Preparation, Characterisation, and Photocatalytic Behaviour ofCo-TiO2with Visible Light Response

Abstract

The preparation of cobalt-modifiedTiO2(Co-TiO2) was carried out by the incipient impregnation method starting from commercialTiO2(Degussa, P-25) and cobalt acetate. XPS data show that cobalt is incorporated as divalent ion, and it is likely present within few subsurface layers. No appreciable change in structural-morphologic properties, such as surface area and anatase/rutile phase ratio, was observed. Conversely, Co addition brings about conspicuous changes in the point of zero charge and in surface polarity. Diffuse reflectance spectra feature a red shift in light absorption that is dependent on the amount of cobalt. The influence of cobalt addition on the performance ofTiO2as a photocatalyst in the degradation of 4-chlorophenol and Bisphenol A is investigated. The results show that the modified oxide presents a higher photoactivity both for illumination with UV-visible (λ>360 nm) and visible light (λ>420 nm;λ>450 nm), and that this enhancement depends on the amount of the added species and on the final thermal treatment in the preparation step. We also show that Co-TiO2is a more active catalyst than pureTiO2for the reduction ofO2in the dark, which is an important reaction in the overall photocatalytic processes.