Publications

42. "Efficient Visible-Light-Driven Water Oxidation by a Carbon Nitride Modified with Cobalt Polyoxometalate Molecular Catalyst"
    Yuki Tomita, Natsuki Taira, Ken Sakai,* Hironobu Ozawa*
    ACS Catal., 2024, 14, 5788-5794.
    


41. "A Highly Efficient and Stable Molecular-Based TiO₂ Photoanode for Photoelectrochemical Water Splitting Achieved by Pyridyl Anchoring Technique"
    Xin Yan, Ken Sakai,* Hironobu Ozawa*
    ACS Catal., 2023, 13, 13456-13465.
    


40. "Efficient syngas production with controllable CO:H₂ ratios based on the aqueous electrocatalytic CO₂ reduction over mesoporous TiO₂ films modified with a cobalt porphyrin molecular catalyst"
    Hironobu Ozawa,* Ryoma Kikunaga, Hajime Suzuki, Ryu Abe, Ken Sakai*
    Sustainable Energy Fuels, 2023, 7, 1627-1632.
    


39. "Two-Electrode Solar Water Splitting Permitting H₂ Separation at a Dark Cathode"
    Hironobu Ozawa,* Ken Sakai*
    AsiaChem Magazine, 2021, 2, 80-87.
    


38. "Improving the Overall Performance of Photochemical H₂ Evolution Catalyzed by the Co-NHC Complex via the Redox Tuning of Electron Relays"
    Koichi Yatsuzuka, Kosei Yamauchi,* Ken Kawano, Hironobu Ozawa,* Ken Sakai*
    Sustainable Energy Fuels, 2021, 5, 740-749.
    


37. "A Molecular-Based Water Electrolyzer Consisting of Two Mesoporous TiO₂ Electrodes Modified with Metalloporphyrin Molecular Catalysts Showing a Quantitative Faradaic Efficiency"
    Katsuhiro Akamine, Kohei Morita, Ken Sakai,* Hironobu Ozawa*
    ACS Appl. Energy Mater., 2020, 3, 4860-4866.
    


36. "A New Class of Molecular-Based Photoelectrochemical Cell for Solar Hydrogen Production Consisting of Two Mesoporous TiO₂ Electrodes"
    Kohei Morita, Ken Sakai,* Hironobu Ozawa*
    ACS Appl. Energy Mater., 2019, 2, 987-992.
    


35. "A Platinum Porphyrin Modified TiO₂ Electrode for Photoelectrochemical Hydrogen Production from Neutral Water Driven by the Conduction Band Edge Potential of TiO₂"
    Kohei Morita, Kohei Takijiri, Ken Sakai,* Hironobu Ozawa*
    Dalton Trans., 2017, 46, 15181-15185.
    


34. "Highly Stable Chemisorption of Dyes with Pyridyl Anchors over TiO₂: Application in Dye-Sensitized Photoelectrochemical Water Reduction in Aqueous Media"
    Kohei Takijiri, Kohei Morita, Takashi Nakazono, Ken Sakai,* Hironobu Ozawa*
    Chem. Commun., 2017, 53, 3042-3045.
    


33. "Synthesis and Characterization of a RuPt-based Photo-Hydrogen-Evolving Molecular Device Tethered to a Single Viologen Acceptor"
    Masayuki Miyaji, Kyoji Kitamoto, Hironobu Ozawa*, Ken Sakai*
    Eur. J. Inorg. Chem., 2017, 1237-1244.
    


32. "Improved photocatalytic Hydrogen Evolution Driven by Chloro(terpyridine)platinum(II) Derivatives Tethered to a Single Pendant Viologen Acceptor"
    Shu Lin, Kyoji Kitamoto, Hironobu Ozawa*, Ken Sakai*
    Dalton Trans., 2016, 45, 10643-10654.
    


31. "Highly Efficient Dye-Sensitized Solar Cell Based on a Ruthenium Sensitizer Bearing a Hexylthiophene Modified Terpyridine Ligand"
    Hironobu Ozawa, Takahito Sugiura, Takahiro Kuroda, Kouya Nozawa, Hironori Arakawa*
    J. Mater. Chem. A, 2016, 4, 1762-1770.
    


30. "Black-Dye-Based Dye-Sensitized Solar Cells using the Electrolyte Solutions Containing a Quaternary Phosphonium Iodide with a Various Alkyl Chain Length"
    Hironobu Ozawa, Ayako Urayama, Hironori Arakawa*
    Electrochim. Acta, 2016, 187, 73-80.
    


29. "Efficient Ruthenium Sensitizer with an Extended π-Conjugated Terpyridine Ligand for Dye-Sensitized Solar Cells"
    Hironobu Ozawa, Kei Fukushima, Ayako Urayama, Hironori Arakawa*
    Inorg. Chem., 2015, 54, 8887-8889.
    


28. "Novel Near-Infrared Carboxylated 1,3-Indandione Sensitizers for Highly Efficient Flexible Dye-Sensitized Solar Cells"
    Naoyuki Shibayama, Yukiko Inoue, Masahiro Abe, Shingo Kajiyama, Hironobu Ozawa, Hidetoshi Miura, Hironori Arakawa*
    Chem. Commun., 2015, 51, 12795-12798.
    


27. "Ruthenium Sensitizers with a Hexylthiophene-Modified Terpyridine Ligand for Dye-Sensitized Solar Cells: Synthesis, Photo- and Electrochemical Properties, and Adsorption Behavior to the TiO₂ Surface"
    Hironobu Ozawa, Yasuyuki Yamamoto, Hiroki Kawaguchi, Ryosuke Shimizu, Hironori Arakawa*
    ACS Appl. Mater. Interfaces, 2015, 7, 3152-3161.
    


26. "Highly Efficient Cosensitized Plastic-Substrate Dye-Sensitized Solar Cells with Black Dye and Pyridine-Anchor Organic Dye"
    Naoyuki Shibayama, Hironobu Ozawa, Yousuke Ooyama, Hironori Arakawa*
    Bull. Chem. Soc. Jpn., 2015, 88, 366-374.
    


25. "Effects of the Alkyl Chain Length of Imidazolium Iodide in the Electrolyte Solution on the Performance of Black-Dye-Based Dye-Sensitized Solar Cells"
    Hironobu Ozawa, Yuki Tawaraya, Hironori Arakawa*
    Electrochim. Acta, 2015, 151, 447-452.
    


24. "Efficient Ruthenium Sensitizer with a Terpyridine Ligand Having a Hexylthiophene Unit for Dye-Sensitized Solar Cells: Effects of the Substituent Position on the Solar Cell Performance"
    Hironobu Ozawa, Takahiro Kuroda, Shohei Harada, Hironori Arakawa*
    Eur. J. Inorg. Chem., 2014, 4734-4739.
    


23. "Novel Ruthenium Sensitizers Having Different Numbers of Carboxyl Groups for Dye-Sensitized Solar Cells: Effects of the Adsorption Manner at the TiO₂ Surface on the Solar Cell Performance"
    Hironobu Ozawa, Takahito Sugiura, Ryosuke Shimizu, Hironori Arakawa*
    Inorg. Chem., 2014, 53, 9375-9384.
    


22. "Ruthenium Sensitizers Having an Ortho-Dicarboxyl Group as an Anchoring Unit for Dye-Sensitized Solar Cells: Synthesis, Photo- and Electrochemical Properties, and Adsorption Behavior to the TiO₂ Surface"
    Hironobu Ozawa, Kei Fukushima, Takahito Sugiura, Ayako Urayama, Hironori Arakawa*
    Dalton Trans., 2014, 43, 13208-13218.
    


21. "A New Cosensitization Method Using the Lewis Acid Sites of a TiO₂ Photoelectrode for Dye-Sensitized Solar Cells"
    Naoyuki Shibayama, Hironobu Ozawa, Masahiro Abe, Yousuke Ooyama, Hironori Arakawa*
    Chem. Commun., 2014, 50, 6398-6401.
    


20. "Dependence of the Efficiency Improvement of Black-Dye-Based Dye-Sensitized Solar Cells on Alkyl Chain Length of Quaternary Ammonium Cations in Electrolyte Solutions"
    Hironobu Ozawa, Yu Okuyama, Hironori Arakawa*
    ChemPhysChem, 2014, 15, 1201-1206.
    


19. "Novel Ruthenium Sensitizers with a Dianionic Tridentate Ligand for Dye-Sensitized Solar Cells: the Relationship Between the Solar Cell Performances and the Electron-Withdrawing Ability of Substituents on the Ligand"
    Hironobu Ozawa, Shunsuke Honda, Daichi Katano, Takahito Sugiura, Hironori Arakawa*
    Dalton Trans., 2014, 43, 8026-8036.
    


18. "Mechanistic Studies of Photoinduced Intramolecular and Intermolecular Electron Transfer Processes in RuPt-Centred Photo-Hydrogen-Evolving Molecular Devices"
    Chettiyam Veettil Suneesh, Bijitha Balan, Hironobu Ozawa, Yuki Nakamura, Tetsuro Katayama, Masayasu Muramatsu,Yutaka Nagasawa, Hiroshi Miyasaka, Ken Sakai*
    Phys. Chem. Chem. Phys., 2014, 16, 1607-1616.
    


17. "Ruthenium Sensitizers with 2,2'-Bipyrimidine or a 5,5'-Disubstituted 2,2'-Bipyrimidine Ligand : Synthesis, Photo- and Electrochemical Properties, and Application to Dye-Sensitized Solar Cells"
    Hironobu Ozawa, Hiroki Kawaguchi, Yu Okuyama, Hironori Arakawa*
    Eur. J. Inorg. Chem., 2013, 5187-5195.
    


16. "Effects of Cation Composition in the Electrolyte on the Efficiency Improvement of Black Dye-Based Dye-Sensitized Solar Cells"
    Hironobu Ozawa, Yu Okuyama, Hironori Arakawa*
    RSC Adv., 2013, 3, 9175-9177.
    


15. "Synthesis and Characterization of a Novel Ruthenium Sensitizer with a Hexylthiophene-Functionalized Terpyridine Ligand for Dye-Sensitized Solar Cells"
    Hironobu Ozawa, Yasuyuki Yamamoto, Kei Fukushima, Satoshi Yamashita, Hironori Arakawa*
    Chem. Lett., 2013, 42, 897-899.
    


14. "Synthesis of a Novel Ruthenium Sensitizer Bearing an Ortho-Dicarboxyphenyl Group as an Anchoring Unit for Dye-Sensitized Solar Cells"
    Hironobu Ozawa, Shohei Oura, Ryosuke Shimizu, Hironori Arakawa*
    Chem. Lett., 2012, 41, 1406-1408.
    


13. "Effective Enhancement of the Performance of Black Dye Based Dye-Sensitized Solar Cells by Metal Oxide Surface Modification of the TiO₂ Photoelectrode"
    Hironobu Ozawa, Yu Okuyama, Hironori Arakawa*
    Dalton Trans., 2012, 41, 5137-5139.
    


12. "Significant Improvement in the Conversion Efficiency of Black-Dye-Based Dye-Sensitized Solar Cells by Cosensitization with Organic Dye"
    Hironobu Ozawa, Ryosuke Shimizu, Hironori Arakawa*
    RSC Adv., 2012, 2, 3198-3200.
    


11. "Characterization of Photovoltaic Performance of the Dye-Sensitized Solar Cell with a Novel Ruthenium Complex Having a Bisdemethoxycurcumin as a Ligand"
    Hironobu Ozawa, Hiroki Kawaguchi, Yu Okuyama, Hironori Arakawa*
    AMBIO, 2012, 41, 149-150.
    


10. "Effects of Dye Adsorption Solvent on the Performances of the Dye-Sensitized Solar Cells Based on Black Dye"
    Hironobu Ozawa, Megumi Awa, Takahiko Ono, Hironori Arakawa*
    Chem. Asian J., 2012, 7, 156-162.
    


9. "Synthesis and Characterization of a Novel Ruthenium Complex Bearing a Curcumin Derivative Ligand and Its Application to Dye-Sensitized Solar Cells"
   Hironobu Ozawa, Hiroki Kawaguchi, Yu Okuyama, Hironori Arakawa*
   Chem. Lett., 2011, 40, 658-660.
   


8. "Photo-Hydrogen-Evolving Molecular Devices Driving Visible-Light-Induced Water Reduction into Molecular Hydrogen: Structure-Activity Relationship and Reaction Mechanism"
   Hironobu Ozawa, Ken Sakai*
   Chem. Commun., 2011, 47, 2227-2242. (Feature Article)
   


7. "A New Type of Electrochemical Oxidation of Alcohols Mediated with a Ruthenium-Dioxolene-Ammine Complex in Neutral Water"
   Hironobu Ozawa, Takami Hino, Hideki Ohtsu, Tohru Wada, Koji Tanaka*
   Inorg. Chim. Acta, 2011, 366, 298-302.
   


6. "Photo-Hydrogen-Evolving Molecular Catalysts Consisting of Polypyridyl Ruthenium(II) Photosensitizers and Platinum(II) Catalysts: Insights into the Reaction Mechanism"
   Hironobu Ozawa, Masayuki Kobayashi, Bijitha Balan, Shigeyuki Masaoka, Ken Sakai*
   Chem. Asian J., 2010, 5, 1860-1869.
   


5. "An Effect of Structural Modification in the Photo-Hydrogen-Evolving Ru(II)Pt(II) Dimers"
   Hironobu Ozawa, Ken Sakai*
   Chem. Lett., 2007, 36, 920-921.
   


4. "Homogeneous Catalysis of Platinum(II) Complexes in Photochemical Hydrogen Production from Water"
   Ken Sakai,* Hironobu Ozawa
   Coord. Chem. Rev., 2007, 251, 2753-2766.
   


3. "Syntheses, Characterization, and Photo-Hydrogen-Evolving Properties of Tris(2,2'-bipyridine)ruthenium(II) Derivatives Tethered to a cis-Pt(II)Cl₂ Unit: Insights into the Structure-Activity Relationship"
   Hironobu Ozawa, Yuki Yokoyama, Masa-aki Haga, Ken Sakai*
   Dalton Trans., 2007, 1197-1206.
   


2. "A Photo-Hydrogen-Evolving Molecular Device Driving Visible-Light-Induced EDTA-Reduction of Water into Molecular Hydrogen"
   Hironobu Ozawa, Masa-aki Haga, Ken Sakai*
   J. Am. Chem. Soc., 2006, 128, 4926-4927.
   


1. "A Tris(2,2'-bipyridine)ruthenium(II) Derivative Tethered to a cis-PtCl₂(amine)₂ Moiety : Syntheses, Spectroscopic Properties, and Visible-Light-Induced Scission of DNA"
   Ken Sakai,* Hironobu Ozawa, Hajime Yamada, Taro Tsubomura, Mariko Hara, Akon Higuchi, Masa-aki Haga
   Dalton Trans., 2006, 3300-3305.