Photoluminescence and photocatalytic activity of MgO powders

Abstract

Photoluminescence properties and photocatalysed isomerization reaction of 2-butenes have been investigated using a standard JRC-MgO-I sample. The effects of the degassing temperature of the MgO sample and of the added quencher molecules such as O 2, CO, and H 2 indicated that the photoluminescence with a lifetime of 10 −4 sec is the radiative decay process from the charge transfer excited complex, (Mg LC + − O LC − ) ★ associated with the lower co-ordinated surface ions. It has been found that U.V. irradiation of degassed MgO samples in the presence of 2-butenes leads catalytically to trans — cis geometrical isomerization reaction with high efficiency, together with less efficient double bond shift isomerization reaction. The addition of CO or O 2 led to the inhibition of this photocatalysed isomerization as well as the photoluminescence of MgO samples. A complete parallel between the intensity of photoluminescence and the rate of photocatalysed isomerization of butenes indicated that the lower co-ordinated surface ions play a significant role in the photocatalytic activity of degassed MgO powders.