Solid-state NMR studies of the adsorption and photooxidation of ethanol on mixed TiO 2–SnO 2 photocatalysts

Abstract

In situ solid-state NMR methodologies have been used to investigate the photocatalytic oxidation of ethanol (CH 3CH 2OH) over a series of SnO 2-based photocatalysts. The adsorption of ethanol on commercially available SnO 2 powder was studied using both cross-polarization 13C NMR and REDOR experiments, and showed the formation of two surface ethanol species, hydrogen-bonded ethanol at surface hydroxyl groups and ethanol chemisorbed to the SnO 2 surface (Sn–OCH 2CH 3). 13C NMR of the adsorbed ethanol was used to characterize the surface of monolayer SnO 2–TiO 2 coupled photocatalysts supported on porous Vycor glass. In situ solid-state NMR studies showed that the photooxidation of ethanol over the monolayer photocatalysts was slower than that over a supported TiO 2 monolayer photocatalyst due to the build-up of reaction intermediates such as acetic acid on the catalyst surface. 119Sn NMR experiments characterized the tin species on the porous Vycor glass support.