About the Nitrogen Location in Nanocrystalline N-Doped TiO₂: Combined DFT and EXAFS Approach

Abstract

N-doped titanium dioxide is one of the most promising materials for photocatalysis in the visible region. The exact location of nitrogen in the host lattice is still under debate. Here, we synthesized a series of N-doped titania nanoparticles. Average Ti nearest neighbors distances were obtained from EXAFS experiments and compared with DFT calculations at different levels of theory. The comparison shows that N substitutes oxygen at low levels of doping, whereas oxygen vacancy creation is observed at higher dopant concentrations. Overall, this article illustrates a general method for bulk characterization based on DFT and EXAFS approaches, which can be extended to several systems.

Influence of electronic structure on visible light photocatalytic activity of nitrogen-doped TiO2

“…Therefore, the reduction of TiO 2 takes place at 550 C. This onset temperature is consistent with the decomposition temperature of NH 3 and therefore, the reduction and subsequent N incorporation are indeed caused by atomic H generated by decomposition of NH 3 36. The present results are supported by theoretical prediction showing that the introduction of V O stabilizes the formation of N s [37][38][39].…”

Unraveling the Cooperative Mechanism of Visible-Light Absorption in Bulk N,Nb Codoped TiO2 Powders of Nanomaterials

“…The Horae suite of programs 41 , based on the IFEFFIT library 42 , was used throughout data processing and fitting. The same multi-step fitting strategy described in detail elsewhere 43 was applied to extract information on the average coordination geometry around Ti. As for the spectra at the Nb K-edge, we considered as negligible the amount of dopant possibly present in the minority phase of brookite with respect to the major anatase one.…”

Consequences of Nitrogen Doping and Oxygen Enrichment on Titanium Local Order and Photocatalytic Performance of TiO2 Anatase

“…They discovered that the N-doping was responsible for the oxygen-vacancies formation in titanium dioxide. In a more recent investigation supported by DFT calculations and EXAFS, Ceotto et al postulated that nitrogen preferentially occupies the axial position in the TiO 6 polyhedra replacing the lattice oxygen at low doping levels and forming oxygen-vacancies at high dopant concentrations 31 . Several years later, Sahoo et al found out by means of EXAFS that the nitrogen interstitial doping is responsible for the reduction of Ti-O coordination number and the increase of the axial and equatorial Ti-O bond lengths 32 .…”