Structure of surface tantalate species and photo-oxidation of carbon monoxide over silica-supported tantalum oxide

Abstract

Tantalum oxide (10 wt.% as Ta₂O₅) supported on silica was prepared and the structure and the photo-oxidation of carbon monoxide over the catalyst sample were investigated. XAFS analysis showed that surface tantalate is a TaO₄ tetrahedral species with a Ta2O bond which is a photoactive center. The initiation of the photo-oxidation of carbon monoxide is the photoadsorption of an oxygen molecule on the catalyst sample, elucidated by photoluminescence. EPR spectroscopy showed that the photo-excited center interacts with an oxygen molecule to form a T-type ozonide ion. A carbon monoxide ion attacks the ozonide ion to form an [O₃–CO]^- paramagnetic intermediate to lead the production of carbon dioxide.