Investigation of cation (Sn2+) and anion (N3-) substitution in favor of visible light photocatalytic activity in the layered perovskite K2La2Ti3O10

Noticeable lowering of the energy gaps have been achieved for the layered perovskite K2La2Ti3O10 as a result of the attempts made to incorporate Sn2+ and N3- ions. Incorporation of Sn2+ ions was carried out by the ion-exchange reaction of K2La2Ti3O10 with aqueous tin(II) chloride solution. Nitrogen incorporation was attempted by the solid state reaction of the parent oxide with urea around 400 degrees C in air. The resultant oxides have been characterized by power X-ray diffraction, UV-visible diffuse reflectance spectroscopy, and Fourier transform infrared spectroscopy. Room temperature ion-exchange was sufficient to introduce Sn2+ ions with the resulting product of composition (Sn0.45K0.2 H-0.9)La2Ti3O10 center dot H2O. Visible light absorption was observed with the absorption edge red shift of similar to 100 nm from that of the parent K2La2Ti3O10. The lowering of the band gap was as expected by the contribution of Sn 5s orbitals to the O 2p orbitals in the formation of the valence band. Nitridation using urea resulted not only in nitrogen doping but with the additional sensitization by the presence of carbon nitride (CN) polymers, which again resulted in visible light absorption. The product oxides obtained as a result of cation and anion intended substitutional studies have been found to be useful for the visible light photocatalytic decomposition of organic dyes such as rhodamine B. (C) 2011 Elsevier B.V. All rights reserved.