Acetylene polymerization on TiO2 surfaces

Titanium dioxide is an important metal oxide which is frequently used as industrial catalysts and catalyst supports. The acetylene and titanium dioxide reaction is a simple system that can be used as a model for understanding the reactions of transition metal oxides with other more complicated organic substrates. A preliminary accurate study of the relations between particles morphology and surface properties was performed on the TiO2 nanocrystals (P25) combining electron microscopy, FTIR spectroscopy of different CO isotopic mixtures adsorbed at 60 K and DFT calculations. We showed that acetylene is irreversibly interacting with basic sites with formation of colored oligomeric species. The reaction mechanism has been studied in details elucidating the role of the different TiO2 surfaces in the process and the changes in the surface Lewis sites have been monitored at the molecular level for the different steps of the reaction by FTIR spectroscopy of adsorbed CO. This reaction seems to be particularly interesting since these in situ grown colored acetylene polymers can act as potential sensitizers to improve the visible light photoactivity of TiO2