Papers - IKEDA Shigeru
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Transition metal doped TiO2: physical properties and photocatalytic behaviour Reviewed
Di Paola, A.; Ikeda, S.; Marci, G.; Ohtani, B.; Palmisano, L.
INTERNATIONAL JOURNAL OF PHOTOENERGY 3 ( 4 ) 171 - 176 2001.12
Joint Work
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Photocatalytic activity of transition-metal-loaded titanium(IV) oxide powders suspended in aqueous solutions: Correlation with electron-hole recombination kinetics Reviewed
S Ikeda, N Sugiyama, B Pal, G Marci, L Palmisano, H Noguchi, K Uosaki, B Ohtani
PHYSICAL CHEMISTRY CHEMICAL PHYSICS 3 ( 2 ) 267 - 273 2001.1
Joint Work
Authorship：Lead author Publisher：ROYAL SOC CHEMISTRY
Photocatalytic reactions by transition-metal (V, Cr, Fe, Co, Cu, Mo, or W) loaded TiO2 (M-TiO2) powders suspended in aqueous solutions of methanol, (S)-lysine (Lys), or acetic acid were investigated. The photoactivities of various samples were compared with the rate constant (k(r)) of recombination of photoexcited electrons and positive holes determined by femtosecond pump-probe diffuse reflection spectroscopy (PP-DRS). As a general trend, increased loading decreased the rate of formation of the main products (H-2, pipecolinic acid (PCA), and CO2) under UV (> 300 nm) irradiation, and the effect became more intense on increasing the loading. In PP-DRS, these M-TiO2 gave similar decays of absorption at 620 nm arising from excitation by a 310 nm pulse (< 100 fs). The second-order rate constant (k(r)) markedly increased with loading, even at a low level (0.3%) and further increased with an increase in loading up to 5%. The photocatalytic activity of platinized M-TiO2 for H-2 and PCA production under deaerated conditions depended strongly on k(r), but the relation between k(r) and the rate of CO2 production by unplatinized M-TiO2 under aerated conditions was ambiguous; other factor(s) might control the rate of the latter. These different k(r) dependences of photoactivity on the reaction kinetics governed by e(-)-h(+) recombination were attributed to the presence of O-2 and Pt deposits. A simple kinetic model to explain the overall rate of these photocatalytic reactions is proposed, and the effect of recombination kinetics on photoactivity is discussed.
DOI： 10.1039/b008028o
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Transition metal doped TiO2: physical properties and photocatalytic behaviour
A. Di Paola, S. Ikeda, G. Marci, B. Ohtani, L. Palmisano
INTERNATIONAL JOURNAL OF PHOTOENERGY 3 171 - 176 2001
Publisher：HINDAWI PUBLISHING CORPORATION
Two probe photocatalytic reactions, i.e. ethanoic acid and 4-nitrophenol photooxidation, were carried out in different experimental conditions by using suspensions of transition metal (Co, Cr, Cu, Fe, Mo, V and W) doped polycrystalline TiO2 powders in aqueous systems. A beneficial influence of the presence of metal species was observed only with the samples containing copper and tungsten. In particular, the TiO2/Cu powders showed to be more photoactive of bare TiO2 for the ethanoic acid oxidation while the TiO2/W samples were more efficient for 4-nitrophenol degradation. A tentative interpretation is provided on the basis of the values of the points of zero charge of the powders and of the rate constants of recombination of photogenerated electrons and holes, determined by femtosecond pump-probe diffuse reflectance spectroscopy (PP-DRS).
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Mechano-catalytic overall water splitting on some mixed oxides Reviewed
G Hitoki, T Takata, S Ikeda, M Hara, JN Kondo, M Kakihana, K Domen
CATALYSIS TODAY 63 ( 43135 ) 175 - 181 2000.12
Joint Work
Publisher：ELSEVIER SCIENCE BV
Simple transition metal oxides such as NiO, Co3O4, Fe3O4 and Cu2O were found to catalytically decompose water into H-2 and O-2 by mechanical energy, The reaction is regarded as "mechano-catalytic'' overall water splitting" and is a quite novel catalytic reaction. In this paper, some,general aspects on the mechano-catalytic overall water splitting are reviewed on simple oxides. In addition, recent results on the mechano-catalytic activity of a groups of mixed oxides, wolramite-type oxides with a formula of ABO(4) (A = Fe, Co, Ni and Cu, etc., B = W, Mo), are shown. AWO(4) (A = Fe, Co, Ni and Cu) decomposed water into H-2 and O-2 under the supply of mechanical energy, indicating that mechano-catalytic overall water splitting proceeded on wolframite-type compounds containing 3d-transition metals. AMoO(4) (A = Fe, Co, Ni) also decomposed water into H-2 and O-2 under supply of mechanical energy. The reaction properties on wolframite-type oxides are discussed. (C) 2000 Elsevier Science B.V. All rights reserved.
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Shape- and size-selective photocatalytic reactions by layered titanic acid powder suspended in deaerated aqueous alcohol solutions Reviewed
B Ohtani, S Ikeda, H Nakayama, S Nishimoto
PHYSICAL CHEMISTRY CHEMICAL PHYSICS 2 ( 22 ) 5308 - 5313 2000.11
Joint Work
Publisher：ROYAL SOC CHEMISTRY
Protonic titanate of H(x)Ti(2-x/4)Z(x/4)O(4).H2O (HLe; x similar or equal to0.7, Z=vacancy) powder of a layered crystal structure was prepared, suspended in aqueous alcoholic solutions and photoirradiated by light of wavelength > 300 nm at room temperature under a deaerated atmosphere. HLe showed photocatalytic activity of H-2 production, similar to ordinary titanium(IV) oxide powders. The rate and time course of H-2 evolution by HLe depended strongly on the kind of alcohol. Detailed investigation revealed that the photocatalytic activity was regulated by the shape and size of the alcohol, due to the selection of adsorption at the interlayer of HLe.
DOI： 10.1039/b006497l
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Phase-boundary catalysis: a new approach in alkene epoxidation with hydrogen peroxide by zeolite loaded with alkylsilane-covered titanium oxide Reviewed
H Nur, S Ikeda, B Ohtani
CHEMICAL COMMUNICATIONS pp2235-2236 ( 22 ) 2235 - 2236 2000.11
Joint Work
Publisher：ROYAL SOC CHEMISTRY
An NaY zeolite, modified with partly alkylsilane-covered titanium oxide and located at the boundary between aqueous and organic phases (a phase-boundary catalyst), acts as a catalyst for alkene epoxidation without stirring or the addition of a co-solvent to drive liquid-liquid phase transfer.
DOI： 10.1039/b006207n
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Synthesis of (H3O)TiNbO5 center dot 0.26H(2)O via hydronium (H3O+) ion-exchange reaction and its photocatalytic activity for H-2 evolution from aqueous methanol solution Reviewed
H Takahashi, M Kakihana, Y Yamashita, K Yoshida, S Ikeda, M Hara, K Domen
PHYSICAL CHEMISTRY CHEMICAL PHYSICS 2 ( 19 ) 4461 - 4464 2000.10
Joint Work
Publisher：ROYAL SOC CHEMISTRY
(H3O)TiNbO5. 0.26H(2)O powder was prepared from layered titanoniobate, KTiNbO5, using an ion-exchange reaction in acidic aqueous solution. X-ray diffraction, thermogravimetry-differential thermal analysis, energy-dispersive X-ray analysis and infrared spectral data gave the first experimental evidence that the so-called proton-exchanged form HTiNbO5 involves hydrated water or hydrated hydronium ion. The intercalation of water or hydronium ion in KTiNbO5 was not achieved by the conventional high-temperature solid-state reaction method but by the low-temperature polymerizable complex (PC) method. While KTiNbO5 via the PC route, combined with Pt, showed only little improvement of the photocatalytic activity with respect to H-2 evolution from aqueous methanol solution, the water or hydronium ion intercalated species, (H3O)TiNbO5. 0.26H(2)O, with Pt loading, showed much higher activities than the others species studied by an order of magnitude.
DOI： 10.1039/b003808n
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Mechano-catalytic overall water-splitting into hydrogen and oxygen on some metal oxides Invited Reviewed
K Domen, S Ikeda, T Takata, A Tanaka, M Hara, JN Kondo
APPLIED ENERGY 67 ( 43102 ) 159 - 179 2000.9
Joint Work
Publisher：ELSEVIER SCI LTD
This is a novel way to generate hydrogen from pure water by converting mechanical energy to chemical energy. The phenomenological aspects of the mechano-catalytic overall water-splitting are reviewed, and the basic feature of the catalytic process is clearly established. The estimation of the conversion from mechanical to chemical energy is also shown. Experimental results. carried out to reveal the mechanism of the mechano-catalytic reaction are described. (C) 2000 Elsevier Science Ltd. All rights reserved.
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Mechano-catalytic overall water splitting on some mixed oxides Reviewed
G Hitoki, T Takata, S Ikeda, M Hara, JN Kondo, M Kakihana, K Domen
CATALYSIS TODAY 200 ( 43102 ) 255 - 262 2000.8
Joint Work
Publisher：ELSEVIER SCIENCE BV
Simple transition metal oxides such as NiO, Co3O4, Fe3O4 and Cu2O were found to catalytically decompose water into H-2 and O-2 by mechanical energy, The reaction is regarded as "mechano-catalytic'' overall water splitting" and is a quite novel catalytic reaction. In this paper, some,general aspects on the mechano-catalytic overall water splitting are reviewed on simple oxides. In addition, recent results on the mechano-catalytic activity of a groups of mixed oxides, wolramite-type oxides with a formula of ABO(4) (A = Fe, Co, Ni and Cu, etc., B = W, Mo), are shown. AWO(4) (A = Fe, Co, Ni and Cu) decomposed water into H-2 and O-2 under the supply of mechanical energy, indicating that mechano-catalytic overall water splitting proceeded on wolframite-type compounds containing 3d-transition metals. AMoO(4) (A = Fe, Co, Ni) also decomposed water into H-2 and O-2 under supply of mechanical energy. The reaction properties on wolframite-type oxides are discussed. (C) 2000 Elsevier Science B.V. All rights reserved.
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A study of mechano-catalysts for overall water splitting Reviewed
M Hara, M Komoda, H Hasei, M Yashima, S Ikeda, T Takata, JN Kondo, K Domen
JOURNAL OF PHYSICAL CHEMISTRY B 104 ( 4 ) 780 - 785 2000.2
Joint Work
Publisher：AMER CHEMICAL SOC
Mechano-catalytic overall water splitting on Cu2O, NiO, and CO3O4 was investigated in order to reveal the reaction mechanism. The experimental results indicated that metallic elements of these oxides were generated during the reaction. Also, elemental metals Cu, Ni, and Co were oxidized into Cu2O, NiO, and Co3O4, respectively, when water was reduced into Hz by the metal powders under the same reaction condition. The metallic particles covered with the metal oxides evolved both O-2 and H-2 These results suggest that a redox reaction between the metal and metal oxide may be responsible for H-2 and O-2 formation of the mechano-catalytic overall water splitting.
DOI： 10.1021/jp993441h
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Mechano-catalytic overall water splitting (II) nafion-deposited Cu2O Reviewed
M Hara, H Hasei, M Yashima, S Ikeda, T Takata, JN Kondo, K Domen
APPLIED CATALYSIS A-GENERAL 190 ( 43102 ) 35 - 42 2000.1
Joint Work
Publisher：ELSEVIER SCIENCE BV
Some modifications of a mechano-catalyst, Cu2O, and optimization of the reaction conditions were attempted to improve its activity for mechano-catalytic overall water splitting. The rates of evolution of H-2 and O-2 were improved by deposition of nafion onto Cu2O and the choice of an appropriate stirring rod. The irradiation of visible light (lambda > 550 nm) was found to maintain the activity in the time course, which gradually decreased without irradiation. (C) 2000 Elsevier Science B.V. All rights reserved.
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Mechano-catalytic overall water splitting for hydrogen production Reviewed
K Domen, S Ikeda, T Takata, A Tanaka, A Hara, JN Kondo
HYDROGEN ENERGY PROGRESS XIII, VOLS 1 AND 2, PROCEEDINGS 253 - 257 2000
Publisher：INT ASSOC HYDROGEN ENERGY
Mechano-catalytic overall water splitting is a novel way to generate hydrogen from pure water by converting mechanical energy to chemical energy with the aid of some metal oxides. The phenomenological aspects of the mechano-catalytic overall water splitting are reviewed, and the basic feature of the catalytic process is clearly established. Some experimental results for revealing the reaction mechanism are also described.
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Mechano-catalysis - a novel method for overall water splitting Reviewed
S Ikeda, T Takata, M Komoda, M Hara, JN Kondo, K Domen, A Tanaka, H Hosono, H Kawazoe
PHYSICAL CHEMISTRY CHEMICAL PHYSICS 1 ( 18 ) 4485 - 4491 1999.9
Joint Work
Authorship：Lead author Publisher：ROYAL SOC CHEMISTRY
A novel finding of mechano-catalytic overall water splitting by metal oxides, a way to produce hydrogen by water decomposition, is reported. It was clearly revealed that some simple and mixed oxide powders such as NiO, Co3O4, Cu2O, Fe3O4, and CuMO2 (M=Al, Fe, Ga), when suspended in distilled water by magnetic stirring, decompose water into H-2 and O-2 catalytically. The observed mechano-catalytic overall water splitting was cycled by the conversion of mechanical energy supplied by rubbing these oxide powders against the bottom wall of the reaction vessel with the stirring rod. Typical efficiency of the mechanical-to-chemical energy conversion was estimated to be 4.3% (for NiO).
DOI： 10.1039/a903543e
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Novel methods for preparation of ion-exchangeable thin films Reviewed
R Abe, S Ikeda, JN Kondo, M Hara, K Domen
THIN SOLID FILMS 343 156 - 159 1999.4
Joint Work
Publisher：ELSEVIER SCIENCE SA
Ion-exchangeable thin films of inorganic compounds were prepared by the soft-chemical method. A thin him composed of a layered titanate was prepared by exfoliation of the layered compound H(+)/Cs(x)Ti((2-x/4))square(x/4),O(4) in an aqueous ethyl amine solution. The exfoliated titanate sheets were easily oriented on a substrate by means of spin-coating. A layered potassium niobate, K(4)Nb(6)O(17), was made into a thin film from suspension of fine particles prepared by wet-grinding of the original K(4)Nb(6)O(17) powder. After calcination at 1073 K, the K(4)Nb(6)O(17) thin him had a well-ordered layered structure with the b-axis perpendicular to the substrate surface. The ion-exchange property of those films enabled the intercalation of other cations without destroying the layered structures. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.
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Synthesis of NiO-loaded KTiNbO5 photocatalysts by a novel polymerizable complex method Reviewed
H Takahashi, M Kakihana, Y Yamashita, K Yoshida, S Ikeda, M Hara, K Domen
JOURNAL OF ALLOYS AND COMPOUNDS 285 ( 43102 ) 77 - 81 1999.3
Joint Work
Publisher：ELSEVIER SCIENCE SA
A polymerizable complex (PC) technique was utilized to prepare high-purity stoickiometric KTiNbO5 at reduced temperatures. Heating of a mixed solution of citric acid (CA), ethylene glycol (EG), and K, Ti and Nb ions with a molar ratio of CA:EG:K:Ti:Nb=15:60:1:1:1 at 130 degrees C produced a yellowish transparent polymeric gel without any precipitation, which after pyrolysis at 350-400 degrees C was converted to a powder precursor for KTiNbO5. The complete formation of KTiNbO5 occurred when the powder precursor was heat-treated at 700 degrees C for 2 h in static air. KTiNbO5 via the PC route, combined with NiO, showed more than ten times larger photocatalytic activities for the decomposition of water compared with those for a sample prepared at 1100 degrees C by the conventional solid-state reaction method. The difference in the photocatalytic activities between the two samples was basically understood in terms of the difference in the surface areas. A partial loss of potassium was likely in the host KTiNbO5 material prepared by the high-temperature solid-state reaction method, which was supposed to be a factor altering the surface structure, thus influencing the overall photocatalytic activity of potassium titanoniobates. (C) 1999 Elsevier Science S.A. All rights reserved.
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Mechano-catalytic overall water splitting Reviewed
S Ikeda, T Takata, T Kondo, G Hitoki, M Hara, JN Kondo, K Domen, H Hosono, H Kawazoe, A Tanaka
CHEMICAL COMMUNICATIONS pp.2185-2186 ( 20 ) 2185 - 2186 1998.10
Joint Work
Authorship：Lead author Publisher：ROYAL SOC CHEMISTRY
Mechano-catalysis, a novel and simple method to decompose water into H-2 and O-2 in which mechanical energy is directly converted into chemical energy, is demonstrated.
DOI： 10.1039/a804549f
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Preparation of a high active photocatalyst, K2La2Ti3O10, by polymerized complex method and its photocatalytic activity of water splitting Reviewed
S Ikeda, M Hara, JN Kondo, K Domen, H Takahashi, T Okubo, M Kakihana
JOURNAL OF MATERIALS RESEARCH 13 ( 4 ) 852 - 855 1998.4
Joint Work
Authorship：Lead author Publisher：MATERIALS RESEARCH SOCIETY
A layered perovskite type oxide, K2La2Ti3O10, was prepared by a gel technique using the polymerized complex (PC) method. A single phase K3La2Ti3O10 was Obtained by adding twice the potassium required for stoichiometry. The Ni-K2La2Ti3O10 catalyst prepared by the PC method exhibited a higher photocatalytic activity for decomposition of H2O into H-2 and O-2 than that prepared by a conventional solid state reaction.
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Cu2O as a photocatalyst for overall water splitting under visible light irradiation Reviewed
Hara, M; Kondo, T; Komoda, M; Ikeda, S; Shinohara, K; Tanaka, A; Kondo, JN; Domen, K
CHEMICAL COMMUNICATIONS ( 3 ) 357 - 358 1998.2
Joint Work
DOI： 10.1039/a707440i
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Preparation of K2La2Ti3O10 by polymerized complex method and photocatalytic decomposition of water Reviewed
S Ikeda, M Hara, JN Kondo, K Domen, H Takahashi, T Okubo, M Kakihana
CHEMISTRY OF MATERIALS 10 ( 1 ) 72 - 77 1998.1
Joint Work
Authorship：Lead author Publisher：AMER CHEMICAL SOC
A polymerized complex (PC) technique was applied to the preparation of a highly active photocatalyst, K2La2Ti3O10, with a layered perovskite type structure to decompose H2O into H-2 and O-2. The catalyst prepared by the PC technique had a higher photocatalytic activity than that prepared by conventional solid-state reaction method.
DOI： 10.1021/cm970221c
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Effect of the particle size for photocatalytic decomposition of water on Ni-loaded K4Nb6O17 Reviewed
S Ikeda, A Tanaka, K Shinohara, M Hara, JN Kondo, KI Maruya, K Domen
MICROPOROUS MATERIALS 9 ( 43226 ) 253 - 258 1997.5
Joint Work
Authorship：Lead author Publisher：ELSEVIER SCIENCE BV
The photocatalytic activities of water splitting by small particles (0.1-2 mu m) of K4Nb6O17 were studied. The milled catalysts were prepared by two kinds of ball-milling methods from the powder whose particles were several tens of micrometers in diameter. The surface area of the milled catalyst measured by N-2 adsorption at 77 K increased by an order of magnitude. The crystal structure was almost retained as K4Nb6O17, as evidenced by the results of X-ray diffraction and scanning electron micrography. The photocatalytic activity for an overall decomposition of water of the Ni-loaded K4Nb6O17 was twice as high as that for the original catalyst. (C) 1997 Elsevier Science B.V.