Associate Professor


2-4 Hibikino, Wakamatsu-ku, Kitakyushu-shi, Fukuoka

Research Fields, Keywords

Spectroscopy, Photocatalyst, Photovoltaic Cell


E-mail address

Undergraduate Education 【 display / non-display

  • 2002.03   Osaka University   Faculty of Engineering Science   Advanced a Year   JAPAN

Post Graduate Education 【 display / non-display

  • 2007.03  Hokkaido University  Graduate School, Division of Earth Environmental Science and Technology  Environmental Materials Science  Doctoral Program  Completed  JAPAN

  • 2004.03  Osaka University  Graduate School, Division of Engineering Science  Master's Course  Completed  JAPAN

Degree 【 display / non-display

  • Hokkaido University -  Doctor of Environmental Earth Science  2007.03

Biography in Kyutech 【 display / non-display

  • 2012.11

    Kyushu Institute of TechnologyFaculty of Engineering   Department of Materials Science   Associate Professor  


Publications (Article) 【 display / non-display

  • Photoacoustic Fourier Transform Near- and Mid-Infrared Spectroscopy for Measurement of Energy Levels of Electron Trapping Sites in Titanium(IV) Oxide Photocatalyst Powders

      123 ( 19 ) 12169 - 12175   2019.05  [Refereed]

     View Summary

    © 2019 American Chemical Society. Electron trapping sites in titanium(IV) oxide photocatalyst powders were investigated by photoacoustic (PA) Fourier transform near-infrared spectroscopy (FT-NIR) and mid-infrared spectroscopy (FT-MIR). PA measurements using FT-NIR and FT-MIR enabled in situ observation of the energy levels of electron trapping sites in wide energy levels (0.1-1.9 eV) below the bottom of the conduction band. During ultraviolet (UV) irradiation, PA intensity increased depending on the wavenumber, and changes in the PA spectra were observed as a result of the trivalent titanium species generated by accumulation of electrons at trapping sites. Moreover, the PA spectral shape during UV irradiation was essentially different between the crystal structures, and it greatly depended on the crystal structure rather than other properties such as specific surface area and particle size. The results for various samples suggest that anatase has shallower energy levels of electron trapping sites than those of rutile and brookite, with the main energy level of the trapping sites being deep in the order of brookite > rutile > anatase. Thus, the PA technique using FT-NIR and FT-MIR is an effective method for measurements of energy levels of electron trapping sites in semiconductor photocatalysts.

    DOI Scopus

  • Contribution of Discharge Excited Atomic N, N2*, and N2+ to a Plasma/Liquid Interfacial Reaction as Suggested by Quantitative Analysis

      20   1467 - 1474   2019.01  [Refereed]

     View Summary

    © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Electric-discharge nitrogen comprises three main types of excited nitrogen species-atomic nitrogen (N atom ), excited nitrogen molecules (N 2 *), and nitrogen ions (N 2+ ) – which have different lifetimes and reactivities. In particular, the interfacial reaction locus between the discharged nitrogen and the water phase produces nitrogen compounds such as ammonia and nitrate ions (denoted as N-compounds generically); this is referred to as the plasma/liquid interfacial (P/L) reaction. The N atom amount was analyzed quantitatively to clarify the contribution of N atom to the P/L reaction. We focused on the quantitative relationship between N atom and the produced N-compounds, and found that both N 2 * and N 2+ , which are active species other than N atom , contributed to P/L reaction. The production of N-compounds from N 2 * and N 2+ was enhanced upon UV irradiation of the water phase, but the production of N-compounds from N atom did not increase by UV irradiation. These results revealed that the P/L reactions starting from N atom and those starting from N 2* and N 2+ follow different mechanisms.

    DOI Scopus

  • Operando Analysis of Electron Accumulation in Titanium(IV) Oxide Particles in an Aqueous Suspension Using a Photoacoustic Spectroscopic Method

      123 ( 1 ) 222 - 226   2018.12  [Refereed]

     View Summary

    Copyright © 2018 American Chemical Society. The time course of photoabsorption of an aqueous suspension of titanium(IV) oxide (TiO2) particles was studied using photoacoustic (PA) spectroscopy. In the absence of an electron acceptor and the presence of an electron donor, ultraviolet irradiation increased PA intensity because photoabsorption of the suspension increased due to trivalent titanium (Ti3+) species generated by electron accumulation in TiO2 particles. In contrast, the addition of methylene blue (MB) as an acceptor caused a decrease in PA intensity, indicating that accumulated electrons were consumed by reduction of MB to colorless leuco-MB. The results for various TiO2 particles indicated that Ti3+ density is determined by this method. Moreover, the measurement can be applicable to quantitative operando analysis for accumulated electrons in a photocatalytic reaction. ©

    DOI Scopus

  • Mid-infrared absorption of trapped electrons in titanium(IV) oxide particles using a photoacoustic FTIR technique

      20 ( 38 ) 24519 - 24522   2018.09  [Refereed]

     View Summary

    © 2018 the Owner Societies. Mid-infrared absorption of titanium(iv) oxide (TiO2) under ultraviolet (UV) irradiation was studied by Fourier transform infrared spectroscopy using a photoacoustic (PA) technique. UV irradiation induced an upward shift of the PA spectra, which is due to the trivalent titanium (Ti3+) species produced by electron accumulation. The PA spectra under UV irradiation mainly depend on the crystal structure, indicating that the energy levels of Ti3+are largely determined by crystal structures.

    DOI Scopus

  • Reversed double-beam photoacoustic spectroscopy of metal-oxide powders for estimation of their energy-resolved distribution of electron traps and electronic-band structure

      264   83 - 90   2018.02  [Refereed]

     View Summary

    © 2018 Elsevier Ltd A novel instrumental methodology, reversed double-beam photoacoustic spectroscopy (RDB-PAS), was developed for measuring the energy-resolved distribution of electron traps (ERDT) of metal-oxide powders. In the RDB-PAS measurement, electrons in the valence band of a powder sample are directly excited to electron traps (ETs) and accumulated in the ETs from the deeper (anodic) side to the shallower (cathodic) side by wavelength-scanned continuous light, and the increase in photoabsorption of electron-filled ETs is measured by modulated light at a fixed wavelength by PAS. It was shown that ERDT/CBB (conduction-band bottom) patterns measured by RDB-PAS can be used for not only identification and detailed characterization of a wide range of metal-oxide powder samples but also estimation of difference in apparent valence-band top (VBT) position.

    DOI Scopus

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Publications (Books) 【 display / non-display

  • ルチルTiO2単結晶

    村上直也,横野照尚 ( Joint Work )

    触媒調製ハンドブック  2011.04 ISBN: 978-4-8604-3377-2

Conference Prsentations (Oral, Poster) 【 display / non-display

  • ボールミル処理した酸化チタン(IV)光触媒粉末における欠陥生成の光音響分光解析


    日本化学会第100春季年会(2020)  2020.03  -  2020.03 

  • 酸化チタン(IV)中に電気化学的に蓄積された電子の光音響解析


    日本化学会第100春季年会(2020)  2020.03  -  2020.03 

  • Photoacoustic Measurement of Intrinsic Quantum Efficiency for Photoanodic Reaction at n-Type Semiconductor Film Deposited on Transparent Conductive Substrate

    Naoya Murakami,Keita Okuzono

    The 3rd International Solar Fuels Conference (ISF-3) / International Conference on Artificial Photosynthesis-2019 (ICARP2019)  2019.11  -  2019.11 

  • Photoacoustic Spectroscopic Analysis of In-Gap States of Rhodium-Doped Strontium Titanate Treated by Ball Milling

    Tatsuki Shinoda, Naoya Murakami, Kenta Watanabe, Akihiko Kudo

    The 3rd International Solar Fuels Conference (ISF-3) / International Conference on Artificial Photosynthesis-2019 (ICARP2019)  2019.11  -  2019.11 

  • 半導体光電極の最適化方法の確立


    第124回触媒討論会  2019.09  -  2019.09 

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Lectures 【 display / non-display

  • 大気活性成分の定量

    エコテクノ2017、第12回先端エコフィッティング技術研究開発センターワークショップ   2017.11.20 

  • 光音響分光法による半導体ナノ粒子の光触媒特性の評価

    第21回規則性多孔体研究会セミナー   2016.12.01 

Honors and Awards 【 display / non-display

  • Honda-Fujishima Prize

    2011.03.30     JAPAN

  • The 18th International Conference on Photochemical Conversion and Storage of Solar Energy, Best Poster Award

    2010.07.30     JAPAN

    Winner: Naoya Murakami,Teruhisa Ohno