Abstract
In this letter, we report the observation of an ultraviolet (UV) photoluminescence (PL) emission at around 330 nm in porous silica prepared by the sol–gel process. Upon a posttreatment which leads to OH adsorption, the intensity of the observed UV PL emission increases significantly. It is shown that this behavior is associated with the increase of OH groups adsorbed on the surface of porous silica. We suggest that the observed UV PL emission originates from the nonbridging oxygen hole centers generated from surface hydroxyls. The mechanism of the UV PL emission is expressed tentatively by combining the nonbridging oxygen centers charge modification model and the vibrative absorption of a SiO2 network containing water.
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