2-Propanol photodegradation over lead niobates under visible light irradiation

Two binary lead niobates, viz, Pb3Nb2O8 and Pb3Nb4O13, had been developed as visible-light-sensitive photocatalysts. Their physical characteristics were examined by techniques such as XRD, UV-vis reflectance spectroscopy and SEM; the photocatalytic activities of several samples were investigated for 2-propanol degradation in gas phase. Compared to pure Nb2O5, the hybridization of Pb 6s(2) and O 2p(6) orbitals notably pushed up the position of the valence band top, and narrowed the band gap of lead niobates. Due to the appropriate crystal structure and energy band structure, Pb3Nb4O13 performed much better than Pb3Nb2O8 for 2-propanol photodegradation. Different preparation methods were also adopted to prepare the Pb3Nb4O13 samples. Compared to the solid-state reaction method (SSR), the co-precipitation method (CP) created a high homogeneity in the precursor powder, which notably decreased the calcination temperature required for crystal formation. The so-obtained Pb3Nb4O13(CP) photocatalyst possesses much greater surface area than its Pb3Nb4O13(SSR) counterpart, and exhibited notably improved photocatalytic activity for 2-propanol degradation as a result. (c) 2007 Elsevier B. V. All rights reserved.