Akihiko KudoDepartment of Applied Chemistry, Faculty of Science, Tokyo University of Science E-mail: a-kudo@rs.kagu.tus.ac.jp |
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Title
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Photocatalytic and photoelectrochemical hydrogen production from water |
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Abstract |
The importance of hydrogen energy has recently been re-recognized because of the interest in clean energy. Hydrogen is mainly produced by steam reforming of hydrocarbons such as methane in industry. Hydrogen must be produced from water using a renewable energy source, if one considers the energy and environmental issues. Therefore, photocatalytic water splitting is still a challenging reaction because it is an ultimate solution to these serious problems, even if this research history is long. In the present paper, we introduce various metal oxide and sulfide photocatalysts aiming at water splitting [1]. Many visible-light-driven photocatalysts have also been developed through band engineering by doping of metal cations, new valence formation, and by making solid solution. Among them, Ru/SrTiO3 doped with Rh showed high activity for H2 evolution from aqueous solutions containing a reducing reagent under visible light irradiation (wavelength > 420 nm). BiVO4 showed high activity for O2 evolution in the presence of sacrificial reagent (Ag+). Overall water splitting under visible light irradiation has been achieved by construction of a Z-scheme photocatalysis system employing these visible-light-driven photocatalysts (Ru/SrTiO3:Rh and BiVO4) and an Fe3+/ Fe2+ redox couple as an electron mediator. Moreover, Z-scheme photocatalysis system consisting of Ru/SrTiO3:Rh and BiVO4 without the electron mediator showed activity for water splitting when pH was adjusted at 3.5. In this system, inter-particle electron transfer proceeded resulting in constructing the Z-scheme. These Z-scheme systems with and without an electron mediator were active for solar water splitting. Rh-doped SrTiO3 (SrTiO3:Rh) photocatalyst electrode which was readily prepared by pasting SrTiO3:Rh powder on an indium tin oxide (ITO) transparent electrode gave cathodic photocurrent under visible light irradiation (¥ë>420 nm) indicating the SrTiO3:Rh photocatalyst electrode possessed p-type semiconductor character [2]. The incident photon to current efficiency (IPCE) at 420 nm was 0.18% under applying a 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 evolved H2 and O2. The water splitting proceeded with applying an external bias smaller than 1.23 V vs. a counter Pt electrode under visible light irradiation and also using a solar simulator, suggesting solar energy conversion should be possible with the present photoelectrochemical water splitting. A wet photovoltaic cell consisting of the BiVO4 photoelectrode and a Pt counter electrode was also constructed for water splitting. H2 and O2 evolved from water at less than 1.23V of an external applied bias to the Pt counter electrode under visible light and simulated sunlight irradiation [3]. [1] A. Kudo and Y. Miseki, Chem. Soc. Rev., 2009, 38, 253. [2] K. Iwashina and A. Kudo, J. Am. Chem. Soc. 2011, 133, 13272. [3] A. Iwase and A. Kudo, J. Mater. Chem., 2010, 20, 7536. |
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Can LiState Key Laboratory of Catalysis Dalian National Laboratory for Clean Energy Dalian Institute of Chemical Physics E-mail: canli@dicp.ac.cn
Homepage: http://www.canli.dicp.ac.cn |
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Title
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Photocatalytic Hydrogen Production Utilizing Solar Energy
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Abstract |
Solar energy is the primary source for clean and renewable energy alternative. The concerns about the depletion of fossil fuel reserves and the pollution caused by continuously increasing energy demands make solar fuels an attractive energy source. This lecture discusses the key issues concerning the photocatalytic materials designating and preparation for the productions of solar fuels, mainly photocatalytic hydrogen production utilizing solar energy, focusing on the fundamental understanding of photocatalysis and photochemical reactions on semiconductor-based photocatalysts. Semiconductor-based nano materials are believed to be the most promising components for photocatalysts, so the discovery and preparation of novel semiconductor materials are crucial for the development of advanced photocatalysts. To convert solar energy efficiently to chemical energy, much attention has been paid to reducing charge recombination and improving solar energy conversion efficiency. Our recent results demonstrate that the formation of surface phase junction and hetero-junction on semiconductor catalysts can significantly enhance the activity in photocatalytic hydrogen production. By mimicking the photosynthesis, loading spatially separated dual cocatalysts for oxidation and reduction on semiconductor nanoparticles can effectively avoid the charge recombination and consequently increase the photocatalytic activity. A recent progress made in photocatalytic hydrogen production shows that a quantum yield up to 93% can be achieved for Pt-PdS/CdS catalysts where the dual co-catalysts, Pt and PdS nanoparticles act as reduction and oxidation co-catalysts respectively. The finely designing and preparation of junctions at atomic and nano-scale together with right co-catalysts are the promising strategy to develop highly active photocatalysts for solar fuel production. Keywords: Semiconductor; co-catalysts; nano junctions; quantum efficiency; photocatalysis, hydrogen, CO2 reduction, solar fuels, solar energy.
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Shinji Kubo |
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Affiliation& |
Japan Atomic Energy Agency E-mail: kubo.shinji@jaea.go.jp
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Title
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Overview and challenges for hydrogen production using thermochemical
water-splitting cycles
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Abstract |
Hydrogen is an important industrial chemical as well as a potential fuel. To
obtain hydrogen from water, a hydrogen production technology and a primary
energy source are required, such as fossil fuel, natural energy, and nuclear
power. The potential advantages of hydrogen produced from the water used in the
thermochemical cycles are that it offers an economical hydrogen supply in very
large volumes, superior energy security, and environmentally friendly operation.
Attention has come to be paid to the studies for the cycles in the last decade.
This lecture presents a principle of thermochemical cycle, outlines of the
chemical processes and nuclear hydrogen production systems, and recent
progresses of its R&Ds.
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Plenary Speaker
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Ibrahim DincerProfessor of Mechanical Engineering |
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Affiliation& |
Faculty of Engineering and Applied Tel: 905-721-8668 ext: 5723 E-mail: Ibrahim.Dincer@uoit.ca
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Title
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Innovative Energy Solutions with Integrated Hydrogen Production Systems
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Abstract |
The hydrogen economy was conceptually shaped
out in late 1960s and first half of 1970s as a natural reaction of prominent scientists,
researchers and engineers to the dependence of world energy use on fossil
fuels. The International Association of Hydrogen Energy (IAHE) was initiated by
1974 with the aim to develop and implement a hydrogen economy for future
generations. Since then IAHE has been promoting the idea of hydrogen economy at
all societal levels starting from general public to the governments. Such
comprehensive efforts have made it possible for countries to recognize the role
of hydrogen energy for a more sustainable future. At present water electrolysis
and steam methane reforming are recognized as two most common methods for
hydrogen production. Due to their environmental consequences there is still a
strong need for sustainable hydrogen production systems. In this presentation,
the main focus will be on coupling hydrogen production options with renewable
energy systems in an integrated fashion for multigeneration purposes (including
power, heat, hot water, cooling and fresh water) for better efficiency, cost
effectiveness and environment. The integrated systems studied are based on
solar, wind, geothermal, hydro and biomass using either heat or work or heat
and work in a hybridized manner. These systems will also be assessed through
energy and exergy efficiencies and compared for practical applications. Furthermore,
the results of some recent life cycle assessment studies for hydrogen
production methods will be discussed to give a broad picture for practical
applications.
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Biographical Sketch |
Ibrahim Dincer is a full professor of Mechanical Engineering in the
Faculty of Engineering and Applied Science at UOIT. He is Vice President for Strategy in International Association for
Hydrogen Energy (IAHE) and Vice-President for World Society of Sustainable
Energy Technologies (WSSET). Renowned for his pioneering works in the area of
sustainable energy technologies he has authored and co-authored numerous books
and book chapters, more than 750 refereed journal and conference papers, and many
technical reports. He has chaired many national and international conferences,
symposia, workshops and technical meetings. He has delivered more than 200
keynote and invited lectures. He is an active member of various international
scientific organizations and societies, and serves as editor-in-chief (for
International Journal of Energy Research by Wiley, and International Journal of
Exergy and International Journal of Global Warming by Inderscience), associate
editor, regional editor, and editorial board member on various prestigious
international journals. He is a recipient of several research, teaching and
service awards, including the Premier's research excellence award in
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