Enhanced Adsorption and Photocatalytic Activities of Co-Doped TiO2 Immobilized on Silica for Paraquat

Abstract

We studied the adsorption and photocatalysis of paraquat in an aqueous solution with cobalt-doped TiO2 supported on mesoporous silica gel. With Co concentration increasing from 0% to 9%, it was found that the TiO2 anatase phase remained unchanged and the Co was uniformly distributed, while the band gap energy decreased from 3.32 eV to 2.64 eV. The drop in band gap energy leads to the Co-TiO2/silica gel photocatalyst oxidation of paraquat to NH4 + and NO3 − products under visible light. Relative to TiO2, the incorporation of Co into TiO2 led to an increase in the adsorption ability against the paraquat. A possible mechanism of the paraquat degradation may be that the paraquat was selectively adsorbed onto the Co-TiO2/silica gel photocatalyst before light irradiation and after that the paraquat was continuously photodecomposed.