Magnetic resonance study of annealed and rinsed N-doped TiO2 nanoparticles

作者：Guskos Niko^*; Typek Janusz; Guskos Aleksander; Zolnierkiewicz Grzegorz; Berczynski Pawel; Dolat Diana; Grzmil Barbara; Morawski Antoni

来源：Central European Journal of Chemistry, 2013, 11(12): 1996-2004.

DOI：10.2478/s11532-013-0340-2

• Photocatalytic activity
• Electron paramagnetic resonance

Nanoparticles of nitrogen-modified TiO2 (N-doped TiO2) calcined at 300A degrees C and 350A degrees C, have been prepared with and without water rinsing. Samples were characterized by x-ray diffractrometry (XRD) and optical spectroscopy. The electron paramagnetic resonance (EPR) spectra from centers involving oxygen vacancies were recorded for all samples. These could be attributed to paramagnetic surface centers of the hole type, for example to paramagnetic oxygen radicals O-, O-2 (-) etc. The concentration of these centers increased after water rising and it further increased for samples annealed at higher temperature. Additionally, for samples calcined at 300A degrees C, and calcined at 350A degrees C and rinsed, the EPR spectra evidenced the presence of magnetic clusters of Ti3+ ions. The photocatalytic activity of samples was studied towards phenol decomposition under unltraviolet-visible (UV-Vis) irradiation. It was found that, in comparison to the starting materials, the rinsed materials showed increased photocatalytic activity towards phenol oxidation. The light absorption (UV-Vis/DRS) as well as surface Fourier transform infrared/diffuse reflectance spectroscopy (FTIR/DR) studies confirmed a significantly enhanced light absorption and the presence of nitrogen groups on the photocatalysts surfaces, respectively. A significant increase of concentration of paramagnetic centers connected with oxygen vacancies after water rising has had an essential influence on increasing their photocatalytic activity.

• 出版日期2013-12