CeO2/TiO2 nanostructures enhance adsorption and photocatalytic degradation of organic compounds in aqueous suspension

Abstract Mixed oxide interfaces are critical in the delivery of active components in photocatalytic processes. Cerium doped TiO 2 photocatalysts were prepared using a hydrothermal route to manipulate the morphology of the photocatalyst and improve the interaction between CeO 2 and TiO 2 nanoparticles. These changes were compared with the photocatalytic activity and adsorption capacity of the solids. The photocatalysts were used to degrade polyvinylpyrrolidone (PVP) and methylene blue (MB) as test compounds. A low photodegradation rate of PVP (0.0001 min −1 and 0.0005 min −1 under visible and UV light, respectively) was observed using Ce-doped photocatalysts, with no adsorption. The high adsorption capacity of MB (34.46 mg g −1 ) proved that the local morphology of the nanostructured CeO 2 /TiO 2 photocatalysts is more important than the amount of CeO 2 in the sample, and the main role of the CeO 2 on mixed photocatalysts is to improve thermal stability during the synthesis. XRD, XPS, BET surface area, UV–vis and TEM techniques confirmed this conclusion. The rate of degradation of MB by the Ce-doped photocatalyst decreased dramatically when using the singlet oxygen scavenger L-Histidine (0.0214 min −1 to 0.0001 min −1 ), indicating a photocatalysis sensitized by the dye, under visible and UV light.