The ability to resolve the individual steps of a heterogeneous chemical reaction using rates determined directly by transient spectroscopy would inform theory and the design artificial photosynthetic systems.  Interfacial hole transfer between n-SrTiO3 and its hydroxilated surface was investigated by surface sensitive transient optical spectroscopy of an in-situ photo-electrochemical cell. The kinetics reveal a single rate constant that exponentially depends on the over-potential for the water oxidation reaction, spanning 1 ns to 10 ps�an assignment made by quantifying voltage and laser illumination induced band edge un-pinning.  Such an observation suggests that, at picosecond time scales, a dominant new intermediate of the water oxidation reaction transforms the initially hydroxilated surface.   The results are used to quantify the activation barrier for hole transfer from the delocalized O 2p valence band to the hydroxilated surface to create the new surface bond.  Current work focuses on identifying the intermediate, possibly a surface oxo, with ultrafast infrared spectroscopy.

Role of fast charge dynamics in heterogeneous catalysis by transient spectroscopy

248th National Meeting (2014)

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