Covalent Attachment of a Rhenium Bipyridyl CO2Reduction Catalyst to Rutile TiO2 Probed by SFG Tianquan Lian, Department of Chemistry, Emory University, Atlanta, GA 30322 SFG spectra and a computed structure of ReC0A on TiO2
¾Vibration Sum Frequency Generation (SFG) spectroscopy is a surface selective and in situ technique for recording vibration spectra of adsorbates at interfaces relevant to solar energy conversion, such as in solar cells and in photoelectrochemical cells. ¾The binding geometry of ReC0A (a model CO2 reduction catalyst) on the Rutile TiO2 (001) surface has been determined by a combined SFG measurement and computational modeling study.
Amplitude {Re[X(2)], Im[X(2)]
Heterodyne detected SFG Spectra: 0.06
(2)
Re[χ ] Im[χ(2)]
0.04 0.02 0.00 -0.02 -0.04 1800 1850 1900 1950 2000 2050 2100 IR Wavelength (cm-1)
¾ heterodyne detection of SFG signal allows a) the measurement of sub-monolayer of molecules on a semiconductor surface – important for identifying catalytic intermediates; b) improvement of signal-tonoise ratio and reduce data averaging time – essential for using SFG to probe interfacial dynamics in a pump/probe experiment; and c) the determination of both the real and imaginary part of the second order susceptibility – simplifying spectral assignment.
