Effects of V content on hydrogen storage properties of V–Ti–Cr alloys with high desorption pressure

Hydrogen storage is one of the most important issues to realize hydrogen society especially for on-board usage. Recently, high-pressure metal hydride (MH) tank attracts many attentions due to its high volumetric hydrogen storage density and relatively easy heat management. To emphasize its merits, further improvements of properties of MH, such as capacity, hydrogen desorption capability at low temperature and durability, are required. In this paper, V–Ti–Cr alloys of V-rich compositions were investigated with perspective of increasing of hydrogen desorption pressure and durability. In both of 60at%V–Ti–Cr and 80at%V–Ti–Cr alloys, good relationship between hydrogen desorption pressure and Ti content was observed. In comparing with 60at%V–Ti–Cr alloys, 80at%V–Ti–Cr alloys showed good durability. It is quite notable that relationship between limitation line (upper substitution limit of Ti by Cr without degradation of hydrogen capacity) and desorption pressure for V–Ti–Cr ternary system with V-rich composition is clarified. And also, it is revealed that in the case of V–Ti–Cr ternary system, not only Ti/Cr ratio but also V content is important factor to obtain alloys with high hydrogen desorption pressure. 75at%V–5at%Ti–Cr as-cast sample showed good durability, hydrogen desorption capability at low temperature and relatively high effective hydrogen capacity simultaneously.     

Photocatalytic oxidation of CO with various oxidants by Mo oxide species highly dispersed on SiO2 at 293 K

The photocatalytic oxidation of CO into CO₂ with oxidants such as NO, N₂O and O₂ proceeded efficiently on a Mo/SiO₂ with high Mo dispersion under UV light irradiation. It was found that the reaction rate greatly depended on the kind and concentration of the oxidant. Photoluminescence investigations reveal the close relationship between the reaction rate and the relative concentration of the photo-excited Mo⁶⁺-oxide species, i.e. charge transfer–excited–triplet state (Mo⁵⁺–O⁻)^*, under steady-state reaction conditions. Moreover, the photocatalytic oxidation of CO with O₂ in excess H₂ was carried out to test suitability for applications to supplying pure H₂. This reaction was seen to proceed efficiently on Mo/SiO₂ with a high CO conversion of 100% and CO selectivity of 99% after 180 min under UV light irradiation, showing higher photocatalytic performance than TiO₂ (P-25) photocatalyst. UV–vis, XAFS, photoluminescence and FT-IR investigations revealed that the high reactivity of the charge transfer–excited–triplet state (Mo⁵⁺–O⁻)^*, with CO as well as the high reactivity of the photoreduced Mo-oxide species (Mo⁴⁺-species) with O₂ to produce the original Mo-oxide species (Mo⁶⁺O²⁻), played a crucial role in the reactions.     

Oxygen permeation properties and surface modification of acceptor-doped CeO2/MnFe2O4 composites

The preparation and oxygen permeation properties of the (Ce_0.8Pr_0.2)O_2−δ − x vol% MnFe₂O₄ composites, where x = 0 to 35, have been investigated. The samples were prepared by the Pechini method. In the case of Ce_0.8Pr_0.2O_2−δ, an oxygen flux density of 6 μmol⋅cm⁻²⋅s⁻¹ (L = 0.0247 cm) and the maximum methane conversion of 50% were attained at 1000^∘C. Unlike composites consisting of Gd-doped CeO₂ and MnFe₂O₄, the oxygen permeability of the (Ce_0.8Pr_0.2)O_2−δ – x vol% MnFe₂O₄ composites was almost constant regardless of the volume fraction of MnFe₂O₄; however, the optimum volume fraction of MnFe₂O₄ was determined to be 5 to 25 in the context of the chemical and mechanical stabilities under methane conversion atmosphere. In addition, the surface modification of the (Ce_0.8Gd_0.2)O_2−δ – 15 vol% MnFe₂O₄ composite was performed by using the FePt nanoparticles. The catalyst loading of 2.8 mg/cm² on the both side of the 0.3 mm-thick (Ce_0.8Gd_0.2)O_2−δ – 15vol% MnFe₂O₄ composite increased the oxygen flux density from 0.30 to 0.76 μmol⋅cm⁻²⋅s⁻¹ in the case of He/air gradients; however, the effect seems to be reduced in the case of high oxygen flux density caused by a large pO₂ gradient. Moreover, the Langmuir-Blodgett film of the FePt nanoparticles were successfully prepared on the tape-cast (Ce_0.8Gd_0.2)O_2−δ – 15vol% MnFe₂O₄ composite. Hydrophobic treatments for the surface of the composite were crucial to achieve high transfer ratio for the deposition of the LB film.     

Ti−V−Cr BCC alloys system with high protium content

This paper aims to study the relationship between the protium absorption properties and alloy composition of Ti−V−Cr alloys. We studied the effects of composition of the alloys and the heat-treatment on the protium absorption-desorption properties of Ti−V−Cr alloys, and found that Ti−35V−40Cr alloys show 2.6 mass% protium capacity. The plateau pressure of the alloys increased with decreasing lattice constants, resulting from increasing Cr content. The main phase of the samples containing more than 15%V was a BCC phase in the cast state. These BCC phase alloys exhibited 2.4 mass% protium. It was also found that the heat-treatment was effective in stabilizing a BCC structure in Ti−V−Cr alloys with low V content. The alloy yields the high capacity of 3.0 mass% protium capacity, which will be the highest value at 313 K reported so far. The alloy will be promising since it contains a low amount of the expensive V element. This article based on a presentation made in the symposium “The 2nd KIM-JIM Joint Symposium: Hydrogen Absorbing Materials”, held at Hanyang University, Seoul, Korea, October 27–28 under the auspices of The Korean Institute of Metals and Materials and The Japan Institute of Metals.     

Synthesis of Nano-Sized Platinum Metal Particles on Ti-Containing Mesoporous Silica Using Microwave-Assisted Deposition Method

Using microwave-assisted deposition method the uniform and nano-sized platinum metal particles were prepared on the tetrahedrally coordinated Ti-oxide moieties isolated within the framework of mesoporous silica supports. The present nano-sized metal catalyst exhibited a higher activity for hydrogenation of nitrobenzene than the catalyst prepared by a conventional impregnation method.     

Development of a separable search-and-rescue robot composed of a mobile robot and a snake robot

Abstract

In this study, we propose a new robot system consisting of a mobile robot and a snake robot. The system works not only as a mobile manipulator but also as a multi-agent system by using the snake robot's ability to separate from the mobile robot. Initially, the snake robot is mounted on the mobile robot in the carrying mode. When an operator uses the snake robot as a manipulator, the robot changes to the manipulator mode. The operator can detach the snake robot from the mobile robot and command the snake robot to conduct lateral rolling motions. In this paper, we present the details of our robot and its performance in the World Robot Summit.     

Preferential Oxidation of CO Impurities in the Presence of H2 on NiO-Loaded and Unloaded TiO2 Photocatalysts at 293 K

The photocatalytic preferential oxidation of CO with O₂ in the presence of H₂ (photo-PROX) was found to proceed efficiently on the NiO-loaded TiO₂ (NiO/TiO₂) catalyst under UV light irradiation at 293 K. NiO/TiO₂ exhibited higher CO conversion as well as CO₂ selectivity for a photo-PROX reaction than the original unloaded TiO₂ (P-25). Various spectroscopic investigations have revealed that the small NiO clusters formed on TiO₂ play an important role in the enhancement of CO oxidation activity in this reaction.     

Fabrication of Hydrophobic Zeolites Using Triethoxyfluorosilane and their Application for Photocatalytic Degradation of Acetaldehyde

Hydrophobically modified zeolites were prepared using alkoxide reagent containing fluorine, triethoxyfluorosilane (TEFS). These zeolites have still maintained mesoporous structure and large surface area and showed more hydrophobic property compared with unmodified zeolite. Moreover surface modified zeolite prepared thus was applied as a support of TiO₂ photocatalyst for efficient adsorption and photocatalytic degradation of acetaldehyde diluted in air. With an increase in the grafted amount of TEFS reagent, the TiO₂ photocatalyst deposited on the modified zeolite showed greater photocatalytic activities for the degradation of acetaldehyde compared with that on unmodified zeolite due to its hydrophobic property.     

Simple Design of Hydrophobic Zeolite Material by Modification Using TEFS and its Application as a Support of TiO2 Photocatalyst

Through the simple process using alkoxide reagent containing fluorine, triethoxyfluorosilane (TEFS), hydrophobic mesoporous silica material (HMS) was prepared. The surface modified HMS have still maintained its mesoporous structure and large surface area and showed considerable hydrophobic property compared with non-modified HMS. Moreover the surface modified HMS was applied as a support of TiO₂ photocatalyst with the aim of the efficient degradation of organic pollutant in water. Due to the hydrophobic property, the fine TiO₂ photocatalyst particles were generated on the modified HMS and both the adsorption properties and photocatalytic activities for the degradation of 2-propanol diluted in water were dramatically increased.