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제122회 대한화학회 학술발표회, 총회 및 기기전시회 안내 Formation of Efficient Visible-Light Photocatalysts by Coupling of Semiconductors

2018년 8월 22일 14시 26분 57초
MAT2-1 이곳을 클릭하시면 발표코드에 대한 설명을 보실 수 있습니다.
금 14시 : 30분
Material Chemisty - Frontier of Materials Chemistry: Photosciences
저자 및
Wan-In Lee
Department of Chemistry, Inha University, Korea
Design of advanced photocatalytic systems, effectively working under visible-light, is essential for practical application of photocatalysts in removing environmental pollutants. To achieve high efficiency, required properties for the photocatalysts will be profound solar light absorption in the visible-range, efficient charge-separation, suitable energy band locations for redox reactions, extended photostability, and others. Since a single semiconductor-based photocatalyst cannot satisfy all of these requirements, a potential strategy will be construction of coupled structures between two or more semiconductors. From this point of view, we explore various types of photocatalytic systems constructed by coupling of semiconductors and their working mechanisms. First of all, according to relative energy band positions between TiO2 and visible-light sensitizers, different types of heterojunction were designed and their visible-light photocatalytic efficiencies were analyzed. In Type-A heterojunction, the conduction band (CB) level of sensitizer is positioned more negative side than that of TiO2, whereas in Type-B system its valence band (VB) level is more positive than that of TiO2. In evolving CO2 from the gaseous 2-propanol (IP) under visible-light irradiation, the Type-B systems such as FeTiO3/TiO2, Ag3PO4/TiO2, W18O49/TiO2, Sb-doped SnO2 (ATO)/TiO2, FeWO4/TiO2 and others demonstrated noticeably higher photocatalytic efficiency than the Type-A such as CdS/TiO2 and CdSe/TiO2. Significantly higher visible-light photocatalytic activity of Type-B heterojunction structures could be explained by inter-semiconductor hole-transfer mechanism between the VB of sensitizer and that of TiO2. In addition, p-n junction or Z-scheme based visible-light photocatalysts were designed and their photocatalytic mechanisms including charge-flow pathways are discussed intimately in this work.