Structural and electronic properties of platinum doped titanium dioxide

C.I.N. MORGADE; G.F. CABEZA; C. VIGNATTI; N.J. CASTELLANI

Santiago

Congreso; 10th. Congress of the World Association of Theoretical and Computational Chemists; 2014

Pontificia Universidad Católica de Chile

The interaction between a noble metal as platinum (Pt) and a reducible oxide such as titania (TiO2) is interesting not only for its known properties as photocatalyst [1], but also for its important applications in heterogeneous catalysis. It is known that when Pt is deposited on TiO2 some metal is dissolved into the bulk altering its properties [2]. The structural and electronic properties of Pt-doped titania were theoretically calculated using Density Functional Theory (DFT+U). For that purpose both polymorphs, anatase (A) and rutile (R), were modeled by substituting a Ti for Pt in the unit cell (at 8.3 % and 16.7 % concentrations, respectively). To complete the analysis, the corresponding Bader charges for A and R were calculated. From the evaluation of the calculated values, we observe a lower ionic character between metals (Pt and neighbours Ti) and oxygen around the defect. Based on the analysis of the local density of states (LDOS) between pure and doped systems, we conclude that: the valence band width increased by ~ 3 eV, both conduction and valence bands are shifted to the left about 0.3 eV and new hybrid states appear near the conduction band (CB) due to Pt incorporation. The presence of these states produces a significant narrowing of the BG (97.5 % for A and 86.2 % for R). [1] A. Zaleska, Recent Patents on Eng. 2 (2008) 157. [2] Ch. Vignatti, M. S. Avila, C. R. Apesteguía, T. F. Garetto, Int. J. of Hyd. Energy 35 (2010) 7302.