Efficient sunlight-driven splitting of water is a potential approach for addressing major challenges in both solar energy conversion and storage. In this paper, we report the preparation and characterization of a triadic water oxidation photoanode consisting of nanoporous films of TiO2, a sensitizer, [Ru(5-crownphen)2(dpb)]2+ (C2P2) and polyoxometalate water oxidation catalyst [{Ru4O4(OH)2(H2O)4}(?-SiW10O36)2]10- (RuPOM). Transient visible and mid-IR absorption spectroscopic studies were carried out to investigate the charge separation dynamic of this system. We observe ultrafast electron transfer from excited C2P2 to TiO2, which competes effectively with electron transfer from C2P2 to RuPOM. Furthermore, the photogenerated oxidized C2P2 can effectively oxidize RuPOM to generate a long-lived charge separate state (TiO2--C2P2-RuPOM+) � the first of the four catalyst oxidation events needed for water oxidation. Ongoing studies are investigating the subsequent catalyst oxidation events. The observed efficient formation and long lifetime of the photo-oxidized catalyst suggest that the reported photoanode is a promising approach for photodriven water oxidation.

Electron transfer dynamics of a water oxidation catalyst photoanode

246th National Meeting (2013)

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