|Research Field(Keyword & Summary)
- (1) Photocatalytic H2/oxidant production
Simultaneous photocatalytic production of H2 and inorganic oxidants such as hypochlorous acid (HClO) as a value-added oxidation reagent compared with O2 on a semiconductor photocatalysts by using solar light is one of the breakthrough technologies for a sustainable and economical energy conversion process. However, the selective oxidants production systems using visible-light responsible photocatalysts has not been much establisted. To overcome the issue, we are investigating photocatalyst materials (including its synthesis process), and various systems (particles suspension, electrode, panel, etc.) for efficient oxidants production.
- (2) Photocatalytic oganic synthesis
One of the most attractive targets of photocatalysis using semiconductor materials is its application to organic syntheses, as well as solar-energy conversion. Photocatalytic organic synthesis on semiconductor materials may be one of the candidates for environmentally benign process, because most of photocatalytic reactions can proceed efficiently even in aqueous suspensions at room temperature, by utilizing the clean, renewable solar light as the driving force. Although the famous semiconductor TiO2 has been reported to be photo-active for organic conversion, poor selectivity, and lack of utilization of visible-light, hinder its application. To overcome the issues, we are investigating photocatalyst materials and systems for efficient organic synthesis.
- (3) Electrochemical oxidant production
Production of inorganic oxidants via electrolysis is also one of the environmental friendly, zero emission of carbon dioxide if this process combined with renewable energy sources. We are designing the material, tuning morphology and particle size, and controlling preparation process of the electrodes to realize efficient electrochemical activity. In addition, our group also approaches on computational study for a better material design of electrocatalysts with various collabolators.
- 1. “Facile water-based preparation of Rh-doped SrTiO3 nanoparticles for efficient photocatalytic H2 evolution under visible light irradiation” S. Okunaka, H. Tokudome, R. Abe, J. Mater. Chem. A, 3, pp.14794–14800, 2015
- 2. “Preparation of fine particles of sheelite-monoclinic phase BiVO4 via an aqueous chelating method for efficient photocatalytic oxygen evolution under visible-light irradiation”, S. Okunaka, H. Tokudome, Y. Hitomi, R. Abe, J. Mater. Chem. A, 4, pp.3926–3932, 2016
- 3. “Printable photocatalyst sheets incorporating a transparent conductive mediator for Z-scheme water splitting” , Q. Wang*, S. Okunaka*, H. Tokudome*, T. Hisatomi, M. Nakabayashi, N. Shibata, T. Yamada, K. Domen (*These authors contributed equally), Joule, vol.2, 12, pp.2667–2680, 2018
- 4. “Green light active photocatalyst for complete oxidation of organic molecules”, Y. Yang, A. Yamaguchi, H. Jiang, A. Kooy, S. Okunaka, M. Hosogai, H. Tokudome, M. Miyauchi, Chem. Commun., 56, pp. 9210–9213, 2020
- 5. “Z-Scheme Water Splitting under Near-Ambient Pressure using a Zirconium Oxide Coating on Printable Photocatalyst Sheet”, S. Okunaka, H. Kameshige, T. Ikeda, H. Tokudome, T. Hisatomi, T. Yamada, K. Domen ChemSusChem, 13, pp. 4906–4910, 2020
- 6. “Selective oxidation of toluene to benzaldehyde over Pd/BiVO4 particles under blue to green light irradiation” S. Okunaka, H. Tokudome, Y. Hitomi, J. Catal, 391, pp. 480–484, 2020
- 7. “Improvement of photoelectrochemical HClO production under visible light irradiation by loading cobalt oxide onto a BiVO4 photoanode”, S. Okunaka, Y. Miseki, K. Sayama, Catal. Sci. Technol., 11, pp. 5467–5471, 2021
- 8. “Charge carrier mapping for Z-scheme photocatalytic water-splitting sheet via categorization of microscopic time-resolved image sequences”, M. Ebina, T. Ikeda, S. Okunaka, H. Tokudome, K. Domen, K. Katayama, Nat. Commun., 12, pp. 3716–3724, 2021
- 9.“Photocatalytic solar hydrogen production from water on a 100 m2-scale”, H. Nishiyama, T. Yamada, M. Nakabayashi, Y. Maehara, M. Yamaguchi, Y. Kuromiya, H. Tokudome, S. Akiyama, T. Watanabe, R. Narushima, S. Okunaka, N. Shibata, T. Takata, T. Hisatomi, K. Domen, Nature, 598, pp. 304–307, 2021
- 10. “Boosting the visible-light-induced toluene oxidation via synergistic effect between nanoparticulate Pd/BiVO4 photocatalyst and a cyclic nitroxyl redox mediator”, S. Okunaka, Y. Hitomi, H. Tokudome, J. Catal., 414, pp. 137–142, 2022