Peculiarities of sol-gel synthesis of co-modified by nitrogen and metal ions (Zn2+, Zr4+, Pt2+) semiconductive TiO2 films

Linnik, ОP
Smirnova, NP
Eremenko, AМ
Dopov. Nac. akad. nauk Ukr. 2020, 12:67-74
Section: Chemistry
Language: Ukrainian

According to the XPS investigation of titania films co-modified by nitro gen and metal ions obtained via sol-gel method, the formation of common bonds between elements occurs due to the presence of metal ions. The mechanism of urea thermolysis is changed as a result of the ability of metal ions to form the complex compounds with urea molecules under the reported synthesis conditions that, in turn, depends on the nature of metal ions, leading to the different chemical compositions of materials’ surface. The XPS data show that nitrogen atoms are surrounded by nonmetal ones on the surface of the films modi fied by Zn2+ or Zr4+ ions. It is suggested that no formation of the complexes between Ті, Zn, or Zr atoms with urea occurs due to its protonation through an oxygen atom leading to the formation of O,N-containing reaction products. In the case of Pt2+ doping, the substitutional nitrogen incorporation in the titania lattice, as well as the formation of N-containing fragments, have been detected. The chemical nature of Pt ions allows them to interact with urea molecules through an N atom of the amino group. As a result, the transformation of urea molecules in the complexes occurs at higher temperatures concurrently with the titania crystallization that is recognized as a catalyst for the intermediates of the urea decomposition leading to the formation of common bonds between N and Ti atoms.

Keywords: metal ions, sol-gel synthesis, titania, urea, XPS

1. Wu, C.-H., Kuo, C.-Y., Lin, C.-J. & Chiu, P.-K. (2013). Preparation of N–TiO2 using a microwave/sol-gel method and its photocatalytic activity for bisphenol A under visible-light and sunlight irradiation. Int. J. Photoenergy, 439079, pp. 1-9.
2. Sakatani, Y., Ando, H., Okusako, K., Koike, H., Nunoshige, J., Takata, T., Kondo, J. N., Hara, M. & Domen, K. (2004). Metal ion and N co-doped TiO2 as a visible-light photocatalyst. J. Mater. Res., 19, pp. 2100-2108.
3. Mitoraj, D. & Kisch, H. (2008). The nature of nitrogen-modified titanium dioxide photocatalysts active in visible light. Angew. Chemie Int. Ed., 47, pp. 9975-9978.
4. Schmidt, D. T. A. (1966). Herstellung von melamin aus harnstoff bei atmosphärendruck. Chem. Ing. Tech., 38, pp. 1140-1144.
5. Theophanides, T. & Harvey, P. D. (1987). Structural and spectroscopic of metal-urea complexes. Coord. Chem. Rev., 76, pp. 237–264.
6. Woon, T. C., Wickramasinghe, W. A. & Fairlie, D. P. (1993). Oxygen versus nitrogen coordination of a urea to (diethylenetriamine)platinum(II). Inorg. Chem., 32, pp. 2190-2194.
7. Shestopal, N. A., Linnik, O. P. & Smirnova, N. P. (2015). Influence of metal and non-metal ions doping on the structural and photocatalytic properties of titania films. Chem. Phys. Technol. Surf., 6, pp. 203-210.
8. Yan, X., Xu, T., Chen, G., Yang, S., Liu, H. & Xue, Q. (2004). Preparation and characterization of electrochemically deposited carbon nitride films on silicon substrate. J. Phys. D. Appl. Phys., 37, pp. 1-7.
9. City, I. (1964). The pH of urea solutions. Arch. Biochem. Biophys., 104, pp. 297-304.
10. Brinker, C. J. & Scherer, G. W. (1990). Sol-gel science: the physics and chemistry of sol-gel processing. Boston: Academic Press.
11. Linnik, O., Chorna, N. & Smirnova, N. (2017). Nonporous iron titanate thin films doped with nitrogen: optical, structural and photocatalytic properties. Nanoscale Res. Lett., 12, pp. 249-258.
12. Chorna, N., Smirnova, N., Vorobets, V., Kolbasov, G. & Linnik, O. (2019). Nitrogen doped iron titanate films: photoelectrochemical, electrocatalytic, photocatalytic and structural features. Appl. Surf. Sci., 473, pp. 343-351.
13. Schaber, P. M., Colson, J., Higgins, S., Thielen, D., Anspach, B. & Brauer, J. (2004). Thermal decomposition (pyrolysis ) of urea in an open reaction vessel. Thermochim. Acta, 424, pp. 131-142.
14. Ihnatiuk, D., Tossi, C., Tittonen, I. & Linnik, O. (2020). Effect of synthesis conditions of nitrogen and platinum co-doped titania films on the photocatalytic performance under simulated solar light. Catalysts, 10, 1074.
15. Qiu Y. & Gao, L. (2004). Metal-urea complex — a precursor to metal nitrides. J. Am. Ceram. Soc., 87, pp. 352-357.