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Linked References

1. D. Lawless, Photophysical studies on materials of interest to heterogeneous photocatalysis and to imaging science: CdS quantum dots, doped and undoped ultrasmall semiconductor ${\text{TiO}}_{\text{2}}$ particles, and silver halides, M.S. thesis, Concordia University, Montreal, Canada, 1993.
2. M. Anpo and M. Takeuchi, “The design and development of highly reactive titanium oxide photocatalysts operating under visible light irradiation,” Journal of Catalysis, vol. 216, no. 1-2, pp. 505–516, 2003. View at Publisher · View at Google Scholar
3. S. Sato, “Photocatalytic activity of nitrogen oxide (${\text{No}}_x$)-doped titanium dioxide in the visible light region,” Chemical Physics Letters, vol. 123, pp. 126–128, 1986. View at Publisher · View at Google Scholar
4. R. Asahi, T. Morikawa, T. Ohwaki, K. Aoki, and Y. Taga, “Visible-light photocatalysis in nitrogen-doped titanium oxides,” Science, vol. 293, pp. 269–275, 2001. View at Publisher · View at Google Scholar · View at PubMed
5. T. Morikawa, R. Asahi, T. Ohwaki, K. Aoki, and Y. Taga, “Band-gap narrowing of titanium dioxide by nitrogen doping,” Japanese Journal of Applied Physics, Part 2: Letters, vol. 40, no. 6 A, pp. L561–L563, 2001. View at Publisher · View at Google Scholar
6. X. Chen and S. S. Mao, “Titanium dioxide nanomaterials: synthesis, properties, modifications and applications,” Chemical Reviews, vol. 107, no. 7, pp. 2891–2959, 2007. View at Publisher · View at Google Scholar · View at PubMed
7. X. Chen, Y. Lou, S. Dayal, et al., “Doped semiconductor nanomaterials,” Journal of Nanoscience and Nanotechnology, vol. 5, no. 9, pp. 1408–1420, 2005. View at Publisher · View at Google Scholar
8. N. Serpone, A. V. Emeline, V. N. Kuznetsov, and V. K. Ryabchuk, “Second generation visible-light-active photocatalysts: preparation, optical properties and consequences of dopants on the band gap energy of ${\text{TiO}}_{\text{2}}$,” in Environmentally Benign Catalysts—Applications of Titanium Oxide-Based Photocatalysts, M. Anpo and P. V. Kamat, Eds., Springer, New York, NY, USA, 2007.
9. H. M. Yates, M. G. Nolan, D. W. Sheel, and M. E. Pemble, “The role of nitrogen doping on the development of visible light-induced photocatalytic activity in thin ${\text{TiO}}_{\text{2}}$ films grown on glass by chemical vapour deposition,” Journal of Photochemistry and Photobiology A: Chemistry, vol. 179, no. 1-2, pp. 213–223, 2006. View at Publisher · View at Google Scholar
10. H. Noda, K. Oikawa, T. Ogata, K. Matsuki, and H. Kamata, “Preparation of titanium(IV) oxides and its characterization,” Bulletin of the Chemical Society of Japan, pp. 1084–1090, 1986.
11. N. C. Saha and H. G. Tompkins, “Titanium nitride oxidation chemistry: an x-ray photoelectron spectroscopy study,” Journal of Applied Physics, vol. 72, pp. 3072–3079, 1992. View at Publisher · View at Google Scholar
12. D. H. Lee, Y. S. Cho, W. I. Yi, T. S. Kim, J. K. Lee, and H. J. Jung, “Metalorganic chemical vapor deposition of ${\text{TiO}}_{\text{2}}$: N anatase thin film on Si substrate,” Applied physics letters, vol. 66, pp. 815–816, 1995. View at Publisher · View at Google Scholar
13. T. Ihara, M. Miyoshi, Y. Iriyama, O. Matsumoto, and S. Sugihara, “Visible-light-active titanium oxide photocatalyst realized by an oxygen-deficient structure and by nitrogen doping,” Applied Catalysis B: Environmental, vol. 42, no. 4, pp. 403–409, 2003. View at Publisher · View at Google Scholar
14. H. Irie, Y. Watanabe, and K. Hashimoto, “Nitrogen-concentration dependence on photocatalytic activity of ${\text{Tio}}_{2-x}{\text{N}}_x$ powders,” Journal of Physical Chemistry B, vol. 107, no. 23, pp. 5483–5486, 2003. View at Publisher · View at Google Scholar
15. T. Lindgren, J. M. Mwabora, E. Avandaño, et al., “Photoelectrochemical and optical properties of nitrogen doped titanium dioxide films prepared by reactive DC magnetron sputtering,” Journal of Physical Chemistry B, vol. 107, no. 24, pp. 5709–5716, 2003. View at Publisher · View at Google Scholar
16. S. Sakthivel and H. Kisch, “Photocatalytic and photoelectrochemical properties of nitrogen-doped titanium dioxide,” ChemPhysChem, vol. 4, no. 5, pp. 487–490, 2003. View at Publisher · View at Google Scholar · View at PubMed
17. S. Yin, H. Yamaki, M. Komatsu, et al., “Preparation of nitrogen-doped titania with high visible light induced photocatalytic activity by mechanochemical reaction of titania and hexamethylenetetramine,” Journal of Materials Chemistry, vol. 13, no. 12, pp. 2996–3001, 2003. View at Publisher · View at Google Scholar
18. M.-C. Yang, T.-S. Yang, and M.-S. Wong, “Nitrogen-doped titanium oxide films as visible light photocatalyst by vapor deposition,” Thin Solid Films, vol. 469–470, pp. 1–5, 2004. View at Publisher · View at Google Scholar
19. C. Burda, Y. Lou, X. Chen, A. C. S. Samia, J. Stout, and J. L. Gole, “Enhanced nitrogen doping in ${\text{TiO}}_{\text{2}}$ nanoparticles,” Nano Letters, vol. 3, no. 8, pp. 1049–1051, 2003. View at Publisher · View at Google Scholar
20. J. L. Gole, J. D. Stout, C. Burda, Y. Lou, and X. Chen, “Highly efficient formation of visible light tunable ${\text{Tio}}_{2-x}{\text{N}}_x$ photocatalysts and their transformation at the nanoscale,” Journal of Physical Chemistry B, vol. 108, no. 4, pp. 1230–1240, 2004. View at Publisher · View at Google Scholar
21. X. Chen and C. Burda, “Photoelectron spectroscopic investigation of nitrogen-doped titania nanoparticles,” Journal of Physical Chemistry B, vol. 108, no. 40, pp. 15446–15449, 2004. View at Publisher · View at Google Scholar
22. S. M. Prokes, J. L. Gole, X. Chen, C. Burda, and W. E. Carlos, “Defect-related optical behavior in surface-modified ${\text{TiO}}_{\text{2}}$ nanostructures,” Advanced Functional Materials, vol. 15, no. 1, pp. 161–167, 2005. View at Publisher · View at Google Scholar
23. X. Chen, Y. Low, A. C. S. Samia, C. Burda, and J. L. Gole, “Formation of oxynitride as the photocatalytic enhancing site in nitrogen-doped titania nanocatalysts: comparison to a commercial nanopowder,” Advanced Functional Materials, vol. 15, no. 1, pp. 41–49, 2005. View at Publisher · View at Google Scholar
24. C. S. Gopinath, “Comment on “photoelectron spectroscopic investigation of nitrogen-doped titania nanoparticles”,” Journal of Physical Chemistry B, vol. 110, no. 13, pp. 7079–7080, 2006. View at Publisher · View at Google Scholar · View at PubMed
25. S. Sato, R. Nakamura, and S. Abe, “Visible-light sensitization of ${\text{TiO}}_{\text{2}}$ photocatalysts by wet-method N doping,” Applied Catalysis A: General, vol. 284, no. 1-2, pp. 131–137, 2005. View at Publisher · View at Google Scholar
26. E. György, A. Pérez del Pino, P. Serra, and J. L. Morenza, “Depth profiling characterisation of the surface layer obtained by pulsed Nd:YAG laser irradiation of titanium in nitrogen,” Surface and Coatings Technology, vol. 173, no. 2-3, pp. 265–270, 2003. View at Publisher · View at Google Scholar
27. C. Burda and J. Gole, “Reply to comment on photoelectron spectroscopic investigation of nitrogen-doped titania nanoparticles,” Journal of Physical Chemistry B, vol. 110, no. 13, pp. 7081–7082, 2006. View at Publisher · View at Google Scholar
28. H. Irie, Y. Watanabe, and K. Hashimoto, “Nitrogen-concentration dependence on photocatalytic activity of ${\text{TiO}}_{2-x}{\text{N}}_x$ powders,” Journal of Physical Chemistry B, vol. 107, no. 23, pp. 5483–5486, 2003. View at Publisher · View at Google Scholar
29. R. Nakamura, T. Tanaka, and Y. Nakato, “Mechanism for visible light responses in anodic photocurrents at N-doped ${\text{TiO}}_{\text{2}}$ film electrodes,” Journal of Physical Chemistry B, vol. 108, no. 30, pp. 10617–10620, 2004. View at Publisher · View at Google Scholar
30. T. Ma, M. Akiyama, E. Abe, and I. Imai, “High-efficiency dye-sensitized solar cell based on a nitrogen-doped nanostructured titania electrode,” Nano Letters, vol. 5, no. 12, pp. 2543–2547, 2005. View at Publisher · View at Google Scholar · View at PubMed
31. O. Diwald, T. L. Thompson, E. G. Goralski, S. D. Walck, and J. T. Yates, Jr., “The effect of nitrogen ion implantation on the photoactivity of ${\text{TiO}}_{\text{2}}$ rutile single crystals,” Journal of Physical Chemistry B, vol. 108, no. 1, pp. 52–57, 2004. View at Publisher · View at Google Scholar
32. O. Diwald, T. L. Thompson, T. Zubkov, Ed. G. Goralski, S. D. Walck, and J. T. Yates, Jr., “Photochemical activity of nitrogen-doped rutile ${\text{TiO}}_{\text{2}}$(110) in visible light,” Journal of Physical Chemistry B, vol. 108, no. 19, pp. 6004–6008, 2004. View at Publisher · View at Google Scholar
33. T. L. Thompson and J. T. Yates, Jr., “${\text{TiO}}_{\text{2}}$-based photocatalysis: surface defects, oxygen and charge transfer,” Topics in Catalysis, vol. 35, no. 3-4, pp. 197–210, 2005. View at Publisher · View at Google Scholar
34. P. Frach, D. Glöß, M. Vergöhl, F. Neumann, and K. Hund-Rinke, “Photocatalytic properties of titanium dioxide films prepared by reactive pulse magnetron sputtering,” in Proceeding of the 4th International Workshop on the Utilization and Commercialisation of Photocatalytic Systems (EJIPAC '04), Saarbrücken, Germany, October 2004.
35. D. Li, H. Haneda, S. Hishita, and N. Ohashi, “Visible-light-driven nitrogen-doped ${\text{TiO}}_{\text{2}}$ photocatalysts: effect of nitrogen precursors on their photocatalysis for decomposition of gas-phase organic pollutants,” Materials Science and Engineering B: Solid-State Materials for Advanced Technology, vol. 117, no. 1, pp. 67–75, 2005. View at Publisher · View at Google Scholar
36. M. Mrowetz, W. Balcerski, A. J. Colussi, and M. R. Hoffmann, “Oxidative power of nitrogen-doped ${\text{TiO}}_{\text{2}}$ photocatalysts under visible illumination,” Journal of Physical Chemistry B, vol. 108, no. 45, pp. 17269–17273, 2004. View at Publisher · View at Google Scholar
37. Y. Aita, M. Komatsu, S. Yin, and T. Sato, “Phase-compositional control and visible light photocatalytic activity of nitrogen-doped titania via solvothermal process,” Journal of Solid State Chemistry, vol. 177, no. 9, pp. 3235–3238, 2004. View at Publisher · View at Google Scholar
38. R. P. Vitiello, J. M. Macak, A. Ghicov, H. Tsuchiya, L. F. P. Dick, and P. Schmuki, “N-Doping of anodic ${\text{TiO}}_{\text{2}}$ nanotubes using heat treatment in ammonia,” Electrochemistry Communications, vol. 8, no. 4, pp. 544–548, 2006. View at Publisher · View at Google Scholar
39. M. Kitano, K. Funatsu, M. Matsuoka, M. Ueshima, and M. Anpo, “Preparation of nitrogen-substituted ${\text{TiO}}_{\text{2}}$ thin film photocatalysts by the radio frequency magnetron sputtering deposition method and their photocatalytic reactivity under visible light irradiation,” Journal of Physical Chemistry B, vol. 110, no. 50, pp. 25266–25272, 2006. View at Publisher · View at Google Scholar · View at PubMed
40. S.-K. Joung, T. Amemiya, M. Murabayashi, and K. Itoh, “Relation between photocatalytic activity and preparation conditions for nitrogen-doped visible light-driven ${\text{TiO}}_{\text{2}}$ photocatalysts,” Applied Catalysis A: General, vol. 312, no. 1-2, pp. 20–26, 2006. View at Publisher · View at Google Scholar
41. S. In, A. Orlov, F. García, M. Tikhov, D. S. Wright, and R. M. Lambert, “Efficient visible light-active N-doped ${\text{TiO}}_{\text{2}}$ photocatalysts by a reproducible and controllable synthetic route,” Chemical Communications, no. 40, pp. 4236–4238, 2006. View at Publisher · View at Google Scholar · View at PubMed
42. C. Belver, R. Bellod, A. Fuerte, and M. Fernández-García, “Nitrogen-containing ${\text{TiO}}_{\text{2}}$ photocatalysts. Part 1. Synthesis and solid characterization,” Applied Catalysis B: Environmental, vol. 65, no. 3-4, pp. 301–308, 2006. View at Publisher · View at Google Scholar
43. C. Belver, R. Bellod, S. J. Stewart, F. G. Requejo, and M. Fernández-García, “Nitrogen-containing ${\text{TiO}}_{\text{2}}$ photocatalysts. Part 2. Photocatalytic behavior under sunlight excitation,” Applied Catalysis B: Environmental, vol. 65, no. 3-4, pp. 309–314, 2006. View at Publisher · View at Google Scholar
44. T. Matsumoto, N. Iyi, Y. Kaneko, et al., “High visible-light photocatalytic activity of nitrogen-doped titania prepared from layered titania/isostearate nanocomposite,” Catalysis Today, vol. 120, no. 2, pp. 226–232, 2007. View at Publisher · View at Google Scholar
45. T. Tachikawa, M. Fujitsuka, and T. Majima, “Mechanistic insight into the ${\text{TiO}}_{\text{2}}$ photocatalytic reactions: design of new photocatalysts,” Journal of Physical Chemistry C, vol. 111, no. 14, pp. 5259–5275, 2007. View at Publisher · View at Google Scholar
46. R. Asahi, Y. Taga, W. Mannstadt, and A. J. Freeman, “Electronic and optical properties of anatase ${\text{TiO}}_{\text{2}}$,” Physical Review B—Condensed Matter and Materials Physics, vol. 61, no. 11, pp. 7459–7465, 2000.
47. C. Di Valentin, G.-F. Pacchioni, and A. Selloni, “Origin of the different photoactivity of N-doped anatase and rutile ${\text{TiO}}_{\text{2}}$,” Physical Review B—Condensed Matter and Materials Physics, vol. 70, no. 8, Article ID 085116, 2004. View at Publisher · View at Google Scholar
48. C. Di Valentin, G.-F. Pacchioni, A. Selloni, S. Livraghi, and E. Giamello, “Characterization of paramagnetic species in N-doped ${\text{TiO}}_{\text{2}}$ powders by EPR spectroscopy and DFT calculations,” Journal of Physical Chemistry B, vol. 109, no. 23, pp. 11414–11419, 2005. View at Publisher · View at Google Scholar · View at PubMed
49. K. Yang, Y. Dai, H. Baibiao, and H. Shenghao, “Theoretical study of N-doped ${\text{TiO}}_{\text{2}}$ rutile crystals,” Journal of Physical Chemistry B, vol. 110, no. 47, pp. 24011–24014, 2006. View at Publisher · View at Google Scholar · View at PubMed
50. S. Livraghi, M. C. Paganini, E. Giamello, A. Selloni, C. Di Valentin, and G.-F. Pacchioni, “Origin of photoactivity of nitrogen-doped titanium dioxide under visible light,” Journal of the American Chemical Society, vol. 128, no. 49, pp. 15666–15671, 2006. View at Publisher · View at Google Scholar · View at PubMed
51. S. Livraghi, A. Votta, M. C. Paganini, and E. Giamello, “The nature of paramagnetic species in nitrogen doped ${\text{TiO}}_{\text{2}}$ active in visible light photocatalysis,” Chemical Communications, no. 4, pp. 498–500, 2005. View at Publisher · View at Google Scholar · View at PubMed
52. M. A. Henderson, W. S. Epling, C. H. F. Peden, and C. L. Perkins, “Insights into photoexcited electron scavenging processes on ${\text{TiO}}_{\text{2}}$ obtained from studies of the reaction of ${\text{O}}_2$ with OH groups adsorbed at electronic defects on ${\text{TiO}}_{\text{2}}$(110),” Journal of Physical Chemistry B, vol. 107, no. 2, pp. 534–545, 2003. View at Publisher · View at Google Scholar
53. T. Berger, M. Sterrer, O. Diwald, et al., “Light-induced charge separation in anatase ${\text{TiO}}_{\text{2}}$ particles,” Journal of Physical Chemistry B, vol. 109, no. 13, pp. 6061–6068, 2005. View at Publisher · View at Google Scholar · View at PubMed
54. D. C. Hurum, A. G. Agrios, K. A. Gray, T. Rajh, and M. C. Thurnauer, “Explaining the enhanced photocatalytic activity of degussa P25 mixed-phase ${\text{TiO}}_{\text{2}}$ using EPR,” Journal of Physical Chemistry B, vol. 107, no. 19, pp. 4545–4549, 2003. View at Publisher · View at Google Scholar
55. H. Wang and J. P. Lewis, “Second-generation photocatalytic materials: anion-doped ${\text{TiO}}_{\text{2}}$,” Journal of Physics Condensed Matter, vol. 18, no. 2, pp. 421–434, 2006. View at Publisher · View at Google Scholar
56. J. Pascual, J. Camassel, and H. Mathieu, “Fine structure in the intrinsic absorption edge of titanium dioxide,” Physical Review B, vol. 18, pp. 5606–5614, 1978. View at Publisher · View at Google Scholar
57. K. M. Glassford and J. R. Chelikowsky, “Structural and electronic properties of titanium dioxide,” Physical Review B, vol. 46, pp. 1284–1298, 1992. View at Publisher · View at Google Scholar
58. R. Sanjines, H. Tang, H. Berger, F. Gozzo, G. Margaritondo, and F. Levy, “Electronic structure of anatase ${\text{TiO}}_{\text{2}}$ oxide,” Journal of Applied Physics, vol. 75, pp. 2945–2951, 1994. View at Publisher · View at Google Scholar
59. H. Tang, F. Levy, H. Berger, and P. E. Schmid, “Urbach tail of anatase ${\text{TiO}}_{\text{2}}$,” Physical Review B, vol. 52, pp. 7771–7774, 1995. View at Publisher · View at Google Scholar
60. S. D. Mo and W. Y. Ching, “Electronic and optical properties of three phases of titanium dioxide: rutile, anatase, and brookite,” Physical Review B, vol. 51, pp. 13023–13032, 1995. View at Publisher · View at Google Scholar
61. C. Kim, S. J. Doh, S. G. Lee, S. J. Lee, and H. Y. Kim, “Visible-light absorptivity of a zincoxysulfide (${\text{ZnO}}_x{\text{S}}_{1-x}$) composite semiconductor and its photocatalytic activities for degradation of organic pollutants under visible-light irradiation,” Applied Catalysis A: General, vol. 330, no. 1-2, pp. 127–133, 2007. View at Publisher · View at Google Scholar
62. V. N. Kuznetsov and N. Serpone, “Visible light absorption by various titanium dioxide specimens,” Journal of Physical Chemistry B, vol. 110, no. 50, pp. 25203–25209, 2006. View at Publisher · View at Google Scholar · View at PubMed
63. D. Li, N. Ohashi, S. Hishita, T. Kolodiazhnyi, and H. Haneda, “Origin of visible-light-driven photocatalysis: a comparative study on N/F-doped and N-F-codoped ${\text{TiO}}_{\text{2}}$ powders by means of experimental characterizations and theoretical calculations,” Journal of Solid State Chemistry, vol. 178, no. 11, pp. 3293–3302, 2005. View at Publisher · View at Google Scholar
64. J. Wang, W. Zhu, Y. Zhang, and S. Liu, “An efficient two-step technique for nitrogendoped titanium dioxide synthesizing: visible-light-induced photodecomposition of methylene blue,” The Journal of Physical Chemistry C, vol. 111, pp. 1010–1014, 2007. View at Publisher · View at Google Scholar
65. T. Sekiya, K. Ichimura, M. Igarashi, and S. Kurita, “Absorption spectra of anatase ${\text{TiO}}_{\text{2}}$ single crystals heat-treated under oxygen atmosphere,” Journal of Physics and Chemistry of Solids, vol. 61, no. 8, pp. 1237–1242, 2000. View at Publisher · View at Google Scholar
66. T. Sekiya, T. Yagisawa, N. Kamiya, et al., “Defects in anatase ${\text{TiO}}_{\text{2}}$ single crystal controlled by heat treatments,” Journal of the Physical Society of Japan, vol. 73, no. 3, pp. 703–710, 2004. View at Publisher · View at Google Scholar
67. N. Serpone, “Is the band gap of pristine ${\text{TiO}}_{\text{2}}$ narrowed by anion- and cation-doping of titanium dioxide in second-generation photocatalysts?,” Journal of Physical Chemistry B, vol. 110, no. 48, pp. 24287–24293, 2006. View at Publisher · View at Google Scholar · View at PubMed
68. J. Chen, L.-B. Lin, and F.-Q. Jing, “Theoretical study of F-type color center in rutile ${\text{TiO}}_{\text{2}}$,” Journal of Physics and Chemistry of Solids, vol. 62, no. 7, pp. 1257–1262, 2001. View at Publisher · View at Google Scholar
69. K. Suriye, P. Praserthdam, and B. Jongsomjit, “Control of ${\text{Ti}}^{3+}$ surface defect on ${\text{TiO}}_{\text{2}}$ nanocrystal using various calcination atmospheres as the first step for surface defect creation and its application in photocatalysis,” Applied Surface Science, vol. 253, no. 8, pp. 3849–3855, 2007. View at Publisher · View at Google Scholar
70. V. N. Kuznetsov and N. Serpone, “Photo-induced coloration and photobleaching of titanium dioxide in ${\text{TiO}}_{\text{2}}$/polymer compositions on UV- and visible-light excitation into the color centers' absorption bands. Direct experimental evidence negating band gap narrowing in anion-/cation-doped ${\text{TiO}}_{\text{2}}$,” The Journal of Physical Chemistry C, vol. 111, pp. 15277–15288, 2007. View at Publisher · View at Google Scholar
71. A. V. Emeline, N. V. Sheremetyeva, N. V. Khomchenko, V. K. Ryabchuk, and N. Serpone, “Photoinduced formation of defects and nitrogen stabilization of color centers in N-doped titanium dioxide,” Journal of Physical Chemistry C, vol. 111, no. 30, pp. 11456–11462, 2007. View at Publisher · View at Google Scholar