1 research outputs found
Shedding Light on Aging of N‑Doped Titania Photocatalysts
A detailed analysis of nitrogen dopant
behavior in nanostructured
microspheres of the TiO<sub>2</sub> photocatalyst obtained by the
thermally assisted reactions in aqueous sprays method has been performed
for the first time using electron paramagnetic resonance, X-ray photoelectron
spectroscopy, and UV–vis spectroscopy and is supported by theoretical
simulation of possible defect structures. The nitrogen species were
found to undergo the N<sup>•</sup> to N<sup>–</sup> transformation
during sample storage under different conditions, with an activation
energy of about 0.45 eV. Three main possible evolution pathways for
the dopant state were identified and discussed. It was established
that the most probable transformation consists of migration of an
oxygen vacancy site to an interstitial nitrogen atom followed by the
formation of a nonparamagnetic substitution nitrogen center. Possible
diffusion routes of oxygen vacancy and corresponding energy barriers
were estimated and found to be in agreement with experimental observations