[油水界面を利用したナノ粒子光捕捉]
水/ヘキサンまたは水/イオン液体からなる液液界面を利用することで、溶液中のTiO2やZnS-AgInS2 (ZAIS)などのナノ粒子や金ナノ粒子の光捕捉に成功しました。
鳥本教授（名古屋大学）、坪井教授（大阪市立大学）、飯田教授（大阪府立大学）、大谷教授（北海道大学）らのグループとの共同研究の成果です。
- 研究成果のポイント
- 低開口数の対物レンズによる弱い集光でもナノ粒子を光捕捉することに成功
- ヘキサン/水界面で光捕捉した八面体金ナノ粒子とZAISナノ粒子からなる複合体が回転する現象を発見
- 水/イオン液体界面で光捕捉した八面体チタニア(TiO2)ナノ粒子に紫外光を照射すると、水中のHAuCl4の光触媒還元反応が起こり金ナノ粒子が生成することを実証（光トラッピングの化学反応応用）
- Optical Trapping of Nanocrystals at Oil/Water Interfaces: Implications for Photocatalysis
- Yasuyuki Tsuboi*, Shota Naka, Daiki Yamanishi, Tatsuya Nagai, Ken-ichi Yuyama, Tatsuya Shoji, Bunsho Ohtani, Mamoru Tamura, Takuya Iida, Tatsuya Kameyama, Tsukasa Torimoto*
- ACS Appl. Nano Mater., 4 (2021), 11743-11752.
- DOI: 10.1021/acsanm.1c02335
Optical trapping of inorganic nanocrystals at oil/water interfaces was investigated under a loose focus condition. The target nanocrystals were octahedral gold nanoparticles (OGPs, 70 nm in size), rice-shaped (10 nm × 20 nm) ZnS-AgInS2 (ZAIS) nanoparticles, and octahedral titania (TiO2) nanoparticles (OTPs, 100 nm). While we were unable to trap these nanoparticles in homogeneous liquids (n-hexane or water), they were successfully trapped at an oil/water interface. We also investigated trapping for a binary system at an interface, where OGPs and ZAIS nanoparticles were dispersed in water (lower layer) and n-hexane (upper layer), respectively. We observed the formation of a complex (hybrid) of an OGP and ZAIS particle trapped at the oil/water interface. Interestingly, the complex particle kept rotating during trapping even under irradiation of linearly polarized light. This phenomenon suggested the spontaneous breakdown of rotational symmetry in the optically coupled nanoparticles. This interfacial trapping technique was applied to a photocatalytic reaction. We observed the generation of Au nanoparticles from OTPs trapped at an interface under UV light irradiation. Liquid/liquid interfaces can strongly assist optical trapping and induce characteristic chemical behavior.
https://pubs.acs.org/doi/10.1021/acsanm.1c02335