Susumu Tsubota

Bio: Susumu Tsubota is an academic researcher from National Institute of Advanced Industrial Science and Technology. The author has contributed to research in topics: Catalysis & Propylene oxide. The author has an hindex of 43, co-authored 87 publications receiving 6640 citations. Previous affiliations of Susumu Tsubota include Industrial Research Institute & Japanese Ministry of International Trade and Industry.

Photoassisted hydrogen production from a water-ethanol solution: a comparison of activities of AuTiO2 and PtTiO2

Abstract: A comparison of the photocatalytic activity for H 2 generation between AuTiO 2 and PtTiO 2 has been made. The deposition of Au and Pt was carried out using TiO 2 powders in aqueous suspensions containing HAuCl 4 ·4H 2 O or H 2 PtCl 6 ·6H 2 O by deposition-precipitation (DP), impregnation (IMP), photodeposition (FD) and, in the case of Au, by mixing TiO 2 with colloidal gold suspensions (MIX). The main reaction products obtained from the irradiation of an aqueous 5 M C 2 H 5 OH suspension containing AuTiO 2 or PtTiO 2 were hydrogen, methane, carbon dioxide and acetaldehyde. Small amounts of acetic acid were also detected. The overall activity of Au samples was generally about 30% lower than that of Pt samples. The activity of Au samples strongly depended on the method of preparation and decreased in the order AuTiO 2 -FD>AuTiO 2 -DP>AuTiO 2 -IMP>AuTiO 2 -MIX. The activities of the platinum samples were less sensitive to the preparation method and decreased in the order PtTiO 2 -FD>PtTiO 2 -DP≈PtTiO 2 -IMP. Gold and platinum precursors calcined in air at 573 K showed the highest activity towards H 2 generation, followed by a decline in activity with increasing calcination temperature. The H 2 yield was found to be dependent on the metal content on TiO 2 and showed a maximum in the ranges 0.3–1 wt.% Pt and 1–2 wt.% Au. The exposed surface area of gold had only a small influence on the rate of hydrogen generation. On the other hand, the rate of H 2 production was strongly dependent on the initial pH of the suspension. pH values in the range 4–7 gave better yields, whereas highly acidic and basic suspensions resulted in a considerable decrease in the H 2 yield.

The influence of the preparation methods on the catalytic activity of platinum and gold supported on TiO2 for CO oxidation

Abstract: The influence of the preparation methods on the catalytic activity for CO oxidation was markedly large for Au-TiO2 and negligible for Pt-TiO2 catalysts. Platinum and gold were deposited on TiO2 by deposition-precipitation (DP), photodeposition (FD) and impregnation (IMP). The DP method gave the most active catalysts for both Pt and Au. Gold catalysts prepared by DP were active at temperatures below 273 K and showed a much greater activity than Pt catalysts.

Catalysis by Gold Nanoparticles: Epoxidation of Propene

Abstract: Supported nano-gold catalysts have attracted rapidly growing interest due to their potential applicability to various reactions of industrial and environmental significance. In this article, we focus on the advances related to the direct vapor-phase oxidation of propene to propene oxide in the presence of molecular oxygen and hydrogen over gold catalysts supported on Ti-incorporated silica materials prepared by different methods. The importance of catalyst preparation and pretreatment method, nature of support material, Au particle size and loading amount is emphasized. Possibilities to enhance the catalyst performance by using promoters and by silylation are also discussed.

Gold nanoparticles: assembly, supramolecular chemistry, quantum-size-related properties, and applications toward biology, catalysis, and nanotechnology.

Abstract: Although gold is the subject of one of the most ancient themes of investigation in science, its renaissance now leads to an exponentially increasing number of publications, especially in the context of emerging nanoscience and nanotechnology with nanoparticles and self-assembled monolayers (SAMs). We will limit the present review to gold nanoparticles (AuNPs), also called gold colloids. AuNPs are the most stable metal nanoparticles, and they present fascinating aspects such as their assembly of multiple types involving materials science, the behavior of the individual particles, size-related electronic, magnetic and optical properties (quantum size effect), and their applications to catalysis and biology. Their promises are in these fields as well as in the bottom-up approach of nanotechnology, and they will be key materials and building block in the 21st century. Whereas the extraction of gold started in the 5th millennium B.C. near Varna (Bulgaria) and reached 10 tons per year in Egypt around 1200-1300 B.C. when the marvelous statue of Touthankamon was constructed, it is probable that “soluble” gold appeared around the 5th or 4th century B.C. in Egypt and China. In antiquity, materials were used in an ecological sense for both aesthetic and curative purposes. Colloidal gold was used to make ruby glass 293 Chem. Rev. 2004, 104, 293−346

Heterogeneous photocatalyst materials for water splitting

Abstract: This critical review shows the basis of photocatalytic water splitting and experimental points, and surveys heterogeneous photocatalyst materials for water splitting into H2 and O2, and H2 or O2 evolution from an aqueous solution containing a sacrificial reagent Many oxides consisting of metal cations with d0 and d10 configurations, metal (oxy)sulfide and metal (oxy)nitride photocatalysts have been reported, especially during the latest decade The fruitful photocatalyst library gives important information on factors affecting photocatalytic performances and design of new materials Photocatalytic water splitting and H2 evolution using abundant compounds as electron donors are expected to contribute to construction of a clean and simple system for solar hydrogen production, and a solution of global energy and environmental issues in the future (361 references)

Semiconductor-based Photocatalytic Hydrogen Generation

Abstract: 2.3. Evaluation of Photocatalytic Water Splitting 6507 2.3.1. Photocatalytic Activity 6507 2.3.2. Photocatalytic Stability 6507 3. UV-Active Photocatalysts for Water Splitting 6507 3.1. d0 Metal Oxide Photocatalyts 6507 3.1.1. Ti-, Zr-Based Oxides 6507 3.1.2. Nb-, Ta-Based Oxides 6514 3.1.3. W-, Mo-Based Oxides 6517 3.1.4. Other d0 Metal Oxides 6518 3.2. d10 Metal Oxide Photocatalyts 6518 3.3. f0 Metal Oxide Photocatalysts 6518 3.4. Nonoxide Photocatalysts 6518 4. Approaches to Modifying the Electronic Band Structure for Visible-Light Harvesting 6519

The bactericidal effect of silver nanoparticles

Abstract: Nanotechnology is expected to open new avenues to fight and prevent disease using atomic scale tailoring of materials. Among the most promising nanomaterials with antibacterial properties are metallic nanoparticles, which exhibit increased chemical activity due to their large surface to volume ratios and crystallographic surface structure. The study of bactericidal nanomaterials is particularly timely considering the recent increase of new resistant strains of bacteria to the most potent antibiotics. This has promoted research in the well known activity of silver ions and silver-based compounds, including silver nanoparticles. The present work studies the effect of silver nanoparticles in the range of 1-100 nm on Gram-negative bacteria using high angle annular dark field (HAADF) scanning transmission electron microscopy (STEM). Our results indicate that the bactericidal properties of the nanoparticles are size dependent, since the only nanoparticles that present a direct interaction with the bacteria preferentially have a diameter of approximately 1-10 nm.