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Platinum thin films on non-precious stable support materials are a promising form as oxygen reduction reaction (ORR) catalyst in the face of the tradeoff issue between the activity and durability for conventional Pt-based nanoparticles. However, support materials having high wettability against platinum are scarce and this type of catalyst has not been realized. In this study, we pursued to form a Pt thin film catalyst using diboride as a catalyst support. Platinum was deposited on NbB2 microparticles with the atomic layer deposition (ALD) method without exposing the NbB2 particles to air after the synthesis. The Pt/NbB2 catalysts with different Pt loadings were synthesized by changing the number of the ALD cycles, and the resulting catalyst surfaces were found to consist of Pt nanoparticles with the sizes of 2–3 nm uniformly dispersed on the NbB2 particles. The obtained highest values of the mass activity (MA) and area-specific activity (SA) were 165 A·g Pt−1 and 295 μA·cm Pt−2, respectively, which are lower than the values for conventional Pt/C catalysts. The effects of heat treatment of the Pt/NbB2 were also examined, and the surfaces of the Pt/NbB2 heat-treated at 800 °C were found to consist of flat Pt dense layers and bare NbB2 with the domain sizes larger than 10 nm. This observation suggests that a Pt thin film catalyst was successfully fabricated. The so-called CO annealing was applied to smooth the Pt surfaces and improve the activity, but the resulting catalyst was found to exhibit a lower ORR activity than the Pt/NbB2 catalyst before the heat treatment. Thus, further efforts are needed for practically utilizing the Pt/NbB2 catalyst with the unique Pt morphology.

The application of the water oxidation reaction to extract electrons from water molecules is important for the future sustainable synthesis of useful chemicals such as hydrogen and organic compounds. Therefore, a cost-effective oxygen evolution reaction (OER) in alkaline, neutral or acidic solution is required, based on the use of catalysts incorporating earth abundant elements. This work demonstrates that β-FeOOH(Cl) nanorod catalysts with high crystallinity and small size (an average diameter of 3 nm and a length of 15 nm) provided the best performance in the OER activity among Fe-based oxide and (oxy)hydroxide catalysts. The pristine β-FeOOH(Cl) nanorods with the high crystallinity are realized by a new process enabling one-pot, fast, and room temperature synthesis, which is the key to forming colloidal suspensions of the highly crystallized pure-phase β-FeOOH(Cl) nanorods. The versatility of this process also enabled doping of a wide variety of transition metals. Doping of Ni2+ (at 1.2 at%) improved the OER activity and shifted the threshold potential in the negative direction by 100 mV in an alkaline electrolyte, which was comparable to that of conventional IrOx colloidal nanoparticles.

This study focuses on the feasibility of using TMTiP (where TM is a 3d transition metal or a mixture of 3d transition metals, Cr, Mn, Fe, Co, and Ni; TiP denotes titanium phosphide) as the electrode material for the oxygen evolution reaction (OER) by systematic modification to the atomic ratio of the constituent metals. The catalytic activity of the electrode materials is expected to be governed by the d electrons of the transition metals; the electrical conductivity is provided by TiP even under highly acidic conditions. The OER activity followed a “volcano plot” as the TM was changed from Cr to Ni and assumed the maximum value for the composition cobalt titanium phosphide (CoTiP). The CoTiP electrode also exhibited excellent corrosion resistance and metallic conductivity (on the order of 10−6 Ω m) over the pH range 0–14. The OER activity of CoTiP was comparable to that of Pt but inferior to that of state-of-the-art IrO2 and RuO2.

A formation mechanism for monodispersed mesoporous silica spheres was investigated from the viewpoint of both particle growth and the progress of the condensation of the silica precursor. The particle growth of monodispersed mesoporous silica spheres was studied by TEM observation. The development of the mesopores was examined by in situ X-ray diffraction measurements. The condensation reaction of the silica precursor was analyzed by silicic acid titration and pH-conductivity measurements during the synthesis. It was found that small particles emerged suddenly after the commencement of the synthesis, and then the residual silica precursors reacted preferentially with the surface silanols on these existing particles. This led to the formation of monodispersed mesoporous silica spheres. Conversely, new small particles emerge throughout the synthesis in the case of a heterogeneous system. To confirm the preferential reaction of the silica precursors with the surface silanols, expansion of the existing particles was carried out by adding more silica precursor after the completion of the synthesis. It was found that the sizes of the particles were enlarged by the successive addition of more of the silica precursor. Surprisingly, the radial alignment of the hexagonal mesopores was still retained in the expanded particles. In addition, by the addition of a different silica precursor to the initial one, highly monodispersed core/shell mesoporous silica spheres possessing a hydrophilic core and a hydrophobic shell were successfully obtained for the first time.

Mono-dispersed mesoporous silica spheres with ordered hexagonal regularity were synthesized from tetramethoxysilane and dodecyltrimethylammonium bromide as a surfactant under very specific conditions. By adjusting the optimum concentrations of the reactants, silica particles with diverse morphology were obtained at higher initial concentrations. Dilution of the reactants led to the formation of silica spheres with various sizes and relatively less mesoporous regularity. Mono-dispersed silica spheres could not be obtained when hexadecyltrimethylammonium bromide and tetradecyltrimethylammonium bromide were used as surfactants.

A novel route to produce nanocolloid of single nano-sized particles was developed. Pd particles are stirred in water. Then laser ablation was conducted using a second harmonic light from Nd:YAG laser system focused on the air–liquid interface. We could obtain yellow nanocolloid. Pd nanoparticles have been stably dispersed in water without any chemical reagents for >1 year. Large absorption below 500 nm could be confirmed. The surface condition of colloidal particles was analyzed by X-ray photoelectron spectroscopy (XPS) of dried particles on Si wafer and pH measurement of nanocolloid. The range of pH value of nanocolloid was from 2 to 3. On the other hand, NO3 and NO2 were detected on the dried sample by XPS spectrum. In addition, transmission electron microscopy and dynamic light scattering (DLS) methods revealed a very narrow size distribution. The size distribution in the range from 0.5 to 1.5 nm was confirmed by DLS method. The size distribution and stability of Pd nanocolloid could be explained by chemical reaction between air, water, and Pd target due to excitation by pulsed laser irradiation and production of active particles in the laser-induced plasma.

The synthetic conditions of highly ordered and thermally stable mesoporous molecular sieves from a layered silicate kanemite are established. We divided the formation process of the mesoporous materials from kanemite into two elemental processes: i) exchange of Na+ in the interlayer of kanemite for alkyltrimethylammonium cations and ii) condensation of silicates and formation of a three dimensional silicate framework. Higher pH (over 11.5) at the cation-exchange process and the subsequent pH adjustment at 8.5 at the condensation process were best suited for the formation of mesoporous products with high regularity and thermal stability. Removal of partially dissolved kanemite during the cation-exchange process avoided the formation of amorphous materials as a by-product. Structures of some intermediate silicate/surfactant complexes supported the proposed folded sheets mechanism for the formation of the mesoporous molecular sieves. Syntheses by using alkyltrimethylammonium with different alkyl-chain length...

Catalyst poisoning by specific adsorption of the sulfonic acid anion of ionomers has been known as one of the main performance-limiting factors of PEFCs. In a recent study, it was reported that the catalyst poisoning can be suppressed by using a mesoporous carbon (mesoporous carbon nano-dendrites) as a cathode catalyst support [1]. Here, we present that a similar effect can be obtained by using a MgO-templated mesoporous carbon [2] having meso-pores the sizes of which are more-systematically controllable by changing the size of the MgO templates than for conventional carbon supports. An MgO-templated carbon denoted as CNovel® was purchased from Toyo Tanso Inc. The mean diameter of its mesopores is ca. 5 nm (the template MgO size was 5 nm). The sample was graphitized by a heat treatment at 2,100 °C for improving the chemical stability under electrochemical conditions and was crushed by a bead mill to form secondary particles smaller than hundreds nm in size. The obtained powder was immersed in 1 M HNO3 at 80 °C for 1 h to introduce hydrophilic surface groups for facilitating Pt deposition. After thoroughly washing it with pure water, platinum nanoparticles were deposited in aqueous media by using hexahydroxy-platinate as a platinum source. The ORR activity of the prepared catalyst was evaluated by the thin-film RDE method (without ionomers) in aqueous media (0.1 M HClO4) and in MEAs prepared with a Nafion® ionomer (I/C=1.0). The results were compared those of Pt/Vulcan. Figures 1a and 1b show that TEM images of the catalysts. Platinum particles of ca. 2 nm are observed on both the carbons. While Pt/Vulcan shows platinum particles only on the outer edge of the carbon particle, Pt/CNovel shows platinum particles not only on the outer edge but also on the mesopores inside the carbon particle. Figure 1c shows the I-V curves of MEAs using Pt/CNovel and Pt/Vulcan. Pt/CNovel exhibits higher cell-voltage than Pt/Vulcan in the low current density region. This result indicates that the former has a higher ORR activity than the latter as specifically indicated in the specific activities at 0.9 V shown in Figure 1d. The trend is, however, opposite in the RDE measurements while the specific activities for both samples by RDE are higher than those measured by the MEAs. These results indicate that the Pt/CNovel suffers less catalyst poisoning by the sulfonic acid anion than Pt/Vulcan in MEAs probably because the anion linked to the ionomer cannot reach the surfaces of the Pt nanoparticles inside the mesopores of CNovel while all Pt nanoparticles on Vulcan® can be reached by the ionomer. References [1] M. Hori, et al., 225th ECS Meeting Abstract, #1500 (2013) [2] T. Morishita, et al., Carbon, 48, 2690 (2010) Figure 1

Oligosilanes bridging microgaps between silicon microcrystallites were investigated as a possible model for the origin of the intense visible photoluminescence of porous silicon by means of the semiempirical molecular‐orbital method. The incomplete structural relaxation of the oligosilane bridge after the photoexcitation was found to be a key factor to give the visible photoluminescence. The calculated structure‐insensitive photoexcitation energy around 3.3 eV and the structure‐sensitive light emission energy around 1.2–2.1 eV are consistent with the experimental evidence. The sufficient transition probabilities between the concerning electronic states support the high efficiency of photoluminescence. Durabiliy of the structure under the photoexcitation was also suggested. The model is valid even if the silicon microcrystallites are partly or thoroughly replaced by silicon oxides particles as is more realistic for the porous silicon exposed to the air.

The crystal structure and the electronic structure of crystalline C 60 grown from a benzene solution have been studied by transmission electron microscopy and energy loss spectroscopy. Electron diffraction patterns and high-resolution images reveal an hcp structure ( a = 1.01±0.01 nm , c = 1.65±0.02 nm ) with stacking disorders. Electron energy loss spectra in a low-loss region revealed not only two collective excitations at 6.5 and 26 eV but also several single-electron excitations. From carbon K-shell excitation, spectral information on unoccupied π ∗ and σ ∗ bands has been obtained.

Changes in the microstructure of diesel soot during oxidation in air were examined by means of an analytical electron microscope. The soot was sampled using a stainless-steel mesh placed in an engine exhaust pipe. The samples at 25, 50, and 75 wt% burnoff were obtained by controlling the holding time in an electric furnace at 500°C. In the early stage of oxidation, an occluded “SOF (soluble organic fraction)” within the soot particles is released and the soot particles take on a porous structure. Also, layer planes of crystallites within the soot particles grow successively and are arranged, a turbostratic structure. In the last stage of oxidation, the size of the layer planes of the crystallites in the soot particles does not become smaller, but crystallites at the outermost shell of the soot particles flake off instead, reducing the size of the particles. That is, the oxidative disappearance of the soot particles is concluded to involve a disintegration and stripping of the outer layer, induced by strain energy in the layer plane that accompanies the growth of the crystallite layer under high temperature.

SiO2/poly-Si/SiO2 double-barrier structures fabricated by radio-frequency magnetron sputtering are shown to exhibit negative differential resistance (NDR) that is attributed to resonant tunneling (RT) at low temperatures. An annealing process conducted after the multilayer deposition is found to effectively yield stable NDR. Five percent of all of the fabricated devices exhibit clear NDR below 50 K. Other devices with the same multilayered structure exhibit staircase-like current–voltage curves caused by the Coulomb blockade (CB) or by interplay between the RT and CB. The requisites of the poly-Si layer microstructures for the realization of stable RT are elucidated.

Particle size development of monodispersed mesoporous silica spheres (MMSS) was investigated by laser scattering measurement, TEM and XRD in situ. Smaller particles suddenly appeared after the commencement of the experiment, then growing homogeneously to larger particles. It is assumed that residual silica precursors in solution preferentially reacted with existing particle surface silanol, preventing generation of new particles. This leads to the formation of monodispersed particles. Based on the mechanism, monodispersed mesoporous silica spheres with core/shell structure have been newly synthesized.

A new rubber recycling technology to produce a thermoplastic elastomer (TPE) based on ethylenepropylene-diene rubber (EPDM) waste was developed. In this technology, the developed process consists of devulcanization of EPDM waste, blending of the devulcanized EPDM and polypropylene (PP), aid dynamic vulcanization of the rubber- component. All three are set up in as a continuous process in which the Recycled Rubber based Thermoplastic Elastomer (which is indicated as "RR-TPE" henceforth) is finally obtained. The RR-TPE exhibits elasticity and mechanical properties similar to those of commercial Thermoplastic olefins (TPO). These properties may be due to a suitably formed phase structure. Automotive parts are being developed and are going to be produced with the RR-TPE manufactured by this new technology. This technology will contribute to both protecting the environment and saving resources.

The oxygen content of the low Tc phase was varied by annealing in N2 and O2 at 500–750 °C. The oxygen unloading increased the Tc up to 100 K and the length of c-axis by 0.01nm. The associated structural change was examined by X-ray diffraction, XPS, and HRTEM. XPS measurements were performed on the clean fracture surface. No major difference was detected on Bi and Cu spectra, indicating that the change of oxygen content was too small to cause detectable change in the valence of Bi and Cu ions. High resolution TEM showed that the average period of modulation in Bi-O layer was unvaried but the modulation was locally disordered by oxygen unloading. These results strongly indicate that oxygen unloading takes place from the Bi-O layer and the Tc of low Tc phase is mainly controlled by the oxygen in Bi-O layer. Preliminary EXAFS data were also consistent with this idea.

The single-shot creation of tadpolelike silicon nanoparticles constructed with multi-crystalline heads and amorphous tails by a high brightness fs-pulse laser was demonstrated. This is also the first demonstration of the creation of a nanosized connection of multicrystalline silicon with amorphous silicon. This result should expand the creation of new materials by a laser ablation using a high-intensity fs laser, and the created silicon nanoparticles can be applied to scientific and industrial fields.

The properties and structure of the low Tc phase in BrSrCaCuO superconductors was greatly affected by the oxygen content, which was varied by annealing specimens in various atmospheres. The Tc of low Tc phase increased up to 100 K by annealing in nitrogen. Annealing in nitrogen caused the reversible weight loss of about 0.2% and the increase in the c-axis by 0.01 nm. The variation of microstructure was examined by TEM. The average period of modulation in Bi-O layer was found to be unvaried (2.7 nm) but the detailed local structure seemed to be disordered by oxygen evolution.

Single‐crystalline aluminum layer buried in α‐Al2O3 has been synthesized by high‐dose ion implantation of aluminum ions at an elevated temperature. It has been revealed by a high‐resolution transmission electron microscope that the aluminum layer has interfaces which are remarkably smooth and abrupt within a few atomic layers. This observation is comparable to that in mesotaxy of silicides buried in silicon.

In Auger depth profiling in combination with ion sputtering, use of an insular sample has improved the depth resolution and has enabled pinpoint analysis without extending measurement time. An island capped with an erosion-resistant film remains on the substrate after chemical etching. When the island is prepared to be smaller than the area subjected to ion irradiation, no crater or its sidewall appears during depth profiling. It is demonstrated that in the determination of depth resolution, surface roughening owing to sputter deposition from the sidewall of a crater plays a key role, in addition to the interference by signals from a sidewall.

Crystallites of C60/C70 mixture and pure C60 have been produced from benzene solution by evaporating the benzene solvent. The new forms of solid carbon have been examined by electron microscopy with particular attention to the structure of crystallites with platelet shape. Electron diffraction patterns and high-resolution images reveal that they have an hcp structure (a=10.1±0.1 Å, c=16.5±0.2 Å) with stacking faults of molecular layers perpendicular to the c-axis.

The shape of gold crystals inside sapphire has been studied by transmission electron microscopy. 400 keV gold ions were implanted into sapphire (α-Al2O3) at a substrate temperature of 1200°C. The gold ions precipitate as small crystals, which have an ordinary f.c.c. structure and dimensions less than 60 nm. The small gold crystals clearly have faceted outlines. The sides of the outlines are parallel to low-index crystal-planes of sapphire. It has therefore been concluded that the shape of the gold crystals is characterized by the foreign crystal (i.e., sapphire), and that the shape should be a tetradecahedron which consists of two {0001} and twelve planes of sapphire.

The interface of the Zr/sapphire implanted with N+ ions were examined by RBS and cross-sectional TEM observations. The ion implantation induced the interdiffusion of atoms at the interface and the clear border-line between the Zr film and sapphire was found to disappear. The thickness of the diffusion layer was estimated to be about 10 nm at the interface of the Zr/sapphire implanted with N+ ions to the dose of 2×1017/cm2.