among alcohols considered. Furthermore, the experimental evaluation carried out via the synthesis of metallic Cu, Ni, and Co particles was consistent with the theoretical predictions. The reaction mechanism of metallic particle formation was also studied in detail in the Ni-1-octanol system, and the metal ions were confirmed to be reduced via the formation of nickel alkoxide. The results of this investigation were successfully implemented to synthesize Cu-Ni bimetallic nanostructures (core-shell, wire, and tube) via the incorporation of diffusion and etching besides the reduction reaction. These results suggest that the designed synthesis of a wide range of bimetallic nanostructures with more refined control has become possible.

Synthesis of CaCu3Ti4O12: How Heat Treatment Influences Morphology and Dielectric Properties

A ceramic powder, the precursor of CaCu3Ti4O12, was prepared by liquid-phase synthesis in acetic acid. The synthesized samples were calcined at 200, 400, 600, 800, and 1100°C and then characterized by a set of physicochemical methods. An increase in annealing temperature induced changes in the particle size distribution and quantitative porosity parameters of the powder. Analysis of the dielectric spectra of suspensions of synthesized materials allowed us to conclude that high-temperature annealing of the powder leads to a decrease in relaxation time.

Preparation of Li3PS4–Li3PO4 Solid Electrolytes by Liquid-Phase Shaking for All-Solid-State Batteries

A solid solution of a 100Li3PS4·xLi3PO4 solid electrolyte was easily prepared by liquid-phase synthesis. Instead of the conventional solid-state synthesis methods, ethyl propionate was used as the reaction medium. The initial stage of the reaction among Li2S, P2S5 and Li3PO4 was proved by ultraviolet-visible spectroscopy. The powder X-ray diffraction (XRD) results showed that the solid solution was formed up to x = 6. At x = 20, XRD peaks of Li3PO4 were detected in the prepared sample after heat treatment at 170 °C. However, the samples obtained at room temperature showed no evidence of Li3PO4 remaining for x = 20. Solid phosphorus-31 magic angle spinning nuclear magnetic resonance spectroscopy results proved the formation of a POS33− unit in the sample with x = 6. Improvements of ionic conductivity at room temperature and activation energy were obtained with the formation of the solid solution. The sample with x = 6 exhibited a better stability against Li metal than that with x = 0. The all-solid-state half-cell employing the sample with x = 6 at the positive electrode exhibited a better charge–discharge capacity than that employing the sample with x = 0.

Liquid-Phase Synthesis, Sintering, and Transport Properties of Nanoparticle-Based Boron-Rich Composites

Nanostructuring boron-rich materials should significantly impact their thermal and electrical transport properties. Nonetheless, nanostructured monoliths of such materials could not be achieved in the 10 nm range so far, because of the large temperatures required to synthesize and produce boron-rich compounds. Such a nanostructuration may have important consequences for achieving a trade-off between enhanced electrical and low thermal conductivity in boron-rich materials, which are among the few materials enabling thermoelectric power generation above 1000 K thanks to their thermal stability, high positive Seebeck coefficients, and low thermal conductivity. In this study, we use a one-pot synthesis in inorganic molten salts to yield a nanocomposite consisting of metallic HfB2 nanocrystals dispersed in an insulating amorphous boron-rich matrix with a controlled volume fraction of nanocrystals from 16 to 56 vol %. We show that this controlled liquid-phase synthesis can be coupled to spark plasma sintering for densification preserving the nanostructure. The relationships between the reagent ratio in the liquid-phase synthesis, sintering conditions, and transport properties of the densified nanocomposites are then highlighted. We then design materials exhibiting metallic electrical conductivity related to the HfB2 nanocrystals, together with enhanced thermal dissipation attributed to the nanostructured amorphous boron matrix. Combined with the versatility offered by in-solution routes toward boride-based nanocomposites, this work opens a new avenue for tuning transport properties in boron-rich nanomaterials.

Liquid Phase Peptide Synthesis via One-Pot Nanostar Sieving (PEPSTAR).

Herein, a one‐pot liquid phase peptide synthesis featuring iterative addition of amino acids to a “nanostar” support, with organic solvent nanofiltration (OSN) for isolation of the growing peptide after each synthesis cycle is reported. A cycle consists of coupling, Fmoc removal, then sieving out of the reaction by‐products via nanofiltration in a reactor‐separator, or synthesizer apparatus where no phase or material transfers are required between cycles. The three‐armed and monodisperse nanostar facilitates both efficient nanofiltration and real‐time reaction monitoring of each process cycle. This enabled the synthesis of peptides more efficiently while retaining the full benefits of liquid phase synthesis. PEPSTAR was validated initially with the synthesis of enkephalin‐like model penta‐ and decapeptides, then octreotate amide and finally octreotate. The crude purities compared favorably to vendor produced samples from solid phase synthesis.

Liquid Phase Peptide Synthesis via One‐Pot Nanostar Sieving (PEPSTAR)

AbstractHerein, a one‐pot liquid phase peptide synthesis featuring iterative addition of amino acids to a “nanostar” support, with organic solvent nanofiltration (OSN) for isolation of the growing peptide after each synthesis cycle is reported. A cycle consists of coupling, Fmoc removal, then sieving out of the reaction by‐products via nanofiltration in a reactor‐separator, or synthesizer apparatus where no phase or material transfers are required between cycles. The three‐armed and monodisperse nanostar facilitates both efficient nanofiltration and real‐time reaction monitoring of each process cycle. This enabled the synthesis of peptides more efficiently while retaining the full benefits of liquid phase synthesis. PEPSTAR was validated initially with the synthesis of enkephalin‐like model penta‐ and decapeptides, then octreotate amide and finally octreotate. The crude purities compared favorably to vendor produced samples from solid phase synthesis.

Studying the Effects of Temperature on the Nucleation and Growth of Nanoparticles by Liquid-Cell Transmission Electron Microscopy.

Temperature control is a recent development that provides an additional degree of freedom to study nanochemistry by liquid cell transmission electron microscopy. In this paper, we describe how to prepare an in situ heating experiment for studying the effect of temperature on the formation of gold nanoparticles driven by radiolysis in water. The protocol of the experiment is fairly simple involving a special liquid cell with uniform heating capabilities up to 100 °C, a liquid-cell TEM holder with flow capabilities and an integrated interface for controlling the temperature. We show that the nucleation and growth mechanisms of gold nanoparticles are drastically impacted by the temperature in liquid cell. Using STEM imaging and nanodiffraction, the evolution of the density, size, shape and atomic structure of the growing nanoparticles are revealed in real time. Automated image processing algorithms are exploited to extract useful quantitative data from video sequences, such as the nucleation and growth rates of nanoparticles. This approach provides new inputs for understanding the complex physico-chemical processes at play during the liquid-phase synthesis of nanomaterials.

High Ionic Conductivity of Liquid-Phase-Synthesized Li3PS4 Solid Electrolyte, Comparable to That Obtained via Ball Milling

Recently, several sulfide solid electrolytes have been synthesized by liquid-phase synthesis for the commercialization of all-solid-state batteries. Unfortunately, the ionic conductivity for most of these electrolytes is unsatisfactory compared to that of solid electrolytes synthesized by conventional ball milling. This problem is attributed to different mechanisms between the liquid phase and the solid phase in reaction and formation. However, to the best of our knowledge, the effect of the solvent on the ionic conductivity of solid electrolytes has not been extensively investigated, although the identification of these properties is a key point in understanding the liquid-phase synthesis. Herein, the correlation between ionic conductivity and crystallinity originating from the solvents used has been investigated. As a result, the ionic conductivity of the electrolyte was found to be strongly dependent on polarity (δP) with low crystallinity. The highest ionic conductivity (5.09 × 10–4 S cm–1 at 25 °C) was obtained using butyl acetate, which exhibited the lowest δP. Moreover, the highest ionic conductivity of Li3PS4 produced by liquid-phase synthesis using butyl acetate was very comparable to that obtained by ball milling (5.14 × 10–4 S cm–1).

Peg derivatives for the synthesis of water-soluble cyanine dye Cy5

An effective method for the preparation of water-soluble cyanine dye Cy5 using the soluble polymers supported liquid-phase organic synthesis (LPOS) was proposed. Poly (ethylene glycol) methyl ether with a molecular weight of 2000 was used as a polymer substrate, which allowed us to simplify the characterization of products at intermediate stages of synthesis by NMR spectroscopy. This approach makes it easy to obtain the necessary cyanine dyes, which are widely used as fluorescent labels and are popular modifying reagents in biochemistry and medicine.

The Effect of a Peptide Substrate Containing an Unnatural Branched Amino Acid on Chymotrypsin Activity

7-Amino-4-methylcoumarin (AMC) is a low molecular weight fluorescent probe that can be attached to a peptide to enable the detection of specific proteases, such as chymotrypsin, expressed in certain diseases. Because this detection depends on the specificity of the protease toward the peptidyl AMC, the development of specific substrates is required. To investigate the specificity of chymotrypsin, peptidyl AMC compounds incorporating four different amino acid residues were prepared by liquid-phase synthesis. Two unnatural amino acids, 2-amino-4-ethylhexanoic acid (AEH) and cyclohexylalanine (Cha), were used to investigate the substrate specificity as these amino acids have structures different from natural amino acids. AEH was synthesized using diethyl acetamidemalonate as a starting material. The substrate containing Cha had high hydrophobicity and showed a high reaction velocity with chymotrypsin. Although the AEH substrate with a branched side chain had high hydrophobicity, it showed a low reaction velocity. The substrate containing the aromatic amino acid phenylalanine was less hydrophobic than the Cha and AEH substrates, but chymotrypsin showed the highest specificity for this compound. These results demonstrated that the substrate specificity of chymotrypsin is not only affected by the hydrophobicity and aromaticity, but also by the structural expanse of amino acid residues in the substrate.

Improvement of lithium ionic conductivity of Li3PS4 through suppression of crystallization using low-boiling-point solvent in liquid-phase synthesis

Liquid-phase synthesis for solid electrolytes has received considerable attention owing to its shape control, with the potential to produce particles easily on a large scale, and its low cost and energy consumption. However, solid electrolytes prepared through liquid-phase synthesis have been shown to have lower ionic conductivity than solid electrolytes prepared through the mechanical milling method. Recently, following various efforts, our group found that the crystallinity and remaining intermediate are the reasons for the low ionic conductivity of these materials. By using tetrahydrofuran (THF), we successfully improved the ionic conductivity of Li3PS4 to 1.85 × 10−4 S cm−1 at 25 °C, higher than that afforded by ethyl propionate, which was reported to produce the highest ionic conductivity among the solvents used for liquid-phase synthesis. High-energy X-ray diffraction (XRD) measurements coupled with pair distribution function (PDF) analysis were employed to analyze the synthesized materials in order to determine why the ionic conductivity was higher than that of a sample prepared using ethyl propionate. The PDF analysis revealed that the crystallization of Li3PS4 can be suppressed using THF, which has a lower boiling point than ethyl propionate. Moreover, it was revealed that the solvent could not be removed completely when the material has an amorphous structure, and thus, the ionic conductivity was lower than that of a material prepared using the solid-phase synthesis method.

Electron Precise Sodium Carbaboride Nanocrystals from Molten Salts: Single Sources to Boron Carbides.

Boron-rich solids exhibit specific crystal structures and unique properties, which are only very scarcely addressed in nanoparticles. In this work, we address the original inorganic structural chemistry and reactivity of boron-rich nanoparticles, by reporting the first occurrence of sodium carbaboride nanocrystals based on the NaB5C crystal structure. To design these sub-10 nm nano-objects, we use liquid-phase synthesis in molten salts at 900 °C. By combining a set of characterization tools including powder X-ray powder diffraction, transmission electron microscopy, solid-state nuclear magnetic resonance coupled to DFT modeling, and X-ray photoelectron spectroscopy, we demonstrate that these nanocrystals deviate from the ideal stoichiometry reported for the bulk compound. We suggest that the carbon and sodium contents compensate each other to ensure that the octahedral cluster-based framework is stabilized by fulfilling an electron counting rule. These nanocrystals encompass substituted octahedral covalent structural building units not reported in the related bulk compound. They then shed new light on the ability of nanoparticles to host wide solid solution ranges in covalent solids and then to yield new solids. We finally show that these nanocrystals are efficient single sources of boron and carbon to form a nanostructured boron carbide, thus paving the way to new nanostructured materials.

Tag‐Assisted Liquid‐Phase Synthesis of Peptoids

Optimized reaction conditions for the tag-assisted liquid-phase synthesis of peptoids are reported. A peptoid heptamer was obtained in >90% crude purity at an elevated temperature and in chloroform. This liquid-phase peptoid synthesis can be an alternative method for preparing large quantities of peptoid oligomers.

Liquid-phase synthesis of highly oxophilic zerovalent niobium and tantalum nanoparticles

Zerovalent niobium, Nb(0), and tantalum, Ta(0), nanoparticles are prepared via a one-pot, liquid-phase synthesis. For this, NbCl5/TaCl5 are dissolved in pyridine and reduced by lithium pyridinyl. Deep black suspensions of very small, highly uniform nanoparticles are obtained with average diameters of 2.1 ± 0.4 nm (Nb(0)) and 1.9 ± 0.4 nm (Ta(0)). Whereas suspensions are chemically and colloidally stable, powder samples are very reactive. TEM/HRTEM, XRD, FT-IR, and XANES are used for characterization.

Composite Metal-Matrix Alloys Based on Ni-Al for Obtaining Wear-Resistant Coatings by Electric Spark Deposition

The paper presents the research results on produsing by the method of liquid-phase self-propagating high-temperature synthesis (SHS) the composite metal-matrix alloys intended for the obtaining of wear-resistant coatings by electric spark deposition (ESD). Oxides NiO, Cr2O3 and mineral concentrate ZrO2 were used as a melting charge. Alloys based on the Ni-Al system with aluminides of complex composition containing Cr and Zr were obtained by means of the alumothermic SHS reaction. Wear-resistant coatings were formed on steel 45 by the ESD method by means of the newly obtained alloys,. The maximum wear resistance of the coatings was obtained using the alloys containing Cr (wt% 18) and Zr (wt% 1.9).

Molecular level precision and high molecular weight peptide dendrimers for drug-specific delivery.

Peptide dendrimers have a broad application in biomedical science due to their biocompatibility, diversity, and multifunctionality, but the precision synthesis of high-molecule weight peptide dendrimers remains challenging. We here report the facile and liquid-phase synthesis of molecular level precision and amino-acid built-in polylysine (PLL) dendrimers with molecular weights as high as ∼60 kDa. Three types of polyhedral oligosilsesquioxane (POSS)-cored PLL dendrimers with phenylalanine, tyrosine, or histidine as building blocks were synthesized. The precise structures of the dendrimers were confirmed by MALDI-TOF MS, GPC, and 1H NMR spectroscopy. The interior functionalized peptide dendrimers improved the encapsulation capability of SN38 and sustained the release profiles. Enhanced molecular interactions between the peptide dendrimers and drugs were explored by both NMR experiments and computer simulations. The peptide dendrimer/SN38 formulations showed potent antitumor activity against multiple cancer cell lines. We believe that this strategy can be applied to the synthesis of tailor-made functional peptide dendrimers for drug-specific delivery and other diverse biomedical applications.

The Development of Ion-Conducting Hybrid Membranes Based on Cross-Linked Poly(vinyl alcohol) Using a Latin Square

Hybrid ion-conducting membranes (HIMs) are obtained by the liquid-phase synthesis method, and the degree of their swelling in water and ionic conductivity are studied. The design of a multifactorial experiment by the Latin square method makes it possible to select the optimum ratio of the functional components of the HIMs. It is found that the obtained hybrid membranes are anion-conducting.