Facile Synthesis of N-Doped Metal-Free Catalysts for Oxygen Reduction Reaction via a Self-Sacrificed Template Method Using Zinc Amino-Acid Complex.

Precisely controlled heteroatom-doped metal-free carbon catalysts are highly desirable for use in various renewable energy conversion and storage devices. Herein, we report a nitrogen-doped metal-free carbon catalyst for the oxygen reduction reaction (ORR) using a facile and cost-effective synthetic method. The obtained catalysts (NC-1100) were synthesized in two steps via an amino-acid complex coating and high-temperature carbonization. The various physical characteristics revealed that NC-1100 has a unique morphology, a controlled nitrogen bonding configuration, and a uniform pore distribution. The resulting catalyst shows excellent catalytic performance toward direct 4-electron oxygen reduction reaction (ORR) in an alkaline electrolyte, with a high onset potential of 0.95 V versus RHE and limiting current density (4.5 mA cm-2). Furthermore, the developed catalysts showed superior long-term operating stability and methanol durability compared to those of commercial Pt/C. This study provides a promising guideline for the development of next-generation electrocatalysts for fuel cells and wider applications.

Facile and Cost-effective Synthesis of CoP@N-doped Carbon with High Catalytic Performance for Electrochemical Hydrogen Evolution Reaction.

The manufacture of efficient and low-cost hydrogen evolution reaction (HER) catalysts is regarded as a critical solution to achieve carbon neutrality. Herein, we developed an economical method to synthesize a CoP-anchored N-doped carbon catalyst via one-step pyrolysis using inexpensive starting materials (cobalt ion salt, phytic acid, and glycine). The size of the CoP nanoparticles was controlled by adjusting the Co/P ratio of the catalysts. Nanoscale CoP particles with adequate exposure to active sites were uniformly anchored on the surface of the conductive nitrogen-doped carbon substrate, ensuring the rapid transfer of electrons and species. When Co/P=0.89, the as-made catalyst exhibited outstanding HER activity, with an extraordinarily low overpotential of 202 mV at 10 mA cm-2 and long-term stability.

A zeolite templating method for fabricating edge site-enriched N-doped carbon materials.

N-doped carbon materials have attracted considerable attention as highly functional materials because nitrogen doping distorts the carbon lattice, changes the charge density, and introduces additional defects. Among various positions of N atoms in N-doped carbon compounds, pyridinic-N, pyrrolic-N, and valley-N, which are doped at edge sites, exhibit specific electrocatalytic activities during the oxygen reduction reaction (ORR). However, it is difficult to selectively introduce these N atoms into a carbon matrix because the synthesis procedure typically includes high-temperature heat treatment. In this study, we applied a zeolite templating method to synthesize edge site-rich N-doped carbon materials. The sample fabricated using a zeolite template possessed high concentrations of pyridinic-N and valley-N atoms, demonstrating a significantly higher ORR catalytic activity than the sample synthesized without a zeolite template. Additional experiments conducted using various zeolites confirmed the positive effect of N-doped carbons on the ORR catalytic performance. This work demonstrated that the zeolite templating method not only increased the specific surface area and the number of active sites but also selectively created edge sites and improved the quality of the active sites.

Effect of Ga substitution with Al in ZSM-5 zeolite in methanethiol-to-hydrocarbon conversion.

The catalytic properties of conventional H-[Al]-ZSM-5 and gallium-substituted H-[Ga]-ZSM-5 were evaluated in the conversion of methanethiol to ethylene (CH3SH → 1/2C2H4 + H2S). Dimethyl sulfide (DMS), aromatics, and CH4 were formed as byproducts on the H-[Al]-ZSM-5 catalyst. The introduction of Ga into the ZSM-5 structure provided a high ethylene yield with relatively high selectivity for olefins. Based on the temperature-programmed desorption of NH3 and pyridine adsorption on zeolites, the strength of acid sites was decreased by introducing Ga into the ZSM-5 structure. Undesirable reactions seemed less likely to occur at weakly acidic sites. The suppression of the formation of dimethyl sulfide (CH3SH → 1/2C2H6S + 1/2H2S) and the sequential reaction of ethylene to produce aromatics provided a high yield of ethylene over H-[Ga]-ZSM-5.

Conjugation monitoring of gold nanoparticles with alkanedithiols by capillary zone electrophoresis.

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.

Solvent-Free Soft-Template Synthesis of Highly Ordered Mesoporous Carbons via Self-Assembly Promoted by Mg(NO3)2.

To improve the pore uniformity and volume of ordered mesoporous carbons produced by soft templating under solvent-free conditions, magnesium nitrate inorganic salt was incorporated into the precursors during the synthesis. The addition of magnesium nitrate in this procedure lowered the melting point of resorcinol, increased the diffusivity of the resorcinol-Pluronic F127 complex, and promoted self-assembly. The entry of Mg species into the core of the micelle of Pluronic F127 resulted in a modification of the pore structure resembling a channel-like hexagonal structure. In addition, the MgO in the pores effectively prevented the shrinkage of the mesopores under high-temperature conditions. Correspondingly, the uniformity and the mesopore volume of the mesoporous carbon obtained were also enhanced. Moreover, when used as electrodes, this ordered mesoporous carbon was able to significantly increase the capacity of electric double-layer capacitors. Thus, the current study proposes a novel method for regulating the structure and distribution of ordered mesoporous carbons.

Amorphous Aluminosilicate Nanosheets as Universal Precursors for the Synthesis of Diverse Zeolite Nanosheets for Polymer-Cracking Reactions.

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.

Highly stable gold nanoparticles in an aqueous solution without any stabilizer prepared by a solution plasma process evaluated through capillary zone electrophoresis.

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 co-solvent. 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.

Design of Zr- and Al-Doped *BEA-Type Zeolite to Boost LDPE Cracking.

Nowadays, the increase in plastic waste is causing serious environmental problems. Catalytic cracking has been considered a promising candidate to solve these problems. Catalytic cracking has emerged as an attractive process that can produce valuable products from plastic wastes. Solid acid catalysts such as zeolites decompose the plastic waste at a lower temperature. The lower decomposition temperature may be desirable for practical use. Herein, we synthesized both Zr- and Al-incorporated Beta zeolite using amorphous ZrO2-SiO2. The optimized Zr content in the dry gel allowed the enhancement of Lewis acidity without a significant loss of Brønsted acidity. The enhancement of Lewis acidity was mainly due to Zr species incorporated into the zeolite framework. Thanks to the enhanced Lewis acidity without any significant loss of Brønsted acidity, higher polymer decomposition efficiency was achieved than a conventional Beta zeolite.

Processes of molecular adsorption and ordering enhanced by mechanical stimuli under high contact pressure.

Adsorbed molecular films, referred to as boundary films in tribology, are widely used in various industrial products as a keyway for surface functionalisation, such as lubricity, wettability, and adhesion. Because boundary films are thin nanometre-scale molecular layers and can easily be removed, their formation process cannot be elucidated in detail. In this study, to analyse the growth dynamics of boundary films, the film thickness and molecular orientation of the boundary film of a fatty acid used as an additive in rolling contact as mechanical stimuli were measured in situ. The measurements were performed on simple test lubricants, which were composed of n-hexadecane and stearic acid, at rolling tribological condition between steel and glass (or sapphire) surfaces by ultrathin film interferometry combined with sum-frequency generation spectroscopy according to a unique protocol. The results quantitatively demonstrate shear-induced boundary film formation. The insight gained from these results is anticipated to enable the formulation of high-performance lubricant additives to further reduce friction loss and high-performance glues that can be freely designed for removability.

Photo-Induced Crawling Motion of Azobenzene Crystals on Modified Gold Surfaces.

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.

Effect of Surface Properties on the Photo-Induced Crawling Motion of Azobenzene Crystals on Glass Surfaces.

Photo-induced crawling motion of a crystal of 3,3'-dimethylazobenzene (DMAB) on a glass substrate having different surface properties was studied. When exposed to UV and visible lights simultaneously from different directions, crystals crawl continuously on a glass surface. On a hydrophilic surface, the crystals crawled faster than those on other surfaces but crystals showed spreading while they moved. On hydrophobic surfaces, on the other hand, the crystals showed little shape change and slower crawling motion. The contact angles of the liquid phase of DMAB on surface-modified glass substrates showed positive correlation with the water contact angles. The interaction of melted azobenzene with glass surfaces plays an important role for the crawling motion. We proposed models to explain the asymmetric condition that leads to the directional motion. Specifically by considering the penetration length of UV and visible light sources, it was successfully shown that the depth of light penetration is different at the position of a crystal. This creates a nonequilibrium condition where melting and crystallization are predominant in the same crystal.

Thin ZIF-8 nanosheets synthesized in hydrophilic TRAPs.

The preparation method of nanosheets using hyperswollen lyotropic lamellar phases, the 'two-dimensional reactor in amphiphilic phases (TRAP) method', has successfully provided nanosheets of various non-layered materials. Previously reported examples started from a single hydrophobic or hydrophilic precursor and multiple hydrophobic precursors. Here, we propose a synthesis method of nanosheets of ZIF-8, zinc 2-methylimidazolate, with a sodalite-like framework. They grow up to a few nanometers of thickness and several hundred nanometers of width with neither aggregation nor impurities from multiple hydrophilic precursors in the stoichiometric ratio inside the hydrophilic TRAPs consisting of the amphiphile Brij L4. The thin nanosheets of ZIF-8 doped with Co2+ (Co-ZIF-8) synthesized by the same method maintained a high specific surface area after calcination. Therefore, the oxygen reduction reaction (ORR) activity of the calcined Co-ZIF-8 NSs for fuel cells becomes higher than that of the calcined conventional Co-ZIF-8 crystals.

In Situ Observation of Desorption and Direct Electron Transfer Reaction of Cytochrome c on Bare ITO Electrode with Electrochemical Slab Optical Waveguide Spectroscopy.

Cyclic voltammograms (CVs) of cytochrome c (cytc) on the bare ITO were measured with every 10 times of the continuous the solution exchange (SE) processes at the same time of slab optical waveguide (SOWG) spectral observation, and it was proved that direct electron transfer (DET) reaction functionality of cytc adsorbed on the bare ITO electrode was kept after 100 times SE processes. The existence of three kinds of cytc molecules which were weakly adsorbed, strongly adsorbed and immobilized on the bare ITO electrode below a monolayer coverage was indicated from the change in the Soret band absorbance at 408 nm due to the desorption reaction of cytc with In Situ observation by electrochemically controlled SOWG spectroscopy. As the actual procedure, 100 times of the SE process in the SOWG cell by hands induced the gradual decrease of the absorbance due to cytc desorption, and with every 10 times of the SE process SOWG absorption spectra were obtained. The SOWG absorbance decay curve was well fitted with two components exponential equation depending on the SE process numbers showing that around 31.6% of the cytc molecules adsorbed on bare ITO electrode were finally immobilized.

In situ Observation of Direct Electron Transfer Reaction of Cytochrome c Immobilized on ITO Electrode Modified with 11-{2-[2-(2-Methoxyethoxy)ethoxy]ethoxy}undecylphosphonic Acid Self-assembled Monolayer Film by Electrochemical Slab Optical Waveguide Spectroscopy.

To immobilize cytochrome c (cyt.c) on an ITO electrode while keeping its direct electron transfer (DET) functionality, the ITO electrode surface was modified with 11-{2-[2-(2-methoxyethoxy)ethoxy]ethoxy}undecylphosphonic acid (CH3O (CH2CH2O)3C11H22PO(OH)2, M-EG3-UPA) self-assembled monolayer (SAM) film. After a 100-times washing process to exchange a phosphate buffer saline solution surrounding cyt.c and ITO electrode to a fresh one, an in situ observation of visible absorption spectral change with slab optical waveguide (SOWG) spectroscopy showed that 87.7% of the cyt.c adsorbed on the M-EG3-UPA modified ITO electrode remained on the ITO electrode. The SOWG absorption spectra corresponding to oxidized and reduced cyt.c were observed with setting the ITO electrode potential at 0.3 and -0.3 V vs. Ag/AgCl, respectively, while probing the DET reaction between cyt.c and ITO electrode occurred. The amount of cyt.c was evaluated to be about 19.4% of a monolayer coverage based on the coulomb amount in oxidation and reduction peaks on cyclic voltammetry (CV) data. The CV peak current maintained to be 83.4% compared with the initial value for a M-EG3-UPA modified ITO electrode after 60 min continuous scan with 0.1 V/s between 0.3 and -0.3 V vs. Ag/AgCl.

Analysis of the Interfacial Molecular Behavior of a Lubrication Film of n-Dodecane Containing Stearic Acid under Lubricating Conditions by Sum Frequency Generation Spectroscopy.

The molecular behavior of n-dodecane with added stearic acid at a friction interface was studied using sum frequency generation (SFG) spectroscopy and a tribometer. In the case of n-dodecane with stearic acid, under dynamic conditions, a strong peak from the symmetric stretching vibrational mode of methylene, which was not observed under static conditions, appears. However, this strong methylene peak was not observed in the case of only n-dodecane. The SFG spectrum in the C-H stretching mode region of n-dodecane-d26 with stearic acid in the dynamic condition was analogous to that in the static condition. These results indicate that the interfacial structure of stearic acid does not change under sliding condition. The n-dodecane on a stearic acid adsorption film is highly aligned. Moreover, from the sliding direction dependence of the SFG measurements, the molecular orientation of n-dodecane was deduced: n-dodecane on stearic acid adsorption films orient parallel to the sliding direction. These results have shown that the stearic acid adsorption film behaves as solid-like, which has also been mentioned in previous studies. Further, our results revealed a new function of stearic acid: the stearic acid adsorption film induces the formation of a well-defined n-dodecane interfacial structure and forces the n-dodecane molecules to orient along the sliding direction at the friction interface.

Rotational libration of a double-decker porphyrin visualized.

Scanning tunneling microscopy has revealed the reorientation of one of the macrocyclic rings of the double-decker porphyrin complex [Ce(TPP-Fc)(C(22)OPP)] [TPP-Fc = 5-(4-(4-ferrocenylphenylethynyl)phenyl)-10,15,20-triphenylporphyrin; C(22)OPP = 5,10,15,20-tetrakis(4-docosyloxyphenyl)porphyrin] by 90 degrees between scans when the other ring is fixed on a surface. This libration was evidenced by monitoring the location of the appended ferrocene unit, which functioned as a molecular beacon signaling its position.

Molecular motion of surface-immobilized double-decker phthalocyanine complexes.

The molecular motion of surface-immobilized double-decker phthalocyanine complexes was examined using STM. (C(8)OPc)(2)Ce (1), (C(12)OPc)(2)Ce (2), and (C(8)OPc)Ce(Pc) (3) double-decker complexes, of which two ligands contained Pc nuclei, formed well-ordered self-organized structures on their own. Square-shaped top Pc ligands were clearly observed for complexes 1, 2, and 3 even though free space presented around the top ligands caused by mixing the complexes with template molecules. However, the details of the shapes of the top ligands of complexes 1, 2, and 3 were changed by the surrounding environment. The surrounding environment was considered to have influenced the mobility of the top ligands. Another complex, (C(8)OPc)Ce(TPP) (4), had difficulty forming a self-organized structure by itself. Complex 4 could have been immobilized by coadsorbing on the substrate with the C(8)OPc template, but the intramolecular structure of the top ligands of complex 4 was difficult to observe. The results strongly suggested that combinations of molecules composed of double-decker complexes as well as the free space presented around a top ligand are important factors that control the molecular motion of immobilized double-decker complexes on solid surfaces.

Dual porosity single-walled carbon nanotube material.

We present a dual porosity CNT material with a seamless connection between highly porous aligned nanotubes and lowly porous closely packed nanotubes by using capillary action of liquids. Various approaches were developed to fabricate diverse structures using toothpicks, liquid thin films, bubbles, vapors, and superink jet printing. The dual porosity material showed low wear and was useful as a sliding electrical contact.

Splitting of the extraocular horizontal rectus muscle in congenital cranial dysinnervation disorders.

PURPOSE: To analyze the horizontal rectus extraocular muscles (EOMs) by orbital magnetic resonance imaging (MRI) in patients with congenital cranial dysinnervation disorders that arises from abnormal development of cranial nerve nuclei or their axonal connections. DESIGN: Case series, retrospective analysis. METHODS: The morphology of the horizontal rectus EOMs was analyzed in orbital MRI on 4 patients with congenital oculomotor palsy, 26 with congenital superior oblique palsy, and five with Duane syndrome. Orbital imaging was performed by 1.5 tesla (T) and 3T MRI, and quasi-coronal and sagittal images perpendicular and parallel to the long axis of the orbit were obtained at slice thicknesses of 3 and 2 mm. RESULTS: The horizontal rectus EOMs were split in 4 of the 35 patients (11%). Splitting was observed in 2 of the five patients (40%) with Duane syndrome, one of the 26 patients (4%) with congenital superior oblique palsy, and 1 of the 4 patients (25%) with oculomotor palsy, but in none of the 6 normal subjects and 12 patients with acquired cranial nerve palsy. CONCLUSION: Since splitting of the horizontal rectus EOMs was noted in patients with congenital dysinnervation disorders, including Duane syndrome, Sevel's theory that the horizontal rectus EOMs develop from the superior and inferior mesodermal complexes is considered to be reasonable.