Photocatalytic activity of titanium oxide nanoparticles treated by heat-assisted atmospheric pressure oxygen plasma

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K03917
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 14030:Applied plasma science-related
• Research Institution: The University of Tokushima
• Principal Investigator: KAWAKAMI Retsuo 徳島大学, 大学院社会産業理工学研究部(理工学域), 講師 (30314842)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 熱アシスト大気圧酸素プラズマ / アナターゼ結晶型酸化チタン / ルチル結晶型酸化チタン / 光触媒ナノ粒子 / 光分解/光殺菌 / 酸素空孔 / 吸着酸素 / 電荷分離

Outline of Final Research Achievements

Titanium oxide nanoparticles are expected to be used not only as an environmental purification material but also as a renewable energy material. Our study clarified that the thermally assisted atmospheric pressure oxygen plasma treatment proposed by the authors greatly improves the photocatalytic activity under ultraviolet irradiation and visible light irradiation as compared to electric furnace treatment, regardless of the crystallinity. In addition, the photoexcited electrical conductivity, X-ray analysis and photoluminescence analysis revealed the mechanism of photocatalytic activity enhancement. The dominant factor found is the charge separation effect due to upward band bending at the surface, which is a band structure change on the surface promoted by large amounts of introduced oxygen vacancies and adsorbed oxygen species.

Free Research Field

プラズマエレクトロニクス

Academic Significance and Societal Importance of the Research Achievements

我々が提案する熱アシスト大気圧酸素プラズマ処理法は，結晶性に関わらずに，世界的に知られている電気炉法よりも酸化チタンナノ粒子の紫外光および可視光照射下での光触媒反応性を向上させる今までにない新しい知見である．特にその向上機構において，熱と大気圧酸素プラズマとの相乗効果により導入された多くの酸素空孔と吸着酸素がバンド構造変化に関わり光励起キャリア密度が増加する点が学術的に興味深い．また，高価な真空機器を使わず，熱アシスト大気圧酸素プラズマを生成するため，脱炭素化の観点からも優位性の高い光触媒活性化技術であり，社会的課題である環境保全技術や再生可能エネルギー技術の発展に貢献すると考える．