FTIR study of interactions of ethyl iodide with powdered TiO2
Abstract
The
adsorption, thermal reactions, and photochemistry of C2H5I have been studied on TiO2 by Fourier-transformed
infrared spectroscopy. C2H5I is adsorbed on TiO2 and remains intact at 35°C. However, it decomposes
to form C2H5O(a) at temperatures below 200°C in vacuum. It is found that this decomposition process is enhanced
by the presence of isolated surface hydroxy groups. In the study of the thermal reaction of C2H5I on TiO2
in a closed IR cell without O2, ethylene is the only gas product detected. However in the presence
of O2, in addition to ethylene, H2O, CO and CO2 are generated together with surface species probably derived
from the adsorption of another product of acetaldehyde. In the photochemistry of C2H5I on TiO2 in forming
surface formate and acetate, which are probably produced ia
acetaldehyde intermediate, O2 plays an essential role.
It is likely that the photoreaction
is initiated
by O2−, generated
from photoelectron capture by adsorbed O2.