Infrared studies of a hybrid CO2-reduction photocatalyst consisting of a molecular Re(I) complex grafted on Kaolin

• A hybrid photocatalyst was synthesized by grafting a molecular Re(I) complex on Kaolin.
• Interactions between CO2 and the hybrid photocatalyst was investigated with in situ infrared spectroscopy.
• The formation of two surface Re(I) complexes relevant to CO2-reduction catalysis was identified with infrared studies.

We previously investigated hybrid photocatalysts prepared by grafting Re(bpy)(CO)3Cl, where bpy = 2,2′-bipyridine, onto different solid-state surfaces. The hybrid photocatalysts lost reactivity in solar CO2 reduction although the diimine-tricarbonyl coordination of Re(I) was maintained after photocatalysis. In this study, we synthesized a hybrid photocatalyst by grafting the Re(I) complex on Kaolin and further explored the interactions between CO2 and the hybrid photocatalyst using in situ infrared spectroscopy. Our infrared studies at the gas–surface interface revealed the formation of two surface Re(I) complexes in the presence of CO2 and triethanolamine, a basic electron donor. One of the surface Re(I) complexes is considered as the real catalyst for CO2 reduction, while the other complex might be associated with the deactivation of our hybrid photocatalysts in CO2 reduction. The layered structure of Kaolin likely contributed to the formation of a surface Re(I)-OH complex.

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