Author
Kei Murakoshi
Other affiliations: Shinshu University, National Presto Industries, Nippon Telegraph and Telephone ...read more
Bio: Kei Murakoshi is an academic researcher from Hokkaido University. The author has contributed to research in topics: Plasmon & Localized surface plasmon. The author has an hindex of 45, co-authored 245 publications receiving 7993 citations. Previous affiliations of Kei Murakoshi include Shinshu University & National Presto Industries.
Papers published on a yearly basis
Papers
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Donostia International Physics Center1, Rovira i Virgili University2, MacDiarmid Institute for Advanced Materials and Nanotechnology3, Victoria University of Wellington4, University of Cambridge5, University of California, Santa Barbara6, Queen's University Belfast7, Technical University of Denmark8, University of Victoria9, Chung-Ang University10, Leibniz Institute of Photonic Technology11, University of Jena12, Rutgers University13, University of Strathclyde14, University of Liverpool15, University of Iowa16, University of Minnesota17, Heidelberg University18, National Institute of Advanced Industrial Science and Technology19, Chalmers University of Technology20, Humboldt University of Berlin21, University of Michigan22, Jiangnan University23, Stanford University24, Xiamen University25, Ludwig Maximilian University of Munich26, Hokkaido University27, Seoul National University28, University of Illinois at Urbana–Champaign29, Kwansei Gakuin University30, University of Vigo31, Free University of Berlin32, Northwestern University33, University of Duisburg-Essen34, National Research Council35, Indian Institute of Science Education and Research, Thiruvananthapuram36, Duke University37, Northeastern University (China)38, Temple University39, Wuhan University40, Japan Advanced Institute of Science and Technology41, Jilin University42, Ikerbasque43
TL;DR: Prominent authors from all over the world joined efforts to summarize the current state-of-the-art in understanding and using SERS, as well as to propose what can be expected in the near future, in terms of research, applications, and technological development.
Abstract: The discovery of the enhancement of Raman scattering by molecules adsorbed on nanostructured metal surfaces is a landmark in the history of spectroscopic and analytical techniques. Significant experimental and theoretical effort has been directed toward understanding the surface-enhanced Raman scattering (SERS) effect and demonstrating its potential in various types of ultrasensitive sensing applications in a wide variety of fields. In the 45 years since its discovery, SERS has blossomed into a rich area of research and technology, but additional efforts are still needed before it can be routinely used analytically and in commercial products. In this Review, prominent authors from around the world joined together to summarize the state of the art in understanding and using SERS and to predict what can be expected in the near future in terms of research, applications, and technological development. This Review is dedicated to SERS pioneer and our coauthor, the late Prof. Richard Van Duyne, whom we lost during the preparation of this article.
1,768 citations
TL;DR: In this article, the plasmonic photoelectric conversion from visible to near-infrared wavelength without deteriorating photo-electric conversion by using electrodes in which gold nanorods are elaborately arrayed on the surface of a TiO2 single crystal.
Abstract: Nanoparticles of noble metals exhibit localized surface plasmons (LSPs) associated with the enhancement of an electromagnetic field due to its localization in nanometric domains at the surface of nanoparticles. We demonstrate the plasmonic photoelectric conversion from visible to near-infrared wavelength without deteriorating photoelectric conversion by using electrodes in which gold nanorods are elaborately arrayed on the surface of a TiO2 single crystal.
407 citations
TL;DR: In this article, a quasi-solid-state dye-sensitized solar cells were fabricated using low-molecular-weight gelators and the formation of polyiodide ions, such as I3- and I5-, caused by addition of iodine was confirmed by Raman spectroscopic measurement.
Abstract: Quasi-solid-state dye-sensitized solar cells were fabricated using low-molecular-weight gelators. They showed comparable photoenergy conversion efficiencies to the liquid cell at high illumination intensity up to AM 1.5 (1 sun). Conductivity measurements of the electrolyte phases revealed that the gelation does not affect the conductivity of the electrolyte and that the conductivity increased with an increase of iodine in both gel electrolytes and liquid electrolyte. The formation of polyiodide ions, such as I3- and I5-, caused by addition of iodine was confirmed by Raman spectroscopic measurement. The self-diffusion of iodide species in the gel electrolyte was found about a quarter of that of I- in acetonitrile. The formation of less-mobile polyiodide ions in electrolyte increased the conductivity in the mesoporous phase, which should be rationalized as due to the Grotthuss-type electron exchange mechanism caused by rather packed polyiodide species in the electrolytes. The optimized quasi-solid-state cel...
359 citations
TL;DR: In this paper, a dye-sensitized TiO2 solar cell was constructed using a ruthenium complex, cis-di(thiocyanato)-N,N′-bis(2,2′-bipyridyl-4,4′-dicar☐ylic acid)-ruthenIUM (II), as a photosensitizing molecule (dye) on TiO 2 nanocrystallite films to determine the interfacial binding effect on photoenergy conversion efficiency.
295 citations
TL;DR: Investigations of surface intermediates of photocatalytic reactions on nanocrystalline TiO(2) films in contact with aqueous solutions revealed the formation of the surface peroxo species, giving the 943 cm(-)(1) band, probably with the surface superoxo Species, TiOO.
Abstract: Multiple internal reflection infrared spectroscopy was applied to in situ investigations of surface intermediates of photocatalytic reactions on nanocrystalline TiO2 films in contact with aqueous solutions. UV irradiation in the presence of dissolved O2 caused the appearance of new bands peaked at 943, 838, and 1250−1120 cm-1 together with intensity changes in other bands. Investigations of influences of the solution pH, the presence or absence of hole and electron scavengers, and isotopic H2O → D2O exchange on the spectral changes have revealed that the primary step of photocatalytic O2 reduction is the formation of the surface peroxo species, Ti(O2), giving the 943 cm-1 band, probably with the surface superoxo species, TiOO·, as a precursor, in neutral and acidic solutions. The surface peroxo species is then transformed to the surface hydroperoxo, TiOOH, giving the 838 and 1250−1120 cm-1 bands, by protonation in the dark. This is, to our knowledge, the first direct in situ spectroscopic detection of pri...
275 citations
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TL;DR: Dye-sensitized solar cells (DSCs) offer the possibilities to design solar cells with a large flexibility in shape, color, and transparency as mentioned in this paper, and many DSC research groups have been established around the world.
Abstract: Dye-sensitized solar cells (DSCs) offer the possibilities to design solar cells with a large flexibility in shape, color, and transparency. DSC research groups have been established around the worl ...
8,707 citations
TL;DR: The field of photocatalysis can be traced back more than 80 years to early observations of the chalking of titania-based paints and to studies of the darkening of metal oxides in contact with organic compounds in sunlight as discussed by the authors.
5,729 citations
TL;DR: In this article, the up-to-date development of the above-mentioned technologies applied to TiO 2 photocatalytic hydrogen production is reviewed, based on the studies reported in the literature, metal ion-implantation and dye sensitization are very effective methods to extend the activating spectrum to the visible range.
Abstract: Nano-sized TiO 2 photocatalytic water-splitting technology has great potential for low-cost, environmentally friendly solar-hydrogen production to support the future hydrogen economy. Presently, the solar-to-hydrogen energy conversion efficiency is too low for the technology to be economically sound. The main barriers are the rapid recombination of photo-generated electron/hole pairs as well as backward reaction and the poor activation of TiO 2 by visible light. In response to these deficiencies, many investigators have been conducting research with an emphasis on effective remediation methods. Some investigators studied the effects of addition of sacrificial reagents and carbonate salts to prohibit rapid recombination of electron/hole pairs and backward reactions. Other research focused on the enhancement of photocatalysis by modification of TiO 2 by means of metal loading, metal ion doping, dye sensitization, composite semiconductor, anion doping and metal ion-implantation. This paper aims to review the up-to-date development of the above-mentioned technologies applied to TiO 2 photocatalytic hydrogen production. Based on the studies reported in the literature, metal ion-implantation and dye sensitization are very effective methods to extend the activating spectrum to the visible range. Therefore, they play an important role in the development of efficient photocatalytic hydrogen production.
3,714 citations
TL;DR: A dye-sensitized heterojunction of TiO2 with the amorphous organic hole-transport material 2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenyl-amine)9,9′-spirobifluorene (OMeTAD) was described in this article.
Abstract: Solar cells based on dye-sensitized mesoporous films of TiO2 arelow-cost alternatives to conventional solid-state devices1. Impressive solar-to-electrical energy conversion efficiencies have been achieved with such films when used in conjunction with liquid electrolytes2. Practical advantages may be gained by the replacement of the liquid electrolyte with a solid charge-transport material. Inorganic p-type semiconductors3,4 and organic materials5,6,7,8,9 have been tested in this regard, but in all cases the incident monochromatic photon-to-electron conversion efficiency remained low. Here we describe a dye-sensitized heterojunction of TiO2 with the amorphous organic hole-transport material 2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenyl-amine)9,9′-spirobifluorene (OMeTAD; refs. 10 and 11). Photoinduced charge-carrier generation at the heterojunction is very efficient. A solar cell based on OMeTAD converts photons to electric current with a high yield of 33%.
3,386 citations
TL;DR: In this article, the absolute energy positions of conduction and valence band edges were compiled for about 50 each semiconducting metal oxide and metal sulfide minerals, and the relationship between energy levels at mineral semiconductor-electrolyte interfaces and the activities of these minerals as a catalyst or photocatalyst in aqueous redox reactions were reviewed.
Abstract: The absolute energy positions of conduction and valence band edges were compiled for about 50 each semiconducting metal oxide and metal sulfide minerals. The relationships between energy levels at mineral semiconductor-electrolyte interfaces and the activities of these minerals as a catalyst or photocatalyst in aqueous redox reactions are reviewed. The compilation of band edge energies is based on experimental flatband potential data and complementary empirical calculations from electronegativities of constituent elements. Whereas most metal oxide semiconductors have valence band edges 1 to 3 eV below the H2O oxidation potential (relative to absolute vacuum scale), energies for conduction band edges are close to, or lower than, the H2O reduction potential. These oxide minerals are strong photo-oxidation catalysts in aqueous solutions, but are limited in their reducing power. Non-transition metal sulfides generally have higher conduction and valence band edge energies than metal oxides; therefore, valence band holes in non-transition metal sulfides are less oxidizing, but conduction band electrons are exceedingly reducing. Most transition-metal sulfides, however, are characterized by small band gaps (<1 eV) and band edges situated within or close to the H2O stability potentials. Hence, both the oxidizing power of the valence band holes and the reducing power of the conduction band electrons are lower than those of non-transition metal sulfides.
3,145 citations