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We prepared Mo and Cr co-loaded ZSM-5 (Mo/Cr/ZSM-5) by a sequential impregnation method and applied it to methane dehydroaromatization (MDA) reaction.

Sasaki K., Hernandez Gaitan J.A., Tokuda Y., et al. A nanosheet molding method to estimate the size of bilayers suspended in liquids. Journal of Materials Chemistry C 10, 15816 (2022); https://doi.org/10.1039/D2TC03765C., Various methods have been developed to determine the size of molecular bilayer structures dispersed in liquids. We focused on the nanosheet (NS) growth inside the bilayers in hyperswollen lamellar (HL) phases. Here, we propose the method to evaluate the size of bilayers in liquid by observing palladium NSs (PdNSs) growing rapidly in the bilayers of the HL phase. It uncovered that the width of PdNSs depends on methanol concentration, on which the stability of the HL phase also depends. Considering that the stability of the HL phase is positively correlated with the width of bilayers, we concluded that the observation of PdNSs probably corresponds to the indirect measurement of the width of bilayers. This method will also be applied to various other bilayers. Moreover, the PdNSs of a few nanometers in thickness and several hundred nanometers in width show higher catalytic activity for the reduction reaction of 4-nitrophenol to 4-aminophenol than the previously reported Pd catalysts without any supports.

Gold nanoparticles (AuNP) were prepared by a solution plasma process in the presence of H2O2, and they were dispersed in an aqueous solution without any stabilizer generally used. The dispersion stability of the AuNP in an aqueous solution was evaluated by capillary zone electrophoresis (CZE). An anionic broad peak was detected with the AuNP by CZE based on its wide variations in size and net charge. The broad peak also suggests that the AuNP were well dispersed in an aqueous solution. The dispersion stability of AuNP was evaluated from the viewpoints of long-term dispersion, salt concentration, and organic cosolvent. The anionic broad peak attributed to the dispersed AuNP was successfully detected for at least 55 weeks from the preparation with less shot signals of the aggregates. The AuNP was also well dispersed in aqueous NaCl solutions with its concentrations up to 30 mmol L−1, as well as with ethanol co-solvent up to 40 %(v/v). The AuNP prepared by the solution plasma process was proved to be highly stable in an aqueous solution.

Diamond-Like Carbon (DLC) is a promising engine material for reducing friction and wear on sliding parts. By contrast, MoDTC lubricant additives are known to promote the wear of a-C:H films. However, the mechanism that promotes wear and the formation of tribofilms on DLC parts when in contact with molybdenum-based lubricant additives has not been sufficiently studied. The purpose of this research is to determine the wear promotion mechanism and formation of tribofilm on DLC by lubricant additives by comparing friction and wear properties. We conducted friction and wear tests using a tribometer with DLC (ta-C, ta-C:H, a-C, and a-C:H) blocks, FC250 (cast iron) rings, and oils containing lubricant additives (MoDTC, MoDTP, and Mo without DTC ligand) by observing and analyzing the sliding surfaces of specimens. No wear was observed for any of the DLCs (ta-C, ta-C:H, a-C:H, and a-C) in combination with oils containing MoDTP or Mo without DTC ligands. Oil containing MoDTC revealed low frictional properties for all tested DLCs (ta-C, ta-C:H, a-C:H, and a-C), but arc-shaped wear occurred on a-C:H, which has low hardness and contains hydrogen only in combination with MoDTC-containing oil. In addition, MoO3 was most frequently detected on the worn surface of FC250 in combination with a-C:H and MoDTC-containing oil, whereas Mo carbide was seldom detected by XPS analysis of any worn surface or deposit. These results indicated that the constitution of the DLC and the hydrogen content are the main factors driving wear promotion by MoDTC, while MoO3 is the main factor promoting wear in a-C:H.

Koki Sasaki, Koji Miyake, Yoshiaki Uchida et al. Mechanochemical Synthesis of Dispersible Platinum Nanosheets for Enhanced Catalysis in a Microreactor. ACS Applied Nano Materials, 5 (4), 4998-5005, April 22, © 2022 American Chemical Society. https://doi.org/10.1021/acsanm.1c04583, Nanosheet fabrication usually requires some self-assembly process of the ingredients themselves or self-assembled templates to lead to the local anisotropy. Macroscopic forces and dynamics cannot usually generate the local anisotropy to synthesize nanosheets in a solution because the anisotropies of the macroscopic mechanical forces and dynamics are promptly relaxed in the molecular scale in a liquid phase. Here, we report the mechanochemical synthesis of dispersible platinum nanosheets (PtNSs) using a microreactor. This work is the first example of bottom-up nanosheet synthesis of a nonexfoliable compound in a microflow reactor. The nanosheets grow through the lateral fusion of nanoplatelets in the hydrophilic space of the stable hyperswollen lyotropic lamellar (HL) phase of a surfactant solution. The lateral fusion is accelerated as the flow rate increases because the area of the bilayer in the HL phase increases with shear stress. The mechanical energy to promote the growth of the PtNSs can also be extracted in different ways. Most simply, syringe pumps electrically generate it. We also illustrate mechanochemical synthesis using gravity, the most universal and eco-friendly energy source on the earth. It is also the first example of the fabrication of anisotropic nanoparticles using gravity. Larger PtNSs show higher catalytic activity for the reduction reaction from 4-nitrophenol to 4-aminophenol due to their dispersibility; surprisingly, the exponential increase of the fusion patterns of nanoplatelets dramatically reduces the agglomeration of PtNSs. These PtNSs perform better in catalysis and should be promising for hydrogen production, fuel cells, and sensors because of their large surface area and dispersibility. This method could open up a pathway to valuable nanosheets.

Zr-doped SAPO-34 has enhanced Lewis acidity, leading to high catalytic activity for LDPE cracking.

Mg and Zn co-doped mesoporous ZSM-5 was prepared via impregnation of Mg and a Zn ion exchange using a commercial ZSM-5, which achieved a high yield of BTX and the improvement of catalyst lifetime on EDA reaction.

The synthesis strategy of highly dispersed Co/N-doped porous carbon materials using anion exchange resin and ionic liquids.

Vapor consisting of DMF and HCl promotes crystallization of in situ glycine-modified UiO-66.

This study evaluates the effect of loading various mono and divalent metals in Beta zeolite on low-density polyethylene (LDPE) cracking. We revealed that Tl and Ba ions enhanced Lewis acidity, leading to higher catalytic activity on LDPE cracking.

This study is one of the few to develop a strategy that inhibits coke deposition by loading Cr on zeolite defects. We revealed that Cr6+ species, which interacted with hydroxyl groups in the zeolite framework inhibited coke deposition.

Alkanedithiols were used for the conjugation of gold nanoparticles (AuNP) prepared by a solution plasma process. Capillary zone electrophoresis was utilized for the monitoring of the conjugated AuNP. When 1,6-hexanedithiol (HDT) was used as a linker, a resolved peak from the AuNP was detected in the electropherogram; the resolved peak was attributed to the conjugated AuNP. The resolved peak was developed with increasing concentrations of HDT, while the peak of the AuNP decreased complementary. The resolved peak also tended to develop along with the standing time at least up to 7 weeks. The electrophoretic mobility of the conjugated AuNP was almost identical over the HDT concentrations examined, suggesting that the conjugation of the AuNP did not proceed further, such as aggregate/agglomerate formation. The conjugation monitoring was also examined with some dithiols and monothiols. Resolved peak of the conjugated AuNP was also detected with 1,2-ethanedithiol and 2-aminoethanethiol.

N-doped carbon materials have attracted considerable attention as highly functional materials because nitrogen doping distorts the carbon lattice, changes charge density, and introduces additional defects. Among various positions of N...

Photo-induced crawling motion of a crystal of 3,3'-dimethylazobenzene (DMAB) on gold surfaces having different surface properties and various patterns was studied. DMAB crystals crawl continuously when exposed to UV and visible lights simultaneously from different directions. On a gold surface functionalized by a thiol having a hydroxyl group at the terminal (16-hydroxy-1-hexadecanethiol (HOC16SH)), the crystals crawled with a relatively high velocity (ca. 4 μm min-1), and they changed the crystal shape while keeping a distinct crystal face. On a gold surface functionalized by a thiol having an alkyl chain terminal (1-hexadecanethiol (C16SH)), the crawling was observed with a slower velocity (ca. 1.5 μm min-1). However, the shape of the crystals became a droplet-like shape soon after the irradiation started, and the shape persisted during the motion. Light intensity dependence of the crawling velocity of the droplet-like crystal on this surface showed that UV light has stronger dependence for the motion than the visible light. On a substrate with a stripe pattern of alternating C16SH-modified gold and hexadecyltrimethylsilane (HDTMS)-modified glass, crystals crawled only on the surface of the C16SH-modified gold, which may be due to the wettability hysteresis at the surface. On a substrate with a stripe pattern of HOC16SH-modified gold and HDTMS-modified glass, crystals were attracted to the gold side. On a gold substrate with a periodic pattern of different height (ca. 50 nm) but having a uniform treatment with C16SH, crystals crawled up and down the steps without significant disturbance at the boundary of the step. Therefore, wettability of the surface has a greater impact on controlling the motion of the crystal than the surface structure. The present results not only unveil the crawling behavior on various surfaces but also offer a guide to controlling the motion toward applications for novel carriage vehicles to transport molecules/objects on a surface.

Electrochemical machining (ECM) is applied to a wide variety of metal processing. While ECM has many machining characteristics, bubbles and electrolytic product disturb current flow and decrease the machining efficiency. To apply ECM to micro-shape machining, it is important to clarify the mechanisms of transitional and microscopic ECM processes. In this report, variations in the growth and diffusion of electrolytic product at each ECM power and at each electrolyte temperature were measured by a microscopic optical system and fast camera. The growth and diffusion of electrolytic product were investigated based on the experimental results. The relationship between machining characteristics such as machining speed and surface roughness, and thickness of electrolytic product that varied as the growth and diffusion conditions changed were experimentally investigated.

Recently, NiSx based catalysts are promising electrocatalysts for Hydrogen Evolution Reaction (HER) via water electrolysis. In particular, the S/Ni ratio is crucial to improve catalytic activity of NiSx based catalysts. Herein, we synthesized NiSx based catalysts (Ni/S/C) with a tuned S/Ni molar ratio using Ni2+ ions exchange resin. We succeeded in synthesizing Ni/S/C with different S/Ni molar ratio in the range of 0.33–1.72 by changing Ni2+ ions exchange degree. The combination of NiSx and conductive carbon support contributes to high catalytic activity of Ni/S/C on HER. Additionally, Ni/S/C with the S/Ni molar ratio of 0.6 showed the highest onset potential; Ni3S2 is the most active catalyst for HER in NiSx species. Our synthesis method can easily tune the ratio of S/transition metal. This work provides a new direction for the catalyst design of transition metal sulfides and expands their utilization in sustainable catalytic reaction processes.

Sasaki Koki, Gaitan Jose A. Hernandez, Okue Tsuyoshi, et al. Amorphous Aluminosilicate Nanosheets as Universal Precursors for the Synthesis of Diverse Zeolite Nanosheets for Polymer‐Cracking Reactions. Angewandte Chemie 134, (2022); https://doi.org/10.1002/ange.202213773., Zeolites catalyze some reactions in their molecular-sized pores, but large molecules can react only on their external surface. Zeolite-nanosheets (NSs) have been developed as catalysts for large molecules. The previously reported methods to synthesize zeolite-NSs are specialized for each zeolite type. Here we propose a new method to synthesize various zeolite-NSs from the same amorphous aluminosilicate NSs (AAS-NSs) as a universal precursor. We successfully synthesized the unprecedented AAS-NSs in the hydrophilic space of the stable hyperswollen lyotropic lamellar (HL) phase. The four zeolite types could be obtained from the single-species AAS-NSs. These results imply that this method enables us to synthesize almost all types of zeolite-NSs. Moreover, the synthesized CHA-NSs have great potential for various applications because of their thickness and large external surface area.

The effects of nanomolding characteristics on an antireflective surface fabricated via injection molding were investigated. The optical property of a sub-wavelength structure (SWS) of our own making was also measured. The sizes of nanostructures fabricated on SWS molds were controlled by changing the average particle diameters used as mask and the time of reactive ion etching. The maximum filling ratio of the injected polymer was increased from 51.7% to 90.4% by changing the average particle diameters from 83.8 nm to 111.2 nm. In addition, the filled ratio of the injected polymer was increased from 51.7% to 73.7% under the same processing conditions. The results of the measurements of the optical property indicated that the reflectance of small-sized and large-sized SWSs fabricated with the same process condition was decreased at the wavelengths of 550 nm and 980 nm, respectively. The wavelength showed that the minimum reflectance was varied from the visible range to the near-infrared range by changing the size of the SWS under the same processing condition. This result led us to conclude that we can obtain antireflection surfaces for any wavelength by varying the size of the SWS under the same injection-molding condition.

Chabazite SSZ-13 has attracted wide attention due to its physiochemical properties and excellent potential as a catalyst for various application. In this study, pure phase SSZ-13 CHA zeolite with wide range of Si/Al ratio has been synthesized in a fluoride-free media by dry gel conversion method where the conversion of SSZ-13 from aluminosilicates precursor gel occurs under water vapor. The difference between products produced by conventional hydrothermal synthesis method and the new method has been investigated and characterized with XRD, SEM, XRF, and N2 adsorption. Pure SSZ-13 with wide range of Si/Al up to 182 was obtained by dry gel conversion method while pure SSZ-13 with higher Si/Al ratio than 20 with similar starting gel composition could not synthesized by hydrothermal synthesis method. Our work has demonstrated that dry gel conversion method was an effective method to synthesize pure SSZ-13 with a wide range of Si/Al ratio under fluoride media-free condition.

An efficient and simple methodology was proposed to synthesize CHA zeolite without the use of solvent and OSDA. The synthesis strategy is based on a mechanochemical-assisted interzeolite transformation using only Na-type FAU zeolite and KOH as starting materials, for ease of handling and large-scale production. The role of KOH on crystal transformation behaviors and adsorption characteristics of the obtained CHA zeolite were investigated. The important factor was the loading KOH into the cages of starting FAU zeolite with adjusted appropriate amount. In this method, vapor-solid interzeolite transformation occurs by local rearrangement of silicon and aluminum species without accompanying macroscopic dissolution of FAU zeolite, resulting in formation of CHA zeolite maintaining the Si/Al ratio of the starting FAU zeolite.