Photocatalytic reduction of carbon dioxide with water using InNbO4 catalyst with NiO and Co3O4 cocatalysts

InNbO4 was prepared by the solid-state reaction method. Various cocatalysts were added on InNbO4 by the incipient-wetness impregnation method. The effects of co-catalyst and pretreatment conditions on the photocatalytic activity of InNbO4 for photoreduction of carbon dioxide were investigated. NiO-InNbO4 and Co3O4-InNbO4 were pretreated by reduction at 500 degrees C for 2 h and subsequent oxidation at 200 degrees C for 1 h. The catalysts were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and UV-vis diffuse reflectance spectroscopy. The characterization results of NiO-InNbO4 catalysts after pretreatment showed the presence of highly crystalline NiO and monoclinic Nb2O5. NiO-InNbO4 with reduction-oxidation pretreatment exhibited the highest activity due to the presence of core-shell type Ni-0 and NiO on the surface and the presence of a small amount of Nb2O5 as a promoter. (C) 2012 Elsevier Ltd. All rights reserved.