122nd General Meeting of the KCS

Type Symposium
Area Frontier of Materials Chemistry: Photosciences
Room No. Room 322
Time FRI 14:30-:
Code MAT2-1
Subject Formation of Efficient Visible-Light Photocatalysts by Coupling of Semiconductors
Authors Wan-In Lee
Department of Chemistry, Inha University, Korea
Abstract 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.
E-mail wanin@inha.ac.kr