Characterization of Ag-TiO₂ Electronic Structures and Nanotubes Based on First-Principles Calculation

Abstract:

In this manuscript, we report the simulation of electronic structures of TiO₂ doped with Ag using first-principles calculation, based on the density functional theory (DFT) The mechanism to improve the visible-light photocatalytic activity for TiO₂ doped with Ag. E_F was displaced into the valence band (VB), narrowing the band gap. An independent energy band was also introduced above the VB and an energy band with the width of 0.9 eV is introduced under the conduction band (CB), also resulting in the narrowing of the band gap. New VB and CB were formed by three orbitals O-2p, Ti-3d and Ag-4d. Composite TiO₂ nanotubes with Ag-doping were synthesized using the alkaline fusion and hydrothermal method under ambient atmosphere. XRD results indicated composite Ag-TiO₂ nanotubes ranging from the single anatase phase to the anatase and rutile mixed phase. XPS showed an increase in the surface acidity and photo catalytic activity of TiO₂ nanotubes due to the presence of OH radicals. Furthermore Ag-doping also facilitated the separation of photo-holes and photo-electrons and enhanced the optical properties.

• Periodical: Key Engineering Materials (Volumes 609-610)
• Pages: 20-25
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.609-610.20
• Online since: April 2014
• Authors: Jing Ling Li, Xiao Xia Cao, Bo Wu, Hua Liang Yu, Yong Jiang Gan
• Keywords: Ag-Doped, Characterization, First-Principles Calculation, TiO₂ Nanotubes (NTs)

References

[1] Ghicov A., Macak J. M., Tsuchiya H., et al. Ion implantation and annealing for an efficient N-doping of TiO2 nanotubes, Nano Lett., 6 (2006) 1080-1082.

DOI: 10.1021/nl0600979

[2] Zhang F. J., Chen M. L., and Oh W. C. Photoelectrocatalytic properties of Ag-CNT / TiO2 composite electrodes for methylene blue degradation, New Carbon Materials, 25 (2010) 348-356.

DOI: 10.1016/s1872-5805(09)60038-x

[3] Lees A. C., Kleverlaan C. J., Bignozzi C. A., et al., Photophysical properties of TiO2 surfaces modified with dinuclear Ru and RuOs polypyridyl complexes, Inorg. Chem. 40 (2001) 5343-5349.

DOI: 10.1021/ic0102743

[4] Gong J Y, Pu W H, Yang C Z, et al. A simple electrochemical oxidation method to prepare highly ordered Cr-doped titania nanotube arrays with promoted photoelectrochemical property. Electrochimica Acta, 2012, 68: 178~183.

DOI: 10.1016/j.electacta.2012.02.049

[5] Batzill M., Hebenstreit E. L.D., Hebenstreit W., et al., Influence of subsurface, charged impurities on the adsorption of chlorine at TiO2, Chem. Phys. Lett. 367 (2003)319-323.

DOI: 10.1016/s0009-2614(02)01635-4

[6] Hippe C., Wark M. , Lork E., et al., Platinum-filled oxide nanotubes, Microporous Mesoporous Mater 31(1999) 235-241.

DOI: 10.1016/s1387-1811(99)90074-4

[7] Li X., Finnis M.W., He J., et al., Evaluation of Correction Schemes for Charged Point Defects in Rutile TiO2 Calculated by Density Functional Theory, Acta Mater. 57 (2009)5882-5891.

DOI: 10.1016/j.actamat.2009.08.014

[8] Hou X.G., Liu A.D., Huang M. D., Liao B. and Wu X.L., (2009)Chinese Phys. Lett., 26: 077106.

[9] X. Y. Wu, B. Liao, H. Liang, X. Zhang and A. D. Liu, Theoretic and experimental studies on Titania nanotube doped with Ag metal ions, Chin. J. Struct. Chem., 9(2011) 1332-1334.

[10] Li J. L., Chen W. Z., Bi J. J., et al., Synthesis of Ag-TiO2 nanotubes in ambient atmosphere and kinetics of photocatalytic reaction, Chin. J. Sens. Actuators. 23(2010) 617-620.

[11] Shockley W., Read W.T., Jr., Statistics of the recombinations of holes and electrons, Phys. Rev. 87(1952)835-842.

DOI: 10.1103/physrev.87.835

[12] Hall R.N., Electron-Hole Recombination in Germanium, Phys. Rev. 87 (1952)387.

[13] Kronik L., Shapira Y.  Surface photovoltage phenomena: theory, experiment, and applications, Surf. Sci. Rep., 37: (1999)1-206.

[14] Zhang F. X, Pi Y., Cui J., et al. Unexpected selective photocatalytic reduction of nitrite to nitrogen on silver-doped titanium dioxide. J. Phys. Chem. C., , 111(2007)3756-3761.

DOI: 10.1021/jp067807j

[15] Lin W. C., Chen C. N., Tseng T. T., et al. Micellar layer-by-layer synthesis of TiO2/Ag hybrid particles for bactericidal and photocatalytic activities. J. Euro. Ceramic. Soc., 30( 2010)2849-2857.

DOI: 10.1016/j.jeurceramsoc.2009.12.016

[16] Su W., Wei S S, Hu S Q, et al. Preparation of TiO2/Ag colloids with ultraviolet resistance and antibacterial property using short chain polyethylene glycol. J. Hazardous Mater., 172(2009)716-720.

DOI: 10.1016/j.jhazmat.2009.07.056