Heterogeneous catalysis and dye-sensitized solar cells require a large surface area to be effective. This is often accomplished by using functionalizing colloidal a TiO2 sol-gel, where the molecular catalyst or dye is bonded to the nanostructure TiO2 surface. While dramatically improving the efficiency, such systems are very complex and exhibit a large structural heterogeneity. This makes it difficult to gain a detailed molecular-level understanding of the heterogeneous electron transfer processes using conventional spectroscopy that averages over this heterogeneity. Furthermore, this complicates direct comparisons to theoretical calculations that require a well-defined surface structure. Surface-specific spectroscopy exhibit monolayer sensitivity and thus facilitates studying catalysts and dyes on single-crystalline TiO2 surfaces with well-defined orientations. We use static and transient sum-frequency generation (SFG) spectroscopy to study the structure and vibrational dynamics of the catalysts and dyes and how these depend on the surface structure of TiO2. We initially focus on rhenium carbonyl catalysts and the classical N3 dye [Ru(dcbpy)2(NCS)2] and study the orientation and vibrational dynamics of the catalysts/dyes on different single crystalline TiO2 surfaces.

Vibrational dynamics of dyes and catalysts on single crystalline TiO2 surfaces

248th National Meeting (2014)

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