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Akihiko Kudo

Bio: Akihiko Kudo is an academic researcher from Tokyo University of Science. The author has contributed to research in topics: Water splitting & Photocatalysis. The author has an hindex of 21, co-authored 31 publications receiving 3523 citations. Previous affiliations of Akihiko Kudo include University of Tokyo & Tokyo Institute of Technology.

Papers
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Journal ArticleDOI
TL;DR: In this article, a 2.3 eV band gap was used for O2 evolution from aqueous solutions containing Ag+ as an electron scavenger under visible light irradiation (λ > 520 nm), and the quantum yield was 0.5% at 450 nm.
Abstract: BiVO4 with a 2.3 eV band gap showed an activity for O2 evolution from aqueous solutions containing Ag+ as an electron scavenger under visible light irradiation (λ > 520 nm). The quantum yield was 0.5% at 450 nm.

639 citations

Journal ArticleDOI
TL;DR: In this article, the authors used NiO as a cocatalyst for water splitting into H2 and O2 in pure water without any additives under UV irradiation, and found that NiO increased the photocatalytic activity of the NiO(0.15 wt %)/Sr2Ta2O7 photocatalyst.
Abstract: Sr2Ta2O7 and Sr2Nb2O7 with similar layered perovskite structure showed activities for water splitting into H2 and O2 in pure water without any additives under UV irradiation. The band gaps of Sr2Ta2O7 and Sr2Nb2O7 were 4.6 and 3.9 eV, respectively. Sr2Ta2O7 gave H2 and O2 from pure water under UV irradiation even in the absence of a cocatalyst. The activity of Sr2Ta2O7 was much increased by loading NiO as a cocatalyst even without pretreatment. The quantum yield of the NiO(0.15 wt %)/Sr2Ta2O7 photocatalyst was 12% at 270 nm. On the other hand, native Sr2Nb2O7 did not possess the activity. The high activity was obtained for the Sr2Nb2O7 photocatalyst when NiO was loaded and pretreated. Factors affecting the photocatalytic activities were discussed by using the Sr2Ta2O7 and Sr2Nb2O7 powder with similar layered perovskite structure. A predominant factor affecting the photocatalytic behavior of Sr2Ta2O7 and Sr2Nb2O7 is the conduction band levels formed by Ta5d and Nb4d.

583 citations

Journal ArticleDOI
TL;DR: The water splitting proceeded with the application of an external bias smaller than 1.23 V versus a Pt counter electrode under visible-light irradiation and also using a solar simulator, suggesting that solar energy conversion should be possible with the present photoelectrochemical water splitting.
Abstract: A Rh-doped SrTiO3 (SrTiO3:Rh) photocatalyst electrode that was readily prepared by pasting SrTiO3:Rh powder onto a transparent indium tin oxide electrode gave a cathodic photocurrent under visible-light irradiation (λ > 420 nm), indicating that the SrTiO3:Rh photocatalyst electrode possessed p-type semiconductor character. The cathodic photocurrent increased with an increase in the amount of doped Rh up to 7 atom %. The incident-photon-to-current efficiency at 420 nm was 0.18% under an applied potential of −0.7 V vs Ag/AgCl for the SrTiO3:Rh(7 atom %) photocatalyst electrode. The photocurrent was confirmed to be due to water splitting by analyzing the evolved H2 and O2. The water splitting proceeded with the application of an external bias smaller than 1.23 V versus a Pt counter electrode under visible-light irradiation and also using a solar simulator, suggesting that solar energy conversion should be possible with the present photoelectrochemical water splitting.

385 citations

Journal ArticleDOI
TL;DR: In this article, the photocatalytic properties of various tantalates were investigated for the decomposition of distilled water into H2 and O2 without co-catalysts.

367 citations


Cited by
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Journal ArticleDOI
TL;DR: It is shown that an abundant material, polymeric carbon nitride, can produce hydrogen from water under visible-light irradiation in the presence of a sacrificial donor.
Abstract: The production of hydrogen from water using a catalyst and solar energy is an ideal future energy source, independent of fossil reserves. For an economical use of water and solar energy, catalysts that are sufficiently efficient, stable, inexpensive and capable of harvesting light are required. Here, we show that an abundant material, polymeric carbon nitride, can produce hydrogen from water under visible-light irradiation in the presence of a sacrificial donor. Contrary to other conducting polymer semiconductors, carbon nitride is chemically and thermally stable and does not rely on complicated device manufacturing. The results represent an important first step towards photosynthesis in general where artificial conjugated polymer semiconductors can be used as energy transducers.

9,751 citations

Journal ArticleDOI
TL;DR: 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.
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)

8,850 citations

Journal ArticleDOI
TL;DR: Approaches to Modifying the Electronic Band Structure for Visible-Light Harvesting and its Applications d0 Metal Oxide Photocatalysts 6518 4.4.1.
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

6,332 citations

Journal ArticleDOI
27 Feb 2015-Science
TL;DR: The design and fabrication of a metal-free carbon nanodot–carbon nitride (C3N4) nanocomposite is reported and its impressive performance for photocatalytic solar water splitting is demonstrated.
Abstract: The use of solar energy to produce molecular hydrogen and oxygen (H2 and O2) from overall water splitting is a promising means of renewable energy storage. In the past 40 years, various inorganic and organic systems have been developed as photocatalysts for water splitting driven by visible light. These photocatalysts, however, still suffer from low quantum efficiency and/or poor stability. We report the design and fabrication of a metal-free carbon nanodot-carbon nitride (C3N4) nanocomposite and demonstrate its impressive performance for photocatalytic solar water splitting. We measured quantum efficiencies of 16% for wavelength λ = 420 ± 20 nanometers, 6.29% for λ = 580 ± 15 nanometers, and 4.42% for λ = 600 ± 10 nanometers, and determined an overall solar energy conversion efficiency of 2.0%. The catalyst comprises low-cost, Earth-abundant, environmentally friendly materials and shows excellent stability.

3,553 citations

Journal ArticleDOI
TL;DR: This article reviews state-of-the-art research activities in the field, focusing on the scientific and technological possibilities offered by photocatalytic materials, and highlights crucial issues that should be addressed in future research activities.
Abstract: Semiconductor photocatalysis has received much attention as a potential solution to the worldwide energy shortage and for counteracting environmental degradation. This article reviews state-of-the-art research activities in the field, focusing on the scientific and technological possibilities offered by photocatalytic materials. We begin with a survey of efforts to explore suitable materials and to optimize their energy band configurations for specific applications. We then examine the design and fabrication of advanced photocatalytic materials in the framework of nanotechnology. Many of the most recent advances in photocatalysis have been realized by selective control of the morphology of nanomaterials or by utilizing the collective properties of nano-assembly systems. Finally, we discuss the current theoretical understanding of key aspects of photocatalytic materials. This review also highlights crucial issues that should be addressed in future research activities.

3,265 citations