Surface and bulk carrier recombination dynamics of rutile type TiO2 powder as revealed by sub-ns time-resolved diffuse reflection spectroscopy

• Published in: Journal of photochemistry and photobiology. A, Chemistry. Vol. 358; pp. 452 - 458
• Main Authors: Miyasato, Ryo, Sato, Haruyuki, Yano, Toshihiro, Fujiwara, Masazumi, Hashimoto, Hideki
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.05.2018
• Subjects: Carrier dynamics; Photocatalytic water splitting; Target analysis; Titanium dioxide; Transient absorption; Carrier dynamics; Target analysis; Transient absorption; Titanium dioxide; Photocatalytic water splitting
• ISSN: 1010-6030; 1873-2666
• DOI: 10.1016/j.jphotochem.2017.10.054

[Display omitted] •Sub-ns time-resolved diffuse reflection spectra of rutile TiO2 were recorded.•Global and target analysis was applied to the whole observed data-set.•The carriers are identified with their own spectral shapes and decay lifetimes.•Precise features of carriers can be identifiers of the activity of photocatalysts. The carrier dynamics of the semiconductor photocatalyst is the essential concern to clarify the detailed mechanisms of photocatalytic water splitting reactions, which is one of the key issues of artificial photosynthesis to produce solar fuels. In this present study, time-resolved transient diffuse reflection spectra of rutile type TiO2 powder were recorded. Singular value decomposition against whole observed spectral data-set that was followed by global and target analysis has been performed for the first time. A series of examination revealed that the carriers generated in the bulk of TiO2 particle and two distinctive surface carriers are decaying with their own lifetimes. Moreover, the comparison of the measurements both in vacuum and under oxygen atmosphere suggested that the lifetime of surface holes is several tens of nanoseconds. The factors that govern the activity of photocatalyst should be precisely addressed based on thus identified spectral and lifetime features of carriers. Therefore, the present investigation is expected to open the new door to give some good hints when designing more active photocatalysts.