14 October 2004 Photoinduced redox reaction of carboxylates on TiO2(110)
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The adsorption and ultraviolet photolysis at 300 K of trimethylacetate, (CH3)3CCOO-, on TiO2(110) has been explored by combining scanning tunneling microscopy, isothermal reaction mass spectrometry and electron energy loss spectroscopy. The photolysis, initiated by forming excited electrons and holes in the oxide, is dominated by ejection of CO2 and C4H8 with no evidence for retention of carbon-containing species. The chemistry is the result of holes extracting electron density from the pi-orbital of a carboxyl group leading to decarboxylation. The accompanying electron is trapped as Ti3+ at the surface. These trapped species compete for holes and inhibit the hole-mediated decarboxylation. The trapped electrons can be removed by exposure to O2 at 300 K leading to a transient acceleration of the reaction rate after resuming photolysis. Under aerobic conditions, arriving O2 scavenges trapped electrons as they are formed reducing the degree of quenching and increasing the rate of trimethylacetate consumption without changing the products.
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J. M. White, J. M. White, Michael A. Henderson, Michael A. Henderson, Hiroshi Uetsuka, Hiroshi Uetsuka, Hiroshi Onishi, Hiroshi Onishi, } "Photoinduced redox reaction of carboxylates on TiO2(110)", Proc. SPIE 5513, Physical Chemistry of Interfaces and Nanomaterials III, (14 October 2004); doi: 10.1117/12.558940; https://doi.org/10.1117/12.558940

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