Fundamental studies of to CO2 reduction catalysts bound to electrode surfaces rely upon the structural characterization and catalyst orientation relative to the electrode-electrolyte interface. Here, we focus on the analysis of a highly efficient ReI(R2-bpy)(CO)3Cl electrocatalysts bound to Au and to TiO2 electrode surfaces. We combine DFT, cyclic voltammetry, and infrared-visible sum frequency generation (IR-SFG) spectroscopy to resolve the arrangement of the electrocatalyst at the electrode interface as reported by characteristic SFG vibrational modes. Cyclic voltammetry demonstrates that the catalysts are active towards CO2 at the third reductive wave. Probing this state by infrared-spectroelectrochemistry and bulk electrolysis reveals that the complexes are electrocatalysts that allow for the reduction of CO2 to carbon monoxide and carbonate. In one case (R = Au), the cyano-substituted molecule has been adsorbed onto an Au surface and found to bind through one arm. In the other case (R = COOH), it has been found that the SFG signal shows an anisotropic distribution for the (110) surface of rutile TiO2, but not for the (001) surface, which is explained by preferential binding along one crystal axis due to additional favorable hydrogen bonding between the carboxylate groups and surface waters.

Determination of orientation of bipyridine Re(I) fac-tricarbonyl electrocatalysts on Au and on TiO2 surfaces through computational SFG spectroscopy

251st National Meeting (2016)

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