부산대학교 도서관

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.matchemphys.2009.06.013 Byline: Pallavi Shah (a), Deu S. Bhange (a), Aparna S. Deshpande (a), Mukund S. Kulkarni (b), Narendra M. Gupta (a) Keywords: In.sub.2Ti.sub.1-x V.sub.x O.sub.5+[delta] photocatalysts; Microstructure; Optical properties; Luminescence spectroscopy; Structure-activity relationship; Water splitting Abstract: The physicochemical properties of V-doped indium titanates (In.sub.2Ti.sub.1-x V.sub.x O.sub.5+[delta] , 0.0[less than or equal to] x [less than or equal to]0.2) were investigated by using XPS, powder XRD, UV-vis, SEM and luminescence spectroscopy techniques. The Rietveld refinement of XRD data revealed that even though the V-containing samples were isostructural with In.sub.2TiO.sub.5 (orthorhombic space group Pnma), a systematic x-dependent variation was noticeable in the Ti-O bond lengths in [TiO.sub.6] octahedral units, cell parameters and in the value of [delta]. XPS results confirmed the coexistence of V.sup.5+ and V.sup.4+ states, leading thereby to an enhancement in oxygen non-stoichiometry in the doped samples. A loading-dependent progressive shift from 400 to 750nm was also observed in the onset of the absorption edge, indicating a significant narrowing of the band gap. Furthermore, the samples with higher V-content were comprised of the grain clusters having larger size and an irregular shape. The UV-vis, photoluminescence and thermoluminescence studies indicate that the doping-induced lattice defects may give rise to certain closely spaced acceptor/donor energy levels in between the band gap of host matrix. The indium titanates are found to serve as stable photocatalysts for water splitting under visible light, where oxygen was the major reaction product. The role of microstructural and morphological properties in the photocatalytic activity is discussed. Author Affiliation: (a) Catalysis Division, National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411008, India (b) Radiation Safety Systems Division, Bhabha Atomic Research Center, Trombay, Mumbai 400085, India Article History: Received 2 January 2009; Revised 10 June 2009; Accepted 14 June 2009