INFRARED SPECTROSCOPIC STUDY OF THE PHOTOINDUCED ACTIVATION OF CO2 ONTIO2 AND RH TIO2 CATALYSTS/

The effect of illumination on the activation of CO2 was investigated a t 190 K on oxidized, evacuated, and reduced TiO2 and Rh/TiO2 by means of Fourier transform infrared spectroscopy. The main effect observed f or pure titania was an enhancement of the intensity of bands at 1640 a nd 1219 cm(-1) due to bent CO2. On Rh/TiO2 the photoinduced dissociati on of CO2 also occurred, as indicated by the development of CO bands a t 2020-2040 cm(-1). It is assumed that the CO2 on Rh/TiO2 is bonded to the surface with both C (linked to a Rh atoms) and one of the O atoms (linked to the oxygen vacancy of titania), and an extended charge tra nsfer induced by illumination leads to the cleavage of a C-O bond.