Evidence for Conduction Band-Mediated Two-Electron Reduction of a TiO2-Bound Catalyst Triggered by Visible Light Excitation of Co-Adsorbed Organic Dyes
Journal article, 2018

Here, we report direct spectroscopic evidence of a visible light-induced two-electron-transfer reaction to a molecular model catalyst, facilitated by conduction band mediation. Using a simple, yet remarkably reproducible, co-sensitization approach, we anchored dyes and catalysts to mesoporous TiO2 thin films, at dye/catalyst ratios of 30:1, 15:1, and 8:1. The distinct optical spectroscopic signatures of different redox states of the catalyst used, Co-protoporphyrin IX, allows for transient absorption detection of intermediate and final photoproducts in the photoexcited co-sensitized dye-TiO2-catalyst assemblies. We show that by tuning the dye/catalyst ratios, control over whether photoexcitation results in one or two electrons being transferred to the catalyst is achieved. The two-electron-transfer process is favored by a large excess of photosensitizer compared to catalyst.

Author

Valeria Saavedra

Chalmers, Chemistry and Chemical Engineering, Chemistry and Biochemistry, Physical Chemistry

Elin Sundin

Chalmers, Chemistry and Chemical Engineering, Chemistry and Biochemistry, Physical Chemistry

Maria Abrahamsson

Chalmers, Chemistry and Chemical Engineering, Chemistry and Biochemistry

Journal of Physical Chemistry C

1932-7447 (ISSN) 1932-7455 (eISSN)

Vol. 122 45

Subject Categories

Atom and Molecular Physics and Optics

Other Chemistry Topics

Condensed Matter Physics

DOI

10.1021/acs.jpcc.8b07669

More information

Latest update

12/10/2018