Efficient photocatalytic reactions utilizing vapor bubble formation under sunlight irradiation

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K21932
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 19:Fluid engineering, thermal engineering, and related fields
• Research Institution: Kyoto University
• Principal Investigator: Namura Kyoko 京都大学, 工学研究科, 助教 (20756803)
• Project Period (FY): 2019-06-28 – 2022-03-31
• Keywords: 水蒸気バブル / 光熱変換 / 光触媒反応 / 太陽光

Outline of Final Research Achievements

The purpose of this research was to effectively utilize the energy of the portion of sunlight in the visible to near-infrared wavelength region. When light in this wavelength range is focused on a photothermal conversion thin film, localized heat is generated, which can produce microbubbles in water. Because the bubble is exposed to a steep temperature gradient, it experiences the surface tension gradient and significant volume changes. As a result, strong mixing flow is generated around the bubble. In this study, we clarified the conditions under which such a flow is generated, and also succeeded in controlling the flow under uniform light irradiation. It was also found that this flow can efficiently mix the ambient fluid. This phenomenon is useful for promoting photocatalytic reactions that utilize mainly ultraviolet light.

Free Research Field

表面・界面・薄膜工学

Academic Significance and Societal Importance of the Research Achievements

本研究では、光熱変換・光触媒薄膜に擬似太陽光やレーザー光を照射することで、バブルの挙動の詳細な研究や流体攪拌性能の評価などを行った。得られた成果は太陽光を使った高度な流体制御を可能にし、今後の太陽光を利用した光触媒反応の応用方法を広げることができると期待される。また本成果は光触媒反応だけでなく、マイクロ水冷、洗浄、生化学分析、創薬、など、流体を用いるあらゆるデバイス開発においても有用な知見を与えた。さらに、小さな領域における熱と流体の動きの理解を深めて分野の発展に貢献した。